chemistry level) (cie) paper 2

This question paper consists of 11 printed pages and 1 blank page.

SP (SM/JB) S07970/4© CIE 2002 [Turn over

CAMBRIDGE INTERNATIONAL EXAMINATIONS

General Certificate of EducationAdvanced Subsidiary Level and Advanced Level

CHEMISTRY 9701/2PAPER 2

MAY/JUNE SESSION 20021 hour

Candidates answer on the question paper.Additional materials:

Data Booklet

TIME 1 hour

INSTRUCTIONS TO CANDIDATES

Write your name, Centre number and candidate number in the spaces at the top of this page.

Answer all questions.

Write your answers in the spaces provided on the question paper.

INFORMATION FOR CANDIDATES

The number of marks is given in brackets [ ] at the end of each question or part question.

You may lose marks if you do not show your working or if you do not use appropriate units.

A Data Booklet is provided.

CandidateCentre Number Number

Candidate Name

UNIVERSITY of CAMBRIDGELocal Examinations Syndicate

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1 Sir James Jeans, who was a great populariser of science, once described an atom of carbonas being like six bees buzzing around a space the size of a football stadium.

(a) (i) Suggest what were represented by the six bees in this description.

...................................................................................................................................

(ii) Explain (in terms of an atom of carbon) what stopped the bees from flying awayfrom the space of the football stadium.

...................................................................................................................................

...................................................................................................................................

(iii) What is missing from Jeans’ description when applied to an atom of carbon?

...................................................................................................................................

...................................................................................................................................[3]

(b) The diagram below represents the energy levels of the orbitals in atoms of the secondperiod, lithium to neon.

(i) Label the energy levels to indicate the principal quantum number and the type oforbital at each energy level.

(ii) In the space below, sketch the shapes of the two types of orbital.

ener

gy

nucleus

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(iii) Complete the electron configurations of nitrogen and oxygen on the energy leveldiagrams below, using arrows to represent electrons.

(iv) Explain, with reference to your answer to (iii), the relative values of the firstionisation energies of nitrogen and oxygen. The values are given in the DataBooklet and should be quoted in your answer.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[6]

(c) (i) State the formulae of the negatively charged ions formed by these elements insimple binary compounds (nitrides and oxides).

...................................................................................................................................

(ii) Why do nitrogen and oxygen form negative ions, but not positive ions, in simplebinary compounds?

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[2]

[Total : 11]

nitrogen oxygen

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2 Ethanol, C2H5OH, is a most important industrial chemical and is used as a solvent, a fueland an intermediate in large scale organic synthesis.

Ethanol is prepared industrially by the reaction of ethene and steam in the presence of acatalyst.

C2H4(g) + H2O(g) → C2H5OH(g)

The standard enthalpy change of the reaction can be determined by using the standardenthalpy changes of combustion, ∆Hc, at 298 K.

∆Hc / kJ mol–1

C2H4(g) –1411

C2H5OH(l) –1367

(a) Calculate the standard enthalpy change for the following reaction.

C2H4(g) + H2O(l) → C2H5OH(l)

[2]

(b) (i) Define the term standard enthalpy change of combustion.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) Explain why the state symbols for water and ethanol given in the equation in (a)have been changed from those quoted in the industrial process.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(iii) Write the equation for the complete combustion of ethanol.

...................................................................................................................................[4]

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�

�

5


(c) Ethanol is miscible with water because of hydrogen bonding between molecules ofethanol and water. Draw a diagram, including dipoles, to show the hydrogen bondingbetween a molecule of ethanol and a molecule of water.

[2]

[Total : 8]

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3 Aluminium is the third most abundant element in the Earth’s crust, occurring combined inmany minerals.

(a) Name a mineral from which aluminium may be extracted.

......................................................................................................................................[1]

(b) (i) Describe with the aid of a diagram, the electrolytic extraction of aluminium frompurified aluminium oxide. State what the electrodes are made of.

(ii) Give an ion-electron equation for the electrode process

at the cathode, .........................................................................................................

at the anode. ............................................................................................................

(iii) What further reaction takes place at the anode?

...................................................................................................................................

...................................................................................................................................[8]

(c) Much of the bodywork of trains, aircraft and ships is made from aluminium rather thanfrom steel. State two advantages of using aluminium in the making of vehicles.

1. .....................................................................................................................................

..........................................................................................................................................

2. .....................................................................................................................................

......................................................................................................................................[2]

[Total : 11]

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4 Sulphuric acid is used in many industrial processes of major importance.

The first stage in the manufacture of sulphuric acid is to pass air over burning sulphur.The emerging gas has the following composition by volume.

sulphur dioxide 10%sulphur trioxide 0.2%oxygen 10%nitrogen etc. 79–80%

(a) (i) Write an equation for sulphur burning in air.

...................................................................................................................................

(ii) Suggest why the air is passed so fast that only half the oxygen is used.

...................................................................................................................................

...................................................................................................................................[2]

The emerging gas is passed over a catalyst maintained at 450–550 °C in the reactionchamber.

(b) Name the catalyst used in the Contact process.

......................................................................................................................................[1]

Sulphur trioxide is formed in 98% yield; 2% of sulphur dioxide remains unconverted.

2SO2(g) + O2(g) 2SO3(g) ∆H = –197 kJ mol–1

(c) The high yield is only achieved under certain conditions.

After each condition explain why this leads to an increased yield of sulphur trioxide.

(i) There needs to be an excess of air in the reacting gas mixture.

explanation ..............................................................................................................

...................................................................................................................................

(ii) The catalyst needs to be cooled.

explanation ..............................................................................................................

...................................................................................................................................

(iii) The air used to burn the sulphur must be as clean as possible.

explanation .............................................................................................................

...................................................................................................................................[3]

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(d) In modern plants, nearly all the SO2/SO3 mixture is absorbed but up to 0.05% byvolume of SO2 may be allowed to pass into the atmosphere through a chimney stack.

Give two reasons why SO2 should not be discharged into the atmosphere.

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

(e) (i) When concentrated sulphuric acid is warmed with solid sodium chloride, mistyfumes are produced.

Identify the fumes. ...................................................................................................

Write an equation for the reaction.

...................................................................................................................................

(ii) When concentrated sulphuric acid is warmed with solid sodium iodide, purplefumes are produced.

Identify the fumes. ...................................................................................................[3]

[Total : 11]

5 Crude oil is the principal source of hydrocarbons. The following are examples of suchhydrocarbons.

(a) Give the structural formulae of the organic products in the following reactions.

(i) The reaction of ethane with bromine in the presence of u.v. light.

(ii) The polymerisation of propene.

H

H H

H H

C C H C C

H

H

H

CH3

ethane propene cyclohexene

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(iii) The oxidation of propene with cold, acidified potassium manganate(VII).

(iv) The reaction of cyclohexene with hydrogen bromide.

(v) The reaction of cyclohexene with hot acidified potassium manganate(VII).

[5]

(b) Write equations for the following reactions.

(i) The complete combustion of ethane.

(ii) The action of steam on propene in the presence of a catalyst.

(iii) The reaction of cyclohexene with hydrogen in the presence of a catalyst.

[3]

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(c) The process of cracking produces useful substances from oil.

(i) Explain why cracking is useful.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) Suggest an equation for the cracking of C16H34 into at least three fragments.

[3]

[Total : 11]

6 Chlorofluorocarbons, CFCs, are small alkane molecules in which some of the hydrogenatoms have been replaced by atoms of chlorine and fluorine.

(a) (i) State two uses of CFCs.

...................................................................................................................................

...................................................................................................................................

(ii) What property of CFCs causes them to be useful?

...................................................................................................................................[2]

(b) A typical CFC is CHF2CHClF.

(i) Which covalent bond in this CFC is the weakest?

...................................................................................................................................

(ii) Why does this CFC present an environmental concern?

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[3]

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(c) Another CFC contains the following elements by mass. The value of its M r is 135.

C, 17.8%; H, 1.5%; Cl , 52.6%; F, 28.1%

Use these data to determine the molecular formula of the CFC.

[3]

[Total : 8]

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This document consists of 9 printed pages and 3 blank pages.

SP (AT) S30314/3© CIE 2003 [Turn over

CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education

Advanced Subsidiary Level and Advanced Level

CHEMISTRY 9701/02

Paper 2 Structured Questions AS CoreMay/June 2003

1 hourCandidates answer on the Question Paper.Data Booklet.

READ THESE INSTRUCTIONS FIRST

Write your name, Centre number and candidate number in the spaces at the top of this page.Write in dark blue or black pen in the spaces provided on the Question Paper.You may use a pencil for any diagrams, graphs, or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.

Answer all questions.The number of marks is given in brackets [ ] at the end of each question or part question.You may lose marks if you do not show your working or if you do not use appropriate units.A Data Booklet is provided.

Centre Number Candidate Number Name

If you have been given a label, look at thedetails. If any details are incorrect ormissing, please fill in your correct detailsin the space given at the top of this page.

Stick your personal label here, ifprovided.

For Examiner’s Use

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1 (a) Define an isotope in terms of its sub-atomic particles.

..........................................................................................................................................

..........................................................................................................................................[1]

(b) In a mass spectrometer some hydrogen chloride molecules will split into atoms. Themass spectrum of HCl is given. Chlorine has two isotopes. The hydrogen involved hereis the isotope 11H only.

(i) What particle is responsible for the peak at mass 35? .............................................

(ii) What particle is responsible for the peak at mass 38? .............................................[2]

(c) Use the relative heights of the peaks to determine the proportions of the two isotopes ofchlorine. Explain simply how you obtained your answer.

[2]

(d) Use your answer to (c) to explain why chlorine has a relative atomic mass of 35.5.

[1]

[Total : 6]

035 40

20

40

60

80

100

relativeabundance

m /e

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2 This question is about the physical chemistry of gases, with particular emphasis on the inertgas argon. Argon exists in the atmosphere as single atoms.

(a) State two of the assumptions of the kinetic theory as applied to an inert gas.

(i) ...................................................................................................................................

...................................................................................................................................

(ii) .....................................................................................................................................

......................................................................................................................................[2]

(b) How many atoms of argon are present in one mole of the gas?

......................................................................................................................................[1]

(c) You are to calculate the percentage of the volume occupied by the atoms themselves inone mole of argon at room temperature and pressure.

(i) Use the Data Booklet to calculate the volume of one atom of argon.[volume = �₃πr 3 π = 3.14]

(ii) Use your answer to (c)(i) to calculate the volume of one mole of argon atoms.

(iii) State the volume occupied by one mole of argon (assume it to behave as an idealgas) at room temperature and pressure.

...................................................................................................................................

(iv) What percentage of this volume is occupied by the atoms themselves?

(v) Explain how your answer to (c)(iv) justifies one of your assumptions in (a).

...................................................................................................................................

...................................................................................................................................[5]

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(d) Argon is used to fill electric light bulbs. These have a fine filament of a metal wire,usually tungsten, which glows white hot from its electrical resistance to the current.

Suggest why argon, rather than air, is used to fill electric light bulbs.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

[Total : 10]

3 In the Haber Process, ammonia is synthesised from its elements.

(a) Write an equation for the Haber process and state whether it is endo- or exo-thermic.

......................................................................................................................................[2]

(b) What are the three usual operating conditions of the Haber Process?

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

(c) Explain the considerations which lead to the temperature you have stated in (b) beingused.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

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(d) Under certain conditions the equilibrium pressures of the three gases are

nitrogen 44.8 atm,hydrogen 105.6 atm,ammonia 37.2 atm.

(i) Write an expression for the equilibrium constant, Kp, for the Haber Process.

(ii) Calculate Kp from these data, giving the units.

[4]

(e) One of the uses of ammonia is to form nitrates which are used as efficient inorganicfertilisers. The uncontrolled use of these fertilisers has led to environmental problems.Briefly describe and explain these problems.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

[Total : 13]

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4 (a) The use of the Data Booklet is relevant to this question. Complete these sketches forelements of the third period (sodium to argon) to show how each property changesalong the period.

[6]

(b) (i) In the boxes below, write the formulae of one of the oxides of each of these fiveelements.

(ii) Write an equation for sodium oxide reacting with water.

...................................................................................................................................

(iii) Write an equation for your chosen oxide of sulphur reacting with an alkali.

...............................................................................................................................[3]

[Total : 9]

Na

meltingpoint

Mg Al Si P S Cl Ar

(i)

Na

electricalconductivity

Mg Al Si P S Cl Ar

(ii)

Na

atomicradius

Mg Al Si P S Cl Ar

(iii)

Na

ionicradius

Mg Al Si P S Cl Ar

(iv)

ForExaminer’s

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sodium magnesium aluminium phosphorus sulphur



7


5 (a) Draw a section of poly(propene), showing three repeat units.

[1]

(b) To what homologous series does poly(propene) belong?

......................................................................................................................................[1]

(c) When a rupture (hernia) or a deep wound, e.g. as a result of a sports accident, isrepaired by surgery, a mesh is inserted below the muscle tissue so that on healing thewound is less likely to reopen and the repair is stronger.

Poly(propene) is the recommended material for the mesh.

(i) Suggest two reasons why poly(propene) is used rather than a natural fibre such ascotton.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) Members of the homologous series you have given in (b) are considered to havetwo different kinds of reactions. Explain why neither of them can take place in apoly(propene) mesh inserted in living body tissues.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...............................................................................................................................[4]

[Total : 6]

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6 A compound, A, has the following composition by mass.

C, 66.7%; H, 11.1%; O, 22.2%.

It has an Mr of 72.

(a) Calculate the molecular formula of A.

[2]

(b) A reacts with 2,4-dinitrophenylhydrazine but not with Fehling’s or Tollens’ reagents.

(i) State what you would see when A reacts with the 2,4-dinitrophenylhydrazinereagent.

...................................................................................................................................

(ii) State what functional group is present in A. .............................................................

(iii) Identify A either by name or by its structural formula.

...............................................................................................................................[3]

(c) A can be reduced to compound B.

For this reaction

(i) state a suitable reducing agent, ................................................................................

(ii) name the functional group in B (two words are required),

...................................................................................................................................

(iii) give the structural formula of B.

[3]

[Total : 8]

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7 (a) (i) This question is about esters; esters occur naturally and are widely used.In the boxes below, draw the structural formulae of any three different esters thathave the molecular formula C5H10O2.

(ii) Write an equation for the hydrolysis of one of these esters by hot, aqueous sodiumhydroxide.

...............................................................................................................................[4]

(b) State two general physical properties of esters.

(i) ...................................................................................................................................

(ii) ...............................................................................................................................[2]

(c) State two commercial uses of esters.

(i) ...................................................................................................................................

(ii) ...............................................................................................................................[2]

[Total : 8]

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SP (AT) S30314/3© CIE 2003 [Turn over



CHEMISTRY 9701/02


1 hourCandidates answer on the Question Paper.Data Booklet.








1

2

3

4

5

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7

TOTAL


2

9701/2/M/J/03

1 (a) Define an isotope in terms of its sub-atomic particles.

..........................................................................................................................................

..........................................................................................................................................[1]

(b) In a mass spectrometer some hydrogen chloride molecules will split into atoms. Themass spectrum of HCl is given. Chlorine has two isotopes. The hydrogen involved hereis the isotope 11H only.

(i) What particle is responsible for the peak at mass 35? .............................................

(ii) What particle is responsible for the peak at mass 38? .............................................[2]

(c) Use the relative heights of the peaks to determine the proportions of the two isotopes ofchlorine. Explain simply how you obtained your answer.

[2]

(d) Use your answer to (c) to explain why chlorine has a relative atomic mass of 35.5.

[1]

[Total : 6]

035 40

20

40

60

80

100

relativeabundance

m /e

ForExaminer’s

Use

3


2 This question is about the physical chemistry of gases, with particular emphasis on the inertgas argon. Argon exists in the atmosphere as single atoms.

(a) State two of the assumptions of the kinetic theory as applied to an inert gas.

(i) ...................................................................................................................................

...................................................................................................................................

(ii) .....................................................................................................................................

......................................................................................................................................[2]

(b) How many atoms of argon are present in one mole of the gas?

......................................................................................................................................[1]

(c) You are to calculate the percentage of the volume occupied by the atoms themselves inone mole of argon at room temperature and pressure.

(i) Use the Data Booklet to calculate the volume of one atom of argon.[volume = �₃πr 3 π = 3.14]

(ii) Use your answer to (c)(i) to calculate the volume of one mole of argon atoms.

(iii) State the volume occupied by one mole of argon (assume it to behave as an idealgas) at room temperature and pressure.

...................................................................................................................................

(iv) What percentage of this volume is occupied by the atoms themselves?

(v) Explain how your answer to (c)(iv) justifies one of your assumptions in (a).

...................................................................................................................................

...................................................................................................................................[5]

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(d) Argon is used to fill electric light bulbs. These have a fine filament of a metal wire,usually tungsten, which glows white hot from its electrical resistance to the current.

Suggest why argon, rather than air, is used to fill electric light bulbs.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

[Total : 10]

3 In the Haber Process, ammonia is synthesised from its elements.

(a) Write an equation for the Haber process and state whether it is endo- or exo-thermic.

......................................................................................................................................[2]

(b) What are the three usual operating conditions of the Haber Process?

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

(c) Explain the considerations which lead to the temperature you have stated in (b) beingused.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

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5


(d) Under certain conditions the equilibrium pressures of the three gases are

nitrogen 44.8 atm,hydrogen 105.6 atm,ammonia 37.2 atm.

(i) Write an expression for the equilibrium constant, Kp, for the Haber Process.

(ii) Calculate Kp from these data, giving the units.

[4]

(e) One of the uses of ammonia is to form nitrates which are used as efficient inorganicfertilisers. The uncontrolled use of these fertilisers has led to environmental problems.Briefly describe and explain these problems.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

[Total : 13]

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4 (a) The use of the Data Booklet is relevant to this question. Complete these sketches forelements of the third period (sodium to argon) to show how each property changesalong the period.

[6]

(b) (i) In the boxes below, write the formulae of one of the oxides of each of these fiveelements.

(ii) Write an equation for sodium oxide reacting with water.

...................................................................................................................................

(iii) Write an equation for your chosen oxide of sulphur reacting with an alkali.

...............................................................................................................................[3]

[Total : 9]

Na

meltingpoint

Mg Al Si P S Cl Ar

(i)

Na

electricalconductivity

Mg Al Si P S Cl Ar

(ii)

Na

atomicradius

Mg Al Si P S Cl Ar

(iii)

Na

ionicradius

Mg Al Si P S Cl Ar

(iv)

ForExaminer’s

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sodium magnesium aluminium phosphorus sulphur

7


5 (a) Draw a section of poly(propene), showing three repeat units.

[1]

(b) To what homologous series does poly(propene) belong?

......................................................................................................................................[1]

(c) When a rupture (hernia) or a deep wound, e.g. as a result of a sports accident, isrepaired by surgery, a mesh is inserted below the muscle tissue so that on healing thewound is less likely to reopen and the repair is stronger.

Poly(propene) is the recommended material for the mesh.

(i) Suggest two reasons why poly(propene) is used rather than a natural fibre such ascotton.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) Members of the homologous series you have given in (b) are considered to havetwo different kinds of reactions. Explain why neither of them can take place in apoly(propene) mesh inserted in living body tissues.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...............................................................................................................................[4]

[Total : 6]

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6 A compound, A, has the following composition by mass.

C, 66.7%; H, 11.1%; O, 22.2%.

It has an Mr of 72.

(a) Calculate the molecular formula of A.

[2]

(b) A reacts with 2,4-dinitrophenylhydrazine but not with Fehling’s or Tollens’ reagents.

(i) State what you would see when A reacts with the 2,4-dinitrophenylhydrazinereagent.

...................................................................................................................................

(ii) State what functional group is present in A. .............................................................

(iii) Identify A either by name or by its structural formula.

...............................................................................................................................[3]

(c) A can be reduced to compound B.

For this reaction

(i) state a suitable reducing agent, ................................................................................

(ii) name the functional group in B (two words are required),

...................................................................................................................................

(iii) give the structural formula of B.

[3]

[Total : 8]

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7 (a) (i) This question is about esters; esters occur naturally and are widely used.In the boxes below, draw the structural formulae of any three different esters thathave the molecular formula C5H10O2.

(ii) Write an equation for the hydrolysis of one of these esters by hot, aqueous sodiumhydroxide.

...............................................................................................................................[4]

(b) State two general physical properties of esters.

(i) ...................................................................................................................................

(ii) ...............................................................................................................................[2]

(c) State two commercial uses of esters.

(i) ...................................................................................................................................

(ii) ...............................................................................................................................[2]

[Total : 8]

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This document consists of 7 printed pages and 1 blank page.

SP (SC) S52970/3© UCLES 2004 [Turn over

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education


CHEMISTRY 9701/02


1 hour 15 minutesCandidates answer on the Question Paper.Data Booklet.








1

2

3

4

5

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2

9701/02/M/J/04

1 (a) State two assumptions of ideal gas behaviour.

(i) ...................................................................................................................................

...................................................................................................................................

(ii) ...................................................................................................................................

...............................................................................................................................[2]

Use of the Data Booklet is relevant in (b) and (c).

(b) The ideal gas equation is pV = nRT. Explain as fully as you can the meaning of thefollowing terms, and give the units for each to correspond with the value of R given inthe Data Booklet.

(i) p ................................................................................................................................

...................................................................................................................................

(ii) V ...............................................................................................................................

...................................................................................................................................

(iii) T ................................................................................................................................

...............................................................................................................................[6]

(c) (i) When an evacuated glass bulb of volume 63.8 cm3 is filled with a gas at 24 °C and99.5 kPa, the mass increases by 0.103 g. Deduce whether the gas is ammonia,nitrogen or argon.

(ii) Explain why ammonia is the most likely of these three gases to deviate from idealgas behaviour.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...............................................................................................................................[5]

[Total : 13]

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© UCLES 2004



© UCLES 2004

3


2 Compounds of phosphorus have many uses in everyday life, e.g. fertilisers, matches and in watersofteners.

(a) State the full electronic configuration of phosphorus.

...............................................................................................................................................[1]

(b) Phosphoric acid, H3PO4, is used in the manufacture of phosphate fertilisers.

Deduce the oxidation number of phosphorus in H3PO4.

...............................................................................................................................................[1]

(c) The salt sodium phosphate, Na3PO4, is a water-softening agent.

(i) Write the equation for the complete neutralisation of phosphoric acid with aqueoussodium hydroxide.

............................................................................................................................................

Sodium phosphate was prepared from 50.0 cm3 of 0.500 mol dm–3 H3PO4 and an excess ofaqueous sodium hydroxide.

(ii) How many moles of H3PO4 were used?

(iii) Use your equation in (c)(i) to calculate how many moles of sodium hydroxide arerequired.

[3]

(d) Phosphorus sulphide, P4S3, is used in small amounts in the tip of a match. On striking amatch, this compound burns.

(i) Construct an equation for this reaction.

............................................................................................................................................

(ii) Both oxides formed in (i) dissolve in water to give acidic solutions. Construct an equationfor the reaction of each oxide with water.

............................................................................................................................................

........................................................................................................................................[4]

[Total : 9]



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3 Ammonia, NH3, is a colourless, pungent-smelling gas which has been known to man fromthe beginning of recorded time. It is given off from urine such as that on a wet nappy from ababy.

The nitrogen-containing substance in urine is urea, CO(NH2)2, and this decomposes byhydrolysis into ammonia and another colourless gas.

(a) Construct an equation for the hydrolysis of aqueous urea.

......................................................................................................................................[2]

Ammonia was named after the shrine of Jupiter Ammon which was near the Egyptian-Libyan border. In ancient times ammonia was obtained by distilling camel dung.

(b) Now ammonia is synthesised from its elements in the Haber Process.

(i) Write an equation for this process.

...................................................................................................................................

(ii) State the three usual operating conditions of the Haber Process.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(iii) State two modern commercial uses of ammonia.

...................................................................................................................................

...............................................................................................................................[4]

(c) 1.20 dm3 of ammonia gas were dissolved in water to form 200 cm3 of aqueous alkali atroom temperature and pressure.

(i) Use the Data Booklet to calculate how many moles of NH3(g) were dissolved.

(ii) Write the equation for the neutralisation of aqueous ammonia by dilute sulphuricacid.

...................................................................................................................................

ForExaminer’s

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© UCLES 2004



5


(iii) Calculate the volume of 0.50 mol dm–3 sulphuric acid that is required to neutralisethe 200 cm3 of aqueous ammonia.

[3]

(d) In the boxes below, draw diagrams to show the shapes of an ammonia molecule and anammonium ion. Clearly show the bond angles on your diagrams.

[4]

(e) Ammonia does not burn in air but will burn in pure oxygen.

(i) Balance the equation for this reaction:

…… NH3(g) + …… O2(g) → …… N2(g) + …… H2O(g)

(ii) Use oxidation numbers to explain why this is a redox reaction.

...................................................................................................................................

...................................................................................................................................

...............................................................................................................................[3]

[Total : 16]

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© UCLES 2004

ammonia ammonium ion



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4 Esters are compounds which provide the flavour of many fruits and the perfumes of manyflowers.

(a) The ester CH3(CH2)2CO2CH3 contributes to the aroma of apples.

(i) State the reagents and conditions needed for the hydrolysis of this ester.

...................................................................................................................................

(ii) Write the equation for the hydrolysis of this ester.

...................................................................................................................................

(iii) Apart from their use as perfumes and food flavourings, state one major commercialuse of esters.

...............................................................................................................................[3]

(b) Leaf alcohol is a stereoisomer that can form when insects such as caterpillars eat greenleaves.

(i) Draw the other stereo-isomer of leaf alcohol.

(ii) Draw the structure for the ester formed when leaf alcohol reacts with ethanoic acid.Show all the bonds in the ester group.

[3]

(c) (i) Deduce the relative molecular mass, Mr, for leaf alcohol.

HO

CH2 CH3C C

CH2

H H

CH2

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© UCLES 2004



7

9701/02/M/J/04

(ii) Leaf alcohol was reacted to form a product with an Mr value 18 units less.

Suggest a structure for this product and deduce the type of reaction that tookplace.

structure of product.

type of reaction .....................................................................................................[3]

(d) Describe a simple chemical test to distinguish between leaf alcohol and your product in(c)(ii).

test ...................................................................................................................................

observation ...................................................................................................................[2]

[Total : 11]

5 A number of organic compounds containing the halogens fluorine and/or chlorine arecommercially important because of their chemical inertness.

(a) Name three such compounds, and for each state a use where its inertness is important.

(i) ...................................................................................................................................

...................................................................................................................................

(ii) ...................................................................................................................................

...................................................................................................................................

(iii) ...................................................................................................................................

...............................................................................................................................[6]

(b) Under certain conditions in the upper atmosphere, some of these compounds breakdown.

(i) Explain how this happens and what effects this has, in chemical terms.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) Suggest alternative compounds, which do not contain a halogen, for two of theuses you have given in (a).

...................................................................................................................................

...............................................................................................................................[5]

[Total : 11]

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BLANK PAGE

University of Cambridge International Examinations is part of the University of Cambridge Local Examinations Syndicate (UCLES) which is itself a department ofthe University of Cambridge.



This document consists of 10 printed pages and 2 blank pages.SP (MML 8078 3/04) S92060/2.1© UCLES 2005 [Turn over



CHEMISTRY

Paper 2 Structured Questions AS Core

9701/02

May/June 2005

1 hour 15 minutesCandidates answer on the Question Paper.Additional Materials: Data Booklet



Answer all questions.The number of marks is given in brackets [ ] at the end of each question or part question.You may lose marks if you do not show your working or if you do not use appropriate units.A Data Booklet is provided.You may use a calculator.

DO NOT WRITE IN THE BARCODE.

DO NOT WRITE IN THE GREY AREAS BETWEEN THE PAGES.For Examiner’s Use

4

3

2

1

5

TOTAL

Candidate

Name

Centre

Number

Candidate

Number



Answer all the questions in the space provided.

1 Iron and cobalt are adjacent elements in the Periodic Table. Iron has three main naturallyoccurring isotopes, cobalt has one.

(a) Explain the meaning of the term isotope.

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [2]

(b) The most common isotope of iron is 56Fe; the only naturally occurring isotope of cobaltis 59Co.

Use the Data Booklet to complete the table below to show the atomic structure of 56Feand of 59Co.

[3]

(c) A sample of iron has the following isotopic composition by mass.

(i) Define the term relative atomic mass.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) By using the data above, calculate the relative atomic mass of iron to threesignificant figures.

[5]

[Total: 10]

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ForExaminer’s

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isotope

isotope mass 54 56 57

5.84 91.68 2.17% by mass

protons

number of

neutrons electrons

56Fe

59Co



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3

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2 Sulphur and its compounds are found in volcanoes, in organic matter and in minerals.

Sulphuric acid, an important industrial chemical, is manufactured from sulphur by theContact process. There are three consecutive reactions in the Contact process which areessential.

(a) Write a balanced equation (using where appropriate) for each of these reactionsin the correct sequence.

1 .......................................................................................................................................

2 .......................................................................................................................................

3 ................................................................................................................................. [4]

(b) What catalyst is used?

.................................................................................................................................... [1]

Hydrogen sulphide, H2S, is a foul-smelling compound found in the gases from volcanoes.Hydrogen sulphide is covalent, melting at –85 °C and boiling at –60 °C.

(c) (i) Draw a ‘dot-and-cross’ diagram to show the structure of the H2S molecule.

(ii) Predict the shape of the H2S molecule.

.............................................................

(iii) Oxygen and sulphur are both in Group VI of the Periodic Table.

Suggest why the melting and boiling points of water, H2O, are much higher thanthose of H2S.

..................................................................................................................................

..................................................................................................................................

............................................................................................................................ [4]

4

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Hydrogen sulphide burns with a blue flame in an excess of oxygen to form sulphur dioxideand water.

(d) (i) Write a balanced equation for the complete combustion of H2S.

..................................................................................................................................

(ii) What is the change in the oxidation number of sulphur in this reaction?

from ....................................................... to .............................................................

(iii) What volume of oxygen, measured at room temperature and pressure, is requiredfor the complete combustion of 8.65 g of H2S? Give your answer to two decimalplaces.

[5]

Hydrogen sulphide is a weak diprotic (dibasic) acid. Its solution in water contains HS– and afew S2– ions.

(e) (i) What is meant by the term weak acid?

..................................................................................................................................

..................................................................................................................................

(ii) Write an equation, with state symbols, for the first ionisation of H2S when itdissolves in water.

............................................................................................................................ [3]

[Total: 17]

5

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ForExaminer’s

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3 Magnesium is the eighth most common element in the Earth’s crust.

The metal is widely used in alloys which are light and strong.

Some reactions of magnesium and its compounds are shown in the reaction schemebelow.

(a) Identify, by name or formula, compounds A to F.

A .......................................................

B .......................................................

C .......................................................

D .......................................................

E .......................................................

F ........................................................

[6]

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H2(g) + A(aq)

C(s)

dil. H2SO4

Na2CO3(aq) heat in air

heat

NaOH(aq)

dil. HNO3

heat

Mg(s)

D(s)

F(s)

dil. HCl

heat

evaporate

B(aq)

E(s)

F(aq)

+ H2(g)



(b) (i) Construct balanced equations for the following reactions.

magnesium to compound A

..................................................................................................................................

compound C to compound D

..................................................................................................................................

compound F to compound D

..................................................................................................................................

(ii) Suggest a balanced equation for the effect of heat on compound E.

............................................................................................................................ [4]

[Total: 10]

7


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4 Compound G, in which R– represents the rest of the molecule, was made for use as a teargas in World War 2.

Compound G was made by the following sequence of reactions.

stage I stage II stage IIIR–CH3 R–CH2Cl R–CH2CN R–CHBrCN

(a) (i) For stage I and for stage II, state the reagent(s) and condition(s) used to carry outeach change.

stage I reagent(s) ..................................................................................................

condition(s) ................................................................................................

stage II reagent(s) ..................................................................................................

condition(s) ................................................................................................

(ii) Suggest the reagent(s) and condition(s) necessary to carry out stage III.

reagent(s) .................................................................................................................

condition(s) ...............................................................................................................[6]

R

H

C

Br

CN

compound G

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Compound G was not actually used in World War 2 and stocks of it had to be destroyedsafely. The following sequence of reactions was used in this process.

stage IV stage VR–CHBrCN R–CHBrCO2H R–CH(OH)CO2H

stage VI

R–CH2CO2H

(b) For stage IV and for stage V state the reagent(s) and condition(s) necessary to bringabout each reaction.

stage IV reagent(s) .........................................................................................................

condition(s) ......................................................................................................

stage V reagent(s) .........................................................................................................

condition(s) ................................................................................................ [4]

(c) The full sequence of stages I to VI involves some compounds which contain chiralcentres.

(i) Explain what is meant by the term chiral centre.

..................................................................................................................................

..................................................................................................................................

(ii) Draw displayed formulae for the isomers of one compound in the full sequence ofstages I to VI which you consider to be chiral.

[3]

[Total: 13]

9


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5 A student obtained the following results when analysing an organic compound, H.

The student allowed test 5 to go to completion and then investigated the product of test 5with the following result.

(a) Calculate the molecular formula of H.

[2]

(b) What can be deduced about the nature of H by the following tests?

(i) test 3 ........................................................................................................................

(ii) test 4 ........................................................................................................................[2]

(c) (i) What functional group would have given a positive result in test 6?

..................................................................................................................................

(ii) What functional group is shown to be present in H by tests 5 and 6?

..................................................................................................................................[2]

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ForExaminer’s

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test observation

test 1

test 2

test 3

test 4

test 5

test 6

relative molecular mass 72

C, 66.7%; H, 11.1%; O, 22.2%

Br2 decolourised

H2(g) evolved

green colour observed

no reaction

% composition by mass

reactions with Br2(aq)

reaction with Na(s)

reaction with warm Cr2O72–/H+

reaction with 2,4-dinitrophenylhydrazine



ForExaminer’s

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(d) On testing a sample of H, the student found that it was not chiral.

H did, however, show cis-trans isomerism.

How does cis-trans isomerism arise in an organic molecule?

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [2]

(e) Use all of the information above to draw labelled, displayed formulae of thestereoisomers of compound H.

[2]

[Total: 10]

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12

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Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Everyreasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, thepublisher will be pleased to make amends at the earliest possible opportunity.

University of Cambridge International Examinations is part of the University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department ofthe University of Cambridge.



This document consists of 11 printed pages and 1 blank page.SP (CW) T15741/2© UCLES 2006 [Turn over



CHEMISTRY


9701/02

May/June 2006



Write your name, Centre number and candidate number on all the work you hand in.Write in dark blue or black pen in the spaces provided on the Question Paper.You may use a pencil for any diagrams, graphs, or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.

Answer all questions.You may lose marks if you do not show your working or if you do not use appropriate units.A Data Booklet is provided.You may use a calculator.The number of marks is given in brackets [ ] at the end of each question or part question.At the end of the examination, fasten all your work securely together.


DO NOT WRITE IN THE GREY AREAS BETWEEN THE PAGES. For Examiner’s Use

1

2

3

4

5

Total



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ForExaminer’s

Use

Answer all the questions in the spaces provided.

1 Mohr’s salt is a pale green crystalline solid which is soluble in water. Mohr’s salt is a ‘double salt’ which contains

two cations, one of which is Fe2+,

one anion which is SO42–,

and water of crystallisation.

(a) The identity of the second cation was determined by the following test. Solid Mohr’s salt was heated with solid sodium hydroxide and a colourless gas was

evolved. The gas readily dissolved in water giving an alkaline solution.

(i) What is the gas?

..................................................................................................................................

(ii) What is the formula of the second cation identified by this test?

..................................................................................................................................

(iii) In this test, a grey/green solid residue was also formed.

Suggest a name or formula for this solid.

.................................................................................................................................. [3]

(b) The identity of the anion present in Mohr’s salt was confirmed by adding dilute hydrochloric acid followed by aqueous barium chloride to an aqueous solution of Mohr’s salt. A white precipitate was formed.

Suggest the identity of the white precipitate.

......................................................................................................................................[1]

(c) When a double salt such as Mohr’s salt is made, the two individual salts are mixed together in a 1:1 molar ratio, dissolved in water and the solution crystallised.

(i) Give the formula of each of the two salts that would be mixed to make the double salt, Mohr’s salt.

salt 1 ...............................................

salt 2 ...............................................



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[Turn over

(ii) Calculate the relative formula mass of each of the salts present in Mohr’s salt.

salt 1

relative formula mass of salt 1 ..................................

salt 2

relative formula mass of salt 2 ..................................

(iii) The crystals of the double salt contain water of crystallisation.

The relative formula mass of Mohr’s salt is 392. Use your answers to (ii) to calculate the number of moles of water of crystallisation present in one mole of Mohr’s salt.

[6]

[Total: 10]



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2 The unsaturated hydrocarbon ethyne (acetylene), C2H2, is widely used in ‘oxy-acetylene torches’ for cutting and welding metals. In the torch, ethyne is burned in oxygen to produce a flame with a temperature of 3400 K.

(a) Ethyne is a linear molecule with a triple bond, C�C, between the two carbon atoms.

Draw a ‘dot-and-cross’ diagram of an ethyne molecule.

[1]

(b) When used for cutting or welding, ethyne is transported in cylinders which contain the gas under pressure. A typical cylinder has a volume of 76 dm3 and contains ethyne gas at 1515 kPa pressure at a temperature of 25 °C.

Use the general gas equation, pV = nRT, to calculate the amount, in moles, of ethyne in this cylinder.

[2]

(c) In some countries, ethyne is manufactured from calcium carbide, CaC2, which is produced by heating quicklime and coke together at 2300 K.

CaO + 3C CaC2 + CO

When water is added to the CaC2, calcium hydroxide, Ca(OH)2, and ethyne, C2H2, are produced.

(i) Construct a balanced equation for the formation of ethyne from calcium carbide.

..................................................................................................................................

(ii) Use this equation and your answer to part (b) to calculate the mass of CaC2 which will react with an excess of water to produce enough ethyne to fill 100 cylinders of the gas.

[3]



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(d) The equation for the complete combustion of ethyne is given below. Use appropriate bond energy data from the Data Booklet to calculate a value for the

enthalpy change of combustion of ethyne.

C2H2(g) + ⁵⁄₂O2(g) 2CO2(g) + H2O(g)

[3]

(e) The value for the standard enthalpy change of combustion of ethyne is –1300 kJ mol–1.

(i) Define the term standard enthalpy change of combustion.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Explain why your answer to (d) does not have the same value as the standard enthalpy change of combustion.

..................................................................................................................................

.................................................................................................................................. [3]

[Total: 12]



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3 This question is about the elements of Group VII, the halogens.

(a) Complete the following table.

halogen colourphysical state at

room temperature

chlorine

bromine

iodine [2]

(b) Concentrated sulphuric acid is added to separate solid samples of magnesium chloride, magnesium bromide, and magnesium iodide.

(i) Describe, in each case, one observation you would be able to make.

MgCl2 .......................................................................................................................

..................................................................................................................................

MgBr2 .......................................................................................................................

..................................................................................................................................

MgI2 ..........................................................................................................................

..................................................................................................................................

(ii) Give an equation for the reaction of concentrated sulphuric acid with magnesium chloride.

.................................................................................................................................. [4]

(c) When dilute nitric acid and aqueous silver nitrate are added to a solution of a magnesium halide, MgX2, a pale cream precipitate is formed.

This precipitate is soluble in concentrated aqueous ammonia but not soluble in dilute aqueous ammonia.

(i) What is the identity of the precipitate?

..................................................................................................................................

(ii) Give an equation, with state symbols, for the reaction of the precipitate with concentrated aqueous ammonia.

.................................................................................................................................. [3]



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(d) A hot glass rod is plunged into separate gas jars, one containing hydrogen chloride and one containing hydrogen iodide.

(i) For each gas, state what you would observe, if anything, and write an equation for any reaction that takes place.

HCl ...........................................................................................................................

..................................................................................................................................

HI .............................................................................................................................

..................................................................................................................................

(ii) Explain your answer to (i) in terms of enthalpy changes.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(iii) What is the role of the hot glass rod in any reaction that occurs?

..................................................................................................................................

.................................................................................................................................. [6]

[Total: 15]



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4 Compounds containing the allyl group, CH2=CHCH2− , have pungent smells and are found in onions and garlic.

Allyl alcohol, CH2=CHCH2OH, is a colourless liquid which is soluble in water.

(a) Allyl alcohol behaves as an alkene and as a primary alcohol.

Give the structural formula of the organic compound formed when allyl alcohol is

(i) reacted with Br2,

(ii) heated under reflux with an acidified solution of Cr2O72– ions.

[2]

(b) When allyl alcohol is reacted with MnO2 at room temperature, propenal, CH2=CHCHO is formed.

What type of reaction is this?

......................................................................................................................................[1]

(c) Allyl alcohol may be converted into propanal, CH3CH2CHO, by using a ruthenium(IV) catalyst in water.

CH2=CHCH2OH ruthenium(IV) catalyst CH3CH2CHO

The reactant and the product are isomers. What form of isomerism do they display?

......................................................................................................................................[1]



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(d) Allyl alcohol can be converted into propanal in two steps without the use of a ruthenium(IV) catalyst.

CH2=CHCH2OH step I

CH3CH2CH2OH step II

CH3CH2CHO

What reagents and conditions would be used for each step?

step I

reagent(s) ........................................................................................................................

condition(s) ......................................................................................................................

step II

reagent(s) ........................................................................................................................

condition(s) ..................................................................................................................[4]

(e) By considering your answers to (b) and (d), suggest what is unusual about the single-step reaction in (c).

..........................................................................................................................................

......................................................................................................................................[1]

(f) Suggest the structural formula of the organic compound formed when allyl alcohol is

(i) reacted with cold, dilute MnO4– ions,

(ii) heated under reflux with acidified MnO4– ions.

[3]

[Total: 12]



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5 Many organic reactions are substitution reactions in which the number of carbon atoms in the organic compound is unchanged.

(a) What is meant by the term substitution reaction?

..........................................................................................................................................

......................................................................................................................................[1]

(b) One example of a substitution reaction is the formation of an alcohol from a halogenoalkane.

(i) Write a balanced equation for the formation of ethanol from bromoethane.

..................................................................................................................................

(ii) State the conditions for this reaction.

..............................................................................................................................[2]

(c) In a few organic reactions, the product contains one more carbon atom than the starting material.

(i) Write the equation for a reaction in which the organic compound bromoethane, which contains two carbon atoms, is converted into an organic compound which contains three carbon atoms.

..................................................................................................................................

(ii) State the conditions for this reaction.

..............................................................................................................................[2]



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(d) Ethanol may be converted into propanoic acid in a three-stage process which uses ethanol as the only organic compound.

C2H5OH step I

K step II

L step III

C2H5CO2H

(i) Give the structural formulae of the intermediate compounds K and L.

K ...............................................................................................................................

L ...............................................................................................................................

(ii) State the reagent(s) used and give the essential condition(s) for step I and for step III.

step I

reagent(s) .................................................................................................................

condition(s) ...............................................................................................................

step III

reagent(s) .................................................................................................................

condition(s) ................................................................................................................ [6]

[Total: 11]



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SP (CW) T34786/3© UCLES 2007 [Turn over

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONSGeneral Certificate of Education Advanced Subsidiary Level and Advanced Level


Write your name, Centre number and candidate number on all the work you hand in.Write in dark blue or black pen.You may use a pencil for any diagrams, graphs, or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.DO NOT WRITE IN ANY BARCODES.

Answer all questions.You may lose marks if you do not show your working or if you do not use appropriate units.A Data Booklet is provided.The number of marks is given in brackets [ ] at the end of each question or part question.At the end of the examination, fasten all your work securely together.

DO NOT WRITE IN THE GREY AREAS BETWEEN THE PAGES.

*3713971972*

CHEMISTRY 9701/02

Paper 2 Structured Questions AS Core May/June 2007

1 hour 15 minutes

Candidates answer on the Question Paper.

Additional Materials: Data Booklet


1

2

3

4

Total



2

9701/02/M/J/07© UCLES 2007

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1 Ethene, C2H4, and hydrazine, N2H4, are hydrides of elements which are adjacent in the Periodic Table. Data about ethene and hydrazine are given in the table below.

C2H4 N2H4

meltingpoint/°C

–169 +2

boilingpoint/°C

–104 +114

solubility in water

insoluble high

solubility in ethanol

high high

(a) Ethene and hydrazine have a similar arrangement of atoms but differently shaped molecules.

(i) What is the H-C-H bond angle in ethene?

..................................................................................................................................

(ii) Draw a ‘dot-and-cross’ diagram for hydrazine.

(iii) What is the H-N-H bond angle in hydrazine?

..................................................................................................................................[4]

(b) The melting and boiling points of hydrazine are much higher than those of ethene. Suggest reasons for these differences in terms of the intermolecular forces each

compound possesses.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]



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(c) Explain, with the aid of a diagram showing lone pairs of electrons and dipoles, why hydrazine is very soluble in ethanol.

[3]

Ethene and hydrazine each react with HCl.

(d) When ethene is reacted with HCl, C2H5Cl is the only product.

(i) Using structural formulae, give an equation for the reaction between ethene and HCl.

(ii) What type of reaction occurs between HCl and ethene?

..................................................................................................................................

(iii) Explain why there is no further reaction between C2H5Cl and HCl.

..................................................................................................................................[3]

(e) When aqueous hydrazine is reacted with HCl, a solid compound of formula N2H5Cl may be isolated. When an excess of HCl is used, a second solid, N2H6Cl2, is formed.

(i) Suggest what type of reaction occurs between hydrazine and HCl.

..................................................................................................................................

(ii) What feature of the hydrazine molecule enables this reaction to occur?

..................................................................................................................................

(iii) Suggest why one molecule of hydrazine is able to react with one or two molecules of HCl.

..................................................................................................................................

..................................................................................................................................[3]

[Total: 16]



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2 Alcohols and esters are important organic compounds which are widely used as solvents.

Esters such as ethyl ethanoate can be formed by reacting carboxylic acids with alcohols.

CH3CO2H + C2H5OH CH3CO2C2H5 + H2O

This reaction is an example of a dynamic equilibrium.

(a) Explain what is meant by the term dynamic equilibrium.

..........................................................................................................................................

......................................................................................................................................[1]

(b) Write the expression for the equilibrium constant for this reaction, Kc.

[1]

(c) For this equilibrium, the value of Kc is 4.0 at 298 K. A mixture containing 0.5 mol of ethanoic acid, 0.5 mol ethanol, 0.1 mol ethyl ethanoate

and 0.1 mol water was set up and allowed to come to equilibrium at 298 K. The final volume of solution was V dm3.

Calculate the amount, in moles, of each substance present at equilibrium.

[4]



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[Turn over

Alcohols may be classified into primary, secondary and tertiary. Some reactions are common to all three types of alcohol. In other cases, the same reagent gives different products depending on the nature of the alcohol.

(d) In the empty squares below give the structural formula of the organic compound formed in each of the reactions indicated.

If no reaction occurs, write ‘no reaction’ in the space.

alcohol

reagent(s) andconditions

CH3CH2CH2CH2OH CH3CH2CH(OH)CH3 (CH3)3COH

red phosphorus and iodine

heat under reflux

concentrated H2SO4

heat

Cr2O72–/H+

heat under reflux

[5]

[Total: 11]



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3 This question is about the elements in Group II of the Periodic Table, magnesium to barium.

(a) Complete the table below to show the electronic configuration of calcium atoms and of strontium ions, Sr2+.

1s 2s 2p 3s 3p 3d 4s 4p 4d

Ca 2 2 6

Sr2+ 2 2 6

[2] (b) Explain the following observations.

(i) The atomic radii of Group II elements increase down the Group.

..................................................................................................................................

..................................................................................................................................

(ii) The strontium ion is smaller than the strontium atom.

..................................................................................................................................

..................................................................................................................................

(iii) The first ionisation energies of the elements of Group II decrease with increasing proton number.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

.................................................................................................................................. [4]



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[Turn over

(c) Samples of magnesium and calcium are placed separately in cold water and left for some time. In each case, describe what you would see and write a balanced equation for each reaction.

(i) magnesium

observation ...............................................................................................................

..................................................................................................................................

equation ................................................................................................................... (ii) calcium

observation ...............................................................................................................

..................................................................................................................................

equation ...................................................................................................................[6]

(d) Strontium nitrate, Sr(NO3)2 undergoes thermal decomposition.

(i) State one observation you would make during this reaction.

..................................................................................................................................

..................................................................................................................................

(ii) Write a balanced equation for this reaction.

.................................................................................................................................. [4]

[Total: 16]



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4 Commercial paint and varnish removers contain a mixture of dichloromethane, CH2Cl2, and methanol, CH3OH.

(a) What would be observed when the following reactions are carried out? In each case, give the name or formula of the reaction product which is responsible for

the observation you have made.

(i) CH2Cl2 is reacted with NaOH(aq) and AgNO3(aq) and the mixture left to stand.

observation ...............................................................................................................

product responsible ..................................................................................................

(ii) CH3OH is mixed with PCl5.

observation ...............................................................................................................

product responsible ..................................................................................................

(iii) CH3OH is reacted with sodium.

observation ...............................................................................................................

product responsible .................................................................................................. [6]

(b) When CH2Cl2 is heated under reflux with an excess of NaOH(aq), a compound W is formed.

W has the following composition by mass: C, 40.0%; H, 6.7%; O, 53.3%.

Use this information and the Data Booklet to show that the empirical formula of W is CH2O.

[2]



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(c) Compounds with the empirical formula CH2O can have the molecular formula C2H4O2.

Two possible structural formulae for compounds with molecular formula C2H4O2 are HCO2CH3 and H2C=C(OH)2.

In the boxes below, draw displayed formulae for three further structural isomers with the molecular formula C2H4O2.

Do not attempt to draw any structures containing rings or O–O bonds.

X

Y Z [3]

(d) Identify which of your compounds, X, Y, or Z, will react with the following reagents.

In each case, state what you would observe.

(i) solid NaHCO3

compound ............

observation ...............................................................................................................

(ii) Tollens’ reagent

compound ............

observation ............................................................................................................... [4]

(e) One of the three compounds, X, Y, or Z, shows stereoisomerism.

Draw displayed, labelled structures of the stereoisomers of this compound.

[2]

[Total: 17]



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Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity.

University of Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.




SP (SLM/CGW) T58865/2© UCLES 2008 [Turn over






*8522443878*

CHEMISTRY 9701/02

Paper 2 AS Structured Questions May/June 2008

1 hour 15 minutes




1

2

3

4

5

Total



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1 The structural formulae of water, methanol and methoxymethane, CH3OCH3, are given below.

O

H H

O

H3C H

O

H3C CH3

(a) (i) How many lone pairs of electrons are there around the oxygen atom in methoxymethane?

..................................................................................................................................

(ii) Suggest the size of the C–O–C bond angle in methoxymethane.

.................................................................................................................................. [2]

The physical properties of a covalent compound, such as its melting point, boiling point, vapour pressure, or solubility, are related to the strength of attractive forces between the molecules of that compound.

These relatively weak attractive forces are called intermolecular forces. They differ in their strength and include the following.

A interactions involving permanent dipoles

B interactions involving temporary or induced dipoles

C hydrogen bonds

(b) By using the letters A, B, or C, state the strongest intermolecular force present in each of the following compounds.

For each compound, write the answer on the dotted line.

ethanal CH3CHO ..............

ethanol CH3CH2OH ..............

methoxymethane CH3OCH3 ..............

2-methylpropane (CH3)2CHCH3 .............. [4]



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(c) Methanol and water are completely soluble in each other.

(i) Which intermolecular force exists between methanol molecules and water molecules that makes these two liquids soluble in each other?

..................................................................................................................................

(ii) Draw a diagram that clearly shows this intermolecular force. Your diagram should show any lone pairs or dipoles present on either molecule that you consider to be important.

[4]

(d) When equal volumes of ethoxyethane, C2H5OC2H5, and water are mixed, shaken, and then allowed to stand, two layers are formed.

Suggest why ethoxyethane does not fully dissolve in water. Explain your answer.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

[Total: 12]



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2 The Periodic Table we currently use is derived directly from that proposed by Mendeleev in 1869 after he had noticed patterns in the chemical properties of the elements he had studied.

The diagram below shows the first ionisation energies of the first 18 elements of the Periodic Table as we know it today.

2500He

H

Ne

Li Na

Ar

2000

1500

1000

500

2 4 6 8 101 3 5 7 12 14 179proton number

firstionisation

energy/kJ mol-1

11 13 15 16 180

(a) Give the equation, including state symbols, for the first ionisation energy of fluorine.

...................................................................................................................................... [2]

(b) Explain why there is a general increase in first ionisation energies from sodium to argon.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [3]

(c) (i) Explain why the first ionisation energy of aluminium is less than that of magnesium.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................



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(ii) Explain why the first ionisation energy of sulphur is less than that of phosphorus.

..................................................................................................................................

..................................................................................................................................

.................................................................................................................................. [4]

The table below refers to the elements sodium to sulphur and is incomplete.

element Na Mg Al Si P S

melting point high

conductivity high

(d) (i) Complete the ‘melting point’ row by using only the words ‘high’ or ‘low’.

(ii) Complete the ‘conductivity’ row by using only the words ‘high’, ‘moderate’ or ‘low’. [5]

(e) When Mendeleev published his Periodic Table, the elements helium, neon and argon were not included.

Suggest a reason for this.

..........................................................................................................................................

...................................................................................................................................... [1]

[Total: 15]



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3 When hydrocarbons such as petrol or paraffin wax are burned in an excess of air in a laboratory, carbon dioxide and water are the only products.

When petrol is burned in a car engine, nitrogen monoxide, NO, is also formed.

(a) Explain how NO is formed in an internal combustion engine but not formed when a small sample of petrol is burnt in an evaporating basin.

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

The engines of modern motor cars have exhaust systems which are fitted with catalytic converters in order to reduce atmospheric pollution from substances such as NO.

(b) (i) State three more pollutants, other than CO2 and H2O, that are present in the exhaust gases of a car engine.

.................................... and .................................... and ...........................................

(ii) What is the active material present in the catalytic converter?

..................................................................................................................................

(iii) Write one balanced equation to show how NO is removed from the exhaust gases of a car engine by a catalytic converter.

.................................................................................................................................. [4]

NO is also formed when nitrosyl chloride, NOCl, dissociates according to the following equation.

2NOCl (g) 2NO(g) + Cl2(g)

Different amounts of the three gases were placed in a closed container and allowed to come to equilibrium at 230 °C. The experiment was repeated at 465 °C.

The equilibrium concentrations of the three gases at each temperature are given in the table below.

concentration / mol dm–3

temperature / °C NOCl NO Cl 2

230 2.33 × 10–3 1.46 × 10–3 1.15 × 10–2

465 3.68 × 10–4 7.63 × 10–3 2.14 × 10–4



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(c) (i) Write the expression for the equilibrium constant, Kc , for this reaction. Give the units.

(ii) Calculate the value of Kc at each of the temperatures given.

230 °C

465 °C

(iii) Is the forward reaction endothermic or exothermic? Explain your answer.

..................................................................................................................................

.................................................................................................................................. [5]

(d) The temperature of the equilibrium was then altered so that the equilibrium concentrations of NOCl and NO were the same as each other.

What will be the effect on the equilibrium concentration of NOCl when the following changes are carried out on this new equilibrium? In each case, explain your answer.

(i) The pressure of the system is halved at constant temperature.

..................................................................................................................................

..................................................................................................................................

(ii) A mixture of NOCl(g) and NO(g) containing equal numbers of moles of each gas is introduced into the container at constant temperature.

..................................................................................................................................

.................................................................................................................................. [4]

[Total: 15]



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4 Two types of isomerism found in organic compounds are structural isomerism and cis-trans isomerism.

(a) Draw displayed formulae for

(i) two structural isomers of C2H4Br2,

D E

(ii) the cis- and the trans- isomers of C2H2Br2.

cis trans [4]

(b) (i) The cis- isomer of C2H2Br2 can be converted into one of the structural isomers of C2H4Br2. State the reagent(s) and conditions you would use to do this.

..................................................................................................................................

..................................................................................................................................

(ii) Which of your structural isomers, D or E, would be formed? Explain your answer.

isomer formed is .................

reason ....................................................................................................................... [3]

[Total: 7]



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5 Ethanedial (glyoxal) is used in the production of fabrics which have permanent creases.

O OC

H

ethanedial

C

H

Ethanedial undergoes many of the reactions of aldehydes.

(a) Ethanedial reacts with Tollens’ reagent.

(i) What would you see if you carried out this reaction?

..................................................................................................................................

(ii) What is the structural formula of the organic compound formed?

[2]

(b) Ethanedial reacts with hydrogen cyanide, HCN, to give compound F.

(i) What is the structural formula of F?

(ii) What type of reaction is this?

..................................................................................................................................

(iii) What is the structural formula of the compound formed when F is heated with an aqueous mineral acid such as dilute sulphuric acid?

[3]



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(c) Ethanedial can be oxidised and reduced.

(i) What is the structural formula of the organic compound formed when ethanedial is heated under reflux with an excess of acidified potassium dichromate(VI)?

(ii) What is the structural formula of the compound formed when ethanedial is reduced?

(iii) What reagent would be used for this reduction?

.................................................................................................................................. [3]

(d) When ethanedial is reacted with NaOH and the product treated with a mineral acid such as dilute sulphuric acid, the following reaction sequence takes place.

I CHOCHO + NaOH → HOCH2CO2Na

II HOCH2CO2Na + H+ → HOCH2CO2H + Na+

What type of reaction is the overall change?

...................................................................................................................................... [1]

(e) An isomer of ethanedial exists which reacts with sodium metal to give hydrogen.

Suggest the displayed formula of this isomer.

[2]

[Total: 11]



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Question Paper Mark Scheme Principal Examiner’s Report

Introduction Introduction Introduction

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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS

GCE Advanced Subsidiary Level and GCE Advanced Level

MARK SCHEME for the May/June 2009 question paper

for the guidance of teachers

9701 CHEMISTRY

9701/21 Paper 2 (AS Structured Questions), maximum raw mark 60

This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers.

Mark schemes must be read in conjunction with the question papers and the report on the examination.

• CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the May/June 2009 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.


maigna

First Variant Mark Scheme


Mark Scheme: Teachers’ version Syllabus Paper

GCE A/AS LEVEL – May/June 2009 9701 21

© UCLES 2009

1 (a) Al 1s2 2s22p6 3s23p1 (1) Ti 1s2 2s22p6 3s2 3p6 3d2 4s2 or 1s2 2s22p6 3s2 3p6 4s23d2 penalise any error (1) [2] (b) (i) pass chlorine gas (1) over heated aluminium (1) (ii) aluminium glows (1) white/yellow solid formed (1) chlorine colour disappears/fades (1) (any 2)

(iii) x x x x x Cl x

x x x • x x

x • x x

x Cl x Al x Cl x

x x • x x • x x

x x x x

x Cl x Al •

Cl x

x x • x x x

x x x Cl x x x

correct numbers of electrons, i.e.

3 • per Al atom and 7x per Cl atom

i.e. 6 • and 42 x in total (1) dative bond Cl to Al clearly shown by xx (1) [6] (c) chlorine is a strong/powerful oxidising agent (1) [1]


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© UCLES 2009

(d) (i) n(Ti) = 0.72 = 0.015 (1) 47.9 (ii) n(Cl) = (2.85 – 0.72) = 0.06 (1) 35.5 (iii) 0.015 : 0.06 = 1:4 empirical formula of A is TiCl4 Allow ecf on answers to (i) and/or (ii). (1)

(iv) Ti + 2Cl2 → TiCl4 (1) Allow ecf on answers to (iii). [4] (e) covalent/not ionic (1) simple molecular or mention of weak intermolecular forces or weak van der Waals’s forces between molecules (1) [2] [Total: 14 max]

2 (a) (i) Mg+(g) → Mg2+(g) + e– eqn. (1) state symbols (1) (ii) 736 + 1450 = +2186 kJ mol–1 (1) [3] (b) (i) dissolves (1) 6 – 7 (1) (ii) does not dissolve/slightly soluble (1) 8 – 11 (1) [4]

(c) (i) Mg3N2 + 6H2O → 3Mg(OH)2 + 2NH3 (1) (ii) Mg3N2 N is –3 (1) NH3 N is –3 (1) No because there is no change in the oxidation no. of N (1) [4] e.c.f on (c)(i) and values of oxidation numbers [Total: 11]


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© UCLES 2009

3 (a) 2CH3OH + 3O2 → 2CO2 + 4H2O (1) [1] (b) SO2 (1) NOx / NO2 / NO – not N2O (1) Pb compounds – not Pb (1) (any 2) If more than two answers are given any wrong ones will be penalised. [2] (c) low temperature (1) because forward reaction is exothermic (1) high pressure (1) because forward reaction goes to fewer molecules (1) or shows a reduction in volume increase [CO] or [H2] or remove CH3OH (1) correct explanation in terms of the effect of the change on the position of equilibrium or on the rate of reaction (1) (any two pairs) [4] (d) (i) removes CO2 (1) which causes greenhouse effect/global warming (1) (ii) CO2 + H2 CO + H2O initial moles 0.50 0.50 0.20 0.20 equil. moles (0.50-x) (0.50-x) (0.20+x) (0.20+x) (1) equil. concn. (0.50-x) (0.50-x) (0.20+x) (0.20+x) 1 1 1 1 Kc = [CO][H2O] (1) [CO2][H2] Kc = (0.20+x)2 = 1.44 (1) (0.50-x)2

gives x = 0.18 (1) at equilibrium, n(CO2) = n(H2) = 0.32 and n(CO) = n(H2O) = 0.38 (1) Allow ecf on wrong values of x that are less than 0.5. [7] [Total: 13 max]


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© UCLES 2009

4 (a) HCN Tollens’ reagent (1) dil. H2SO4 reduction (1) heat (1) (1) conc. H2SO4 (1) heat dil. cold dil. MnO4

–/H+

Cr2O7

2–/H+

heat under reflux (1) (1) one mark for each correct structure [6]

CH3CHO

CH3CH(OH)CN

B

CH3CO2H or CH3CO2

–

E

CH3CH(OH)CO2H

CH3CH2OH

D

CH2=CHCO2H

HOCH2CH(OH)CO2H

C

HO2CCOCO2H


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© UCLES 2009

(b) C + D HOCH2CH(OH)CO2C2H5 as minimum or H

HOCH2CCO2C2H5

OH (1) Allow e.c.f on candidate’s C and/or D. C + E CH2OCOCH3

CHOCOCH3

CO2H Allow either monoester. (1) [2] Allow e.c.f on candidate’s C and/or E. (c) CH3 CH3

C* *C H OH HO H

C≡N C≡N correct chiral carbon atom indicated (1)

one structure drawn fully displayed with C≡N (1) mirror object/mirror image pair correctly drawn in 3D (1) [3] [Total: 11] 5 (a) CH3COCH2C(CH3)2

or (by addition of one molecule of (CH3)2CO

across the >C=O bond of another) OH CH3COCHCH(CH3)2 (by working backwards from G and adding

one molecule of H2O across the C=C bond) OH (1) [1]


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© UCLES 2009

(b)

functional group in G reagent used in test what would be seen

alkene ......................................or carbonyl

Br2 or KMnO4(aq) ...................................... or 2,4-dinitrophenylhydrazine/ Brady’s reagent

decolourised ...................................... or yellow/orange/red colour or ppt.

(1) (1) (1) [3] (c) (i) dehydration/elimination (1) (ii) Al2O3 / P4O10 / conc. H2SO4/ conc.H3PO4 (1) [2] (d) NaBH4 or LiAlH4 (1) in water or methanol/ethanol or in dry ether (1) [2] or mixture of alcohol and water not ether Solvent mark is only awarded if reagent is correct. (e) CH3CO H CH3CO CH3

C=C C=C H3C CH3 H3C H

cis* trans** * allow this to be called Z ** allow this to be called E

or CH3CO C2H5 CH3CO H

C=C C=C H H H C2H5

cis* trans** * allow this to be called Z ** allow this to be called E


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© UCLES 2009

or CH3COCH2 CH3 CH3COCH2 H C=C C=C H H H CH3

cis or Z trans or E

two structures (1) correct cis and trans (1) explanation (1) [3] For cis and trans answers, the explanation should be in terms of the methyl groups (first pair

of isomers) or hydrogen atoms (second and third pairs of isomers) being on the same or opposite sides relative to the C=C bond.

For E/Z answers, the explanation will need to involve the relative sizes of the CH3C- group

and the CH3- group. This really only affects the first pair of isomers. [Total: 11]


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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS

GCE Advanced Subsidiary Level and GCE Advanced Level

MARK SCHEME for the May/June 2009 question paper

for the guidance of teachers

9701 CHEMISTRY

9701/22 Paper 22 (AS Structured Questions), maximum raw mark 60

This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers.

Mark schemes must be read in conjunction with the question papers and the report on the examination.

• CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the May/June 2009 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.


maigna

Second Variant Mark Scheme




© UCLES 2009

1 (a) Al 1s2 2s22p6 3s23p1 (1) Ti 1s2 2s22p6 3s2 3p6 3d2 4s2 or 1s2 2s22p6 3s2 3p6 4s23d2 penalise any error (1) [2] (b) (i) pass chlorine gas (1) over heated aluminium (1) (ii) aluminium glows (1) white/yellow solid formed (1) chlorine colour disappears/fades (1) (any 2) (iii)

x x x x x Cl x

x x x • x x

x • x x

x Cl x Al x Cl x

x x • x x • x x

x x x x

x Cl x Al •

Cl x

x x • x x x

x x x Cl x x x

correct numbers of electrons, i.e.

3 • per Al atom and 7x per Cl atom

i.e. 6 • and 42 x in total (1) dative bond Cl to Al clearly shown by xx (1) [6] (c) chlorine is a strong/powerful oxidising agent (1) [1]


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© UCLES 2009

(d) (i) n(Ti) = 47.9

0.72 = 0.015 (1)

(ii) n(Cl) = ( )

35.5

0.722.85 − = 0.06 (1)

(iii) 0.015 : 0.06 = 1:4 empirical formula of A is TiCl4 Allow ecf on answers to (i) and/or (ii). (1)

(iv) Ti + 2Cl2 → TiCl4 (1) Allow ecf on answers to (iii). [4] (e) covalent/not ionic (1) simple molecular or mention of weak intermolecular forces or weak van der Waals’s forces between molecules (1) [2] [Total: 14 max]

2 (a) (i) Ca+(g) → Ca2+(g) + e– equation (1) state symbols (1) (ii) 590 + 1150 = +1740 kJ mol–1 (1) [3] (b) (i) dissolves/vigorous reaction/ white or steamy fumes of HCl (1) 0 – 4 (1) (ii) dissolves/vigorous reaction (1) 0 – 4 (1) [4]

(c) (i) P4S10 + 16H2O → 4H3PO4 + 10H2S (1) (ii) P4S10 P is +5 (1) H3PO4 P is +5 (1) No because there is no change in the oxidation no. of P (1) ecf on answer to (c)(i) and on calculated oxidation numbers [4] [Total: 11]


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© UCLES 2009

3 (a) 2CH3OH + 3O2 → 2CO2 + 4H2O (1) [1] (b) SO2 (1) NOx / NO2 / NO – not N2O (1) Pb compounds – not Pb (1) (any 2) if more than two answers are given any wrong ones will be penalised [2] (c) low temperature (1) because forward reaction is exothermic (1) high pressure (1) because forward reaction goes to fewer molecules (1) or shows a reduction in volume increase [CO] or [H2] or remove CH3OH (1) correct explanation in terms of the effect of the change on the position of equilibrium or on the rate of reaction (1) (any two pairs) [4] (d) (i) removes CO2 (1) which causes greenhouse effect/global warming (1) (ii) CO2 + H2 CO + H2O initial moles 0.50 0.50 0.20 0.20 equil. moles (0.50-x) (0.50-x) (0.20+x) (0.20+x) (1) equil. concn. (0.50-x) (0.50-x) (0.20+x) (0.20+x) 1 1 1 1 Kc = [CO][H2O] (1) [CO2][H2] Kc = (0.20+x)2 = 1.44 (1) (0.50-x)2

gives x = 0.18 (1) at equilibrium, n(CO2) = n(H2) = 0.32 and n(CO) = n(H2O) = 0.38 (1) Allow ecf on wrong values of x that are less than 0.5. [7] [Total: 13 max]


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© UCLES 2009

4 (a) NaBH4 HCN dil PCl5 H2SO4 heat CCCCCCC conc. H2SO4 170°C Br2 (each correct structure gets 1 mark) [6]

CH3COCH3

CH3CH(OH)CH3

V

OH

CH3CCH3

CN

X

CH3CHClCH3

W

CH3C=CH2

CO2H

Br

CH3CCH2Br

CO2H

Z

OH

CH3CCH3

CO2H

Y


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© UCLES 2009

(b) (i) Z allow ecf on candidate’s Z or other chiral compound (1) (ii)

Br Br

H—C—H H—C—H

C* C* Br Br

H—C—H H—C—H

O=C C=O

H H OH OH chiral centre clearly shown by * (1) one structure drawn fully displayed especially –CO2H group (1) mirror object/mirror image pair correctly drawn in 3D (1) [4] (c) (i) Y + V CH3 CH3

CH3—C—CO2—C—H or (CH3)2C(OH)CO2CH(CH3)2

OH CH3 allow ecf on candidate’s Y and/or V (1) (ii) Y + Z CH3 CH3

Br—C—CO2—C—CO2H or CH3C(CH2Br)BrCO2C(CH3)2CO2H

CH2Br CH3 allow ecf on candidate’s Y and/or Z (1) [2] [Total: 11 max]


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© UCLES 2009

5 (a) CH3CH(OH)CH2CHO (by addition of one molecule of CH3CHO across the >C=O bond of another) or CH3CH2CH(OH)CHO (by working backwards from U and adding one molecule of H2O across the C=C bond ‘the other way’) (1) [1] (b)

functional group in U reagent used in test what would be seen

alkene ......................................or carbonyl not ketone ......................................or aldehyde

Br2 or KMnO4(aq) ...................................... or 2,4-dinitrophenylhydrazine/ Brady’s reagent ...................................... or Tollens’ reagent or Fehling’s solution

decolourised ...................................... or yellow/orange/red colour or ppt. ...................................... or silver ppt./mirror black colour or brick red ppt.

(1) (1) (1) [3] (c) (i) dehydration/elimination (1) (ii) Al2O3/P4O10/conc. H2SO4/conc. H3PO4 (1) [2] (d) NaBH4 or LiAlH4 (1) in water or methanol or ethanol or in dry ether (1) or mixture of water and alcohol not ether Solvent mark is only to be awarded if reagent is correct. [2]


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© UCLES 2009

5 (e) H

H C—H H H

C=C H C=C H

H C=O H C—C=O

H H H two structures (1) + (1) [2] CH3CH2CH(OH)CH2CHO or CH3CH(OH)CH(CH3)CHO allow CH3CH(OH)CH2CH2CHO (1) [1] [Total: 11]


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Location Entry Codes As part of CIE’s continual commitment to maintaining best practice in assessment, CIE uses different variants of some question papers for our most popular assessments with large and widespread candidature. The question papers are closely related and the relationships between them have been thoroughly established using our assessment expertise. All versions of the paper give assessment of equal standard. The content assessed by the examination papers and the type of questions is unchanged. This change means that for this component there are now two variant Question Papers, Mark Schemes and Principal Examiner’s Reports where previously there was only one. For any individual country, it is intended that only one variant is used. This document contains both variants which will give all Centres access to even more past examination material than is usually the case. The diagram shows the relationship between the Question Papers, Mark Schemes and Principal Examiners’ Reports that are available. Question Paper

Mark Scheme Principal Examiner’s Report

Introduction

Introduction Introduction

First variant Question Paper

First variant Mark Scheme First variant Principal Examiner’s Report

Second variant Question Paper

Second variant Mark Scheme

Second variant Principal Examiner’s Report

Who can I contact for further information on these changes? Please direct any questions about this to CIE’s Customer Services team at: [email protected] The titles for the variant items should correspond with the table above, so that at the top of the first page of the relevant part of the document and on the header, it has the words:

• First variant Question Paper / Mark Scheme / Principal Examiner’s Report

or

• Second variant Question Paper / Mark Scheme / Principal Examiner’s Report

as appropriate.




SJF4799/DT T65099/2© UCLES 2009 [Turn over




Answer all questions.You may lose marks if you do not show your working or if you do not use appropriate units.A Data Booklet is provided.

The number of marks is given in brackets [ ] at the end of each question or part question.At the end of the examination, fasten all your work securely together.


*1998330602*

CHEMISTRY 9701/21


1 hour 15 minutes




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1 Copper and titanium are each used with aluminium to make alloys which are light, strong and resistant to corrosion.

Aluminium, Al, is in the third period of the Periodic Table; copper and titanium are both transition elements.

(a) Complete the electronic configuration of aluminium and of titanium, proton number 22.

Al 1s2

Ti 1s2

[1]

Aluminium reacts with chlorine.

(b) (i) Outline how, starting from aluminium powder, this reaction could be carried out in a school or college laboratory to give a small sample of aluminium chloride. A diagram is not necessary.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Describe what you would see during this reaction.

..................................................................................................................................

..................................................................................................................................

(iii) At low temperatures, aluminium chloride vapour has the formula Al2Cl6. Draw a ‘dot-and-cross’ diagram to show the bonding in Al2Cl6. Show outer electrons only. Represent the aluminium electrons by . Represent the chlorine electrons by x.

[6]



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Copper forms two chlorides, CuCl and CuCl2.

(c) When copper is reacted directly with chlorine, only CuCl2 is formed. Suggest an explanation for this observation.

..........................................................................................................................................

..................................................................................................................................... [1]

Titanium also reacts with chlorine.

(d) When an excess of chlorine was reacted with 0.72 g of titanium, 2.85 g of a chloride A was formed.

(i) Calculate the amount, in moles, of titanium used.

(ii) Calculate the amount, in moles, of chlorine atoms that reacted.

(iii) Hence, determine the empirical formula of A.

(iv) Construct a balanced equation for the reaction between titanium and chlorine.

.................................................................................................................................. [4]

(e) At room temperature, the chloride of titanium, A, is a liquid which does not conduct electricity.

What does this information suggest about the bonding and structure in A?

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

[Total: 14]



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2 Magnesium will react on heating with chlorine, or oxygen, or nitrogen to give the chloride, or oxide, or nitride respectively. Each of these compounds is ionic and in them magnesium has the same +2 oxidation state.

(a) (i) Write an equation, with state symbols, for the second ionisation energy of

magnesium.

..................................................................................................................................

(ii) Use the Data Booklet to calculate the enthalpy change that occurs when one mole of gaseous magnesium ions, Mg2+, is formed from one mole of gaseous magnesium atoms.

Include a sign in your answer.

enthalpy change = ……………… kJ mol–1

[3]

(b) Separate samples of magnesium chloride and magnesium oxide are shaken with water. In each case, describe what you would see when this is done, and state the approximate pH of the water after the solid has been shaken with it.

(i) magnesium chloride

observation ...............................................................................................................

approximate pH of the water …………………

(ii) magnesium oxide

observation ...............................................................................................................

approximate pH of the water ………………… [4]



5


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(c) Magnesium burns in nitrogen to give magnesium nitride, a yellow solid which has the formula Mg3N2.

Magnesium nitride reacts with water to give ammonia and magnesium hydroxide.

(i) Construct an equation for the reaction of magnesium nitride with water.

..................................................................................................................................

(ii) Does a redox reaction occur when magnesium nitride reacts with water?

Use the oxidation numbers of nitrogen to explain your answer.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[4]

[Total: 11]



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3 Concern over the ever-increasing use of fossil fuels has led to many suggestions for alternative sources of energy. One of these, suggested by Professor George Olah, winner of a Nobel Prize in chemistry, is to use methanol, CH3OH, which can be obtained in a number of different ways.

Methanol could be used instead of petrol in a conventional internal combustion engine or used to produce electricity in a fuel cell.

(a) Construct a balanced equation for the complete combustion of methanol.

..................................................................................................................................... [1]

When hydrocarbon fuels are completely burned in an internal combustion engine, several toxic pollutants may be formed.

(b) State two toxic pollutants that can be produced after complete combustion of a hydrocarbon fuel in an internal combustion engine.

..........................................................................................................................................

..................................................................................................................................... [2]

Methanol may be manufactured catalytically from synthesis gas, a mixture of CO, CO2 and H2. The CO is reacted with H2 to form methanol, CH3OH.

CO(g) + 2H2(g) CH3OH(g) ΔH = –91 kJ mol-1

(c) From your understanding of Le Chatelier’s principle, state two conditions that could be used in order to produce a high yield of methanol.

In each case, explain why the yield would increase.

condition 1 .......................................................................................................................

explanation ......................................................................................................................

..........................................................................................................................................

condition 2 .......................................................................................................................

explanation ......................................................................................................................

..................................................................................................................................... [4]



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Carbon monoxide, which can be used to make methanol, may be formed by reacting carbon dioxide with hydrogen.

CO2(g) + H2(g) CO(g) + H2O(g) Kc = 1.44 at 1200 K

(d) (i) It has been suggested that, on a large scale, this reaction could be helpful to the environment.

Explain, with reasons, why this would be the case.

..................................................................................................................................

..................................................................................................................................

(ii) A mixture containing 0.50 mol of CO2, 0.50 mol of H2, 0.20 mol of CO and 0.20 mol of H2O was placed in a 1.0 dm3 flask and allowed to come to equilibriumat 1200 K.

Calculate the amount, in moles, of each substance present in the equilibrium mixture at 1200 K.

CO2 + H2 CO + H2O

initial 0.50 0.50 0.20 0.20 moles

[6]

[Total: 13]



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ForExaminer’s

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4 (a) Complete the following reaction scheme which starts with ethanal.

In each empty box, write the structural formula of the organic compound that would be formed.

B

dilute H2SO4

heat

D

conc. H2SO4

heat

CH2=CHCO2H

C

HCNTollens’reagent

reduction

E

CH3CHO

heat under reflux

[6]



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(b) Write the structural formula for the organic compound formed when, under suitable conditions,

(i) compound C reacts with compound D,

(ii) compound C reacts with compound E.

[2]

(c) Compound B is chiral. Draw displayed formulae of the two optical isomers of compound B, indicating with an asterisk (*) the chiral carbon atom.

[3]

[Total: 11]



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5 Propanone, CH3COCH3, an important industrial solvent, can be converted into another industrially important solvent, MIBK, by the following sequence.

2 CH3C=O C6H12O2

CH3F

step I step II

step III

CH3 C=O

CH=C(CH3)2

(C6H10O)

CH3C=O

CH2CH(CH3)2

G

MIBK

(a) When F is formed in step I no other compound is produced. Suggest a structural formula for F, which contains one –OH group.

[1] (b) Compound G has two functional groups.

Name one functional group present in G and show how you would identify it. Put your answers in the table.

functional group in G reagent used in test what would be seen

[3]

(c) G is formed from F in step II. Use your answers to (a) and (b) to suggest

(i) what type of reaction occurs in step II,

............................................................

(ii) a reagent for step II.

............................................................ [2]



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(d) The production of MIBK from G in step III involves the hydrogenation of the >C=C< group and is carried out catalytically. A mixture of compounds is formed because the >C=O group is also reduced.

What reagent(s) and solvent are normally used in a laboratory to reduce a >C=O group without reducing a >C=C< group present in the same molecule?

reagent(s) ........................................................................................................................

solvent ......................................................................................................................... [2]

G has a number of structural isomers.

(e) Draw the displayed formulae of a pair of structural isomers of G which contain the CH3CO– group and which exhibit cis-trans isomerism.

Label each structure cis or trans and give your reasoning.

[3]

[Total: 11]



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SP (CW) V04258/2© UCLES 2009 [Turn over







*1601384786*

CHEMISTRY 9701/22


1 hour 15 minutes




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9701/22/M/J/09© UCLES 2009

ForExaminer’s

Use


1 Copper and titanium are each used with aluminium to make alloys which are light, strong and resistant to corrosion.

Aluminium, Al, is in the third period of the Periodic Table; copper and titanium are both transition elements.

(a) Complete the electronic configuration of aluminium and of titanium, proton number 22.

Al 1s2

Ti 1s2

[1]

Aluminium reacts with chlorine.

(b) (i) Outline how, starting from aluminium powder, this reaction could be carried out in a school or college laboratory to give a small sample of aluminium chloride. A diagram is not necessary.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Describe what you would see during this reaction.

..................................................................................................................................

..................................................................................................................................

(iii) At low temperatures, aluminium chloride vapour has the formula Al2Cl6. Draw a ‘dot-and-cross’ diagram to show the bonding in Al2Cl6. Show outer electrons only. Represent the aluminium electrons by . Represent the chlorine electrons by x.

[6]



3


ForExaminer’s

Use

Copper forms two chlorides, CuCl and CuCl2.

(c) When copper is reacted directly with chlorine, only CuCl2 is formed. Suggest an explanation for this observation.

..........................................................................................................................................

..................................................................................................................................... [1]

Titanium also reacts with chlorine.

(d) When an excess of chlorine was reacted with 0.72 g of titanium, 2.85 g of a chloride A was formed.

(i) Calculate the amount, in moles, of titanium used.


(iii) Hence, determine the empirical formula of A.

(iv) Construct a balanced equation for the reaction between titanium and chlorine.

.................................................................................................................................. [4]

(e) At room temperature, the chloride of titanium, A, is a liquid which does not conduct electricity.

What does this information suggest about the bonding and structure in A?

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

[Total: 14]



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ForExaminer’s

Use

2 Phosphorus is a very reactive non-metallic element which readily forms ionic compounds with metals such as calcium and covalent compounds with non-metals such as chlorine and oxygen.

(a) (i) Write an equation, with state symbols, for the second ionisation energy of calcium.

..................................................................................................................................

(ii) Use the Data Booklet to calculate the enthalpy change that occurs when one mole of gaseous calcium ions, Ca2+, is formed from one mole of gaseous calcium atoms.

Include a sign in your answer.

enthalpy change = ..................... kJ mol–1 [3]

(b) Separate small samples of phosphorus(V) chloride and phosphorus(V) oxide are shaken with water. In each case, describe what you would see when this is done, and state the approximate pH of the water after the solid has been shaken with it.

(i) phosphorus(V) chloride

observation ...............................................................................................................

approximate pH of the water ..............

(ii) phosphorus(V) oxide

observation ...............................................................................................................

approximate pH of the water .............. [4]



5


ForExaminer’s

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(c) When phosphorus is heated with an excess of sulfur in an inert atmosphere, a pale yellow solid, with formula P4S10 is formed.

P4S10 reacts with water to give phosphoric acid, H3PO4, and hydrogen sulfide, H2S.

(i) Complete the equation for the reaction of P4S10 with water.

P4S10 + 16H2O

(ii) Does a redox reaction occur when P4S10 reacts with water? Use the oxidation numbers of phosphorus to explain your answer.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

............................................................................................................................. [4]

[Total: 11]



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ForExaminer’s

Use

3 Concern over the ever-increasing use of fossil fuels has led to many suggestions for alternative sources of energy. One of these, suggested by Professor George Olah, winner of a Nobel Prize in chemistry, is to use methanol, CH3OH, which can be obtained in a number of different ways.

Methanol could be used instead of petrol in a conventional internal combustion engine or used to produce electricity in a fuel cell.

(a) Construct a balanced equation for the complete combustion of methanol.

..................................................................................................................................... [1]

When hydrocarbon fuels are completely burned in an internal combustion engine, several toxic pollutants may be formed.

(b) State two toxic pollutants that can be produced after complete combustion of a hydrocarbon fuel in an internal combustion engine.

..........................................................................................................................................

..................................................................................................................................... [2]

Methanol may be manufactured catalytically from synthesis gas, a mixture of CO, CO2 and H2. The CO is reacted with H2 to form methanol, CH3OH.

CO(g) + 2H2(g) CH3OH(g) ΔH = –91 kJ mol–1

(c) From your understanding of Le Chatelier’s principle, state two conditions that could be used in order to produce a high yield of methanol.

In each case, explain why the yield would increase.

condition 1 .......................................................................................................................

explanation ......................................................................................................................

..........................................................................................................................................

condition 2 .......................................................................................................................

explanation ......................................................................................................................

..................................................................................................................................... [4]



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Carbon monoxide, which can be used to make methanol, may be formed by reacting carbon dioxide with hydrogen.

CO2(g) + H2(g) CO(g) + H2O(g) Kc = 1.44 at 1200 K

(d) (i) It has been suggested that, on a large scale, this reaction could be helpful to the environment.

Explain, with reasons, why this would be the case.

..................................................................................................................................

..................................................................................................................................

(ii) A mixture containing 0.50 mol of CO2, 0.50 mol of H2, 0.20 mol of CO and 0.20 mol of H2O was placed in a 1.0 dm3 flask and allowed to come to equilibrium at 1200 K.

Calculate the amount, in moles, of each substance present in the equilibrium mixture at 1200 K.

CO2 + H2 CO + H2O

initial 0.50 0.50 0.20 0.20 moles

[6]

[Total: 13]



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Use

4 (a) Complete the following reaction scheme which starts with propanone. In each empty box, write the structural formula of the organic compound that would

be formed.

V

NaBH4 CH3COCH3HCN

X

PCl5

dilH2SO4heat

W Y

conc.H2SO4170 °C

Br2

Z

[6]



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ForExaminer’s

Use

(b) One of the compounds V, W, X, Y or Z is chiral.

(i) Identify this compound by its letter.

............

(ii) Draw displayed formulae of the two optical isomers of this compound. Indicate with an asterisk (*) the chiral carbon atom.

[3]

(c) Write the structural formula for the organic compound formed when, under suitable conditions,

(i) compound Y reacts with compound V,

(ii) compound Y reacts with compound Z.

[2]

[Total: 11]



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ForExaminer’s

Use

5 Ethanal, CH3CHO, can be converted into compound U by the following sequence.

step I step II

2 CH3CHO C4H8O2 CH3CH=CHCHO

T U, C4H6O

(a) When T is formed in step I, no other compound is produced.

Suggest a structural formula for T which contains one –OH group in its molecule.

[1]

(b) Compound U has two functional groups.

You are to name one functional group present in U and show how you would identify it. Put your answers in the table.

functional group in U reagent used in test what would be seen

[3]

(c) U is formed from T in step II. Use your answers to (a) and (b) to suggest

(i) what type of reaction occurs in step II,

............................................................

(ii) a reagent for step II.

............................................................ [2]



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(d) Compound U can be converted into CH3CH=CHCH2OH.

What reagent(s) and solvent are normally used in a laboratory to reduce a >C=O group without reducing a >C=C< group present in the same molecule?

reagent(s) ........................................................................................................................

solvent ........................................................................................................................ [2]

U has three structural isomers.

(e) Draw the displayed formulae of two structural isomers of U that each contain the same functional groups as U.

[2]

(f) When a mixture of ethanal and propanal is reacted under the same conditions as in step I above, a similar reaction occurs with the formation of compound S, C5H10O2.

CH3CHO + CH3CH2CHO C5H10O2

Suggest a structural formula for S.

[1]

[Total: 11]



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DC (SHW 00422 3/09) 11740/2© UCLES 2010 [Turn over



Write your name, Centre number and candidate number on all the work you hand in.Write in dark blue or black pen.You may use a pencil for any diagrams, graphs, or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.DO NOT WRITE ON ANY BARCODES.



*1565076543*

CHEMISTRY 9701/21


1 hour 15 minutes




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9701/21/M/J/10© UCLES 2010

ForExaminer’s

Use


1 Elements and compounds which have small molecules usually exist as gases or liquids.

(a) Chlorine, Cl 2, is a gas at room temperature whereas bromine, Br 2, is a liquid under the same conditions.

Explain these observations.

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [2]

(b) The gases nitrogen, N2, and carbon monoxide, CO, are isoelectronic, that is they have the same number of electrons in their molecules.

Suggest why N2 has a lower boiling point than CO.

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [2]

(c) A ‘dot-and-cross’ diagram of a CO molecule is shown below. Only electrons from outer shells are represented.

C O

In the table below, there are three copies of this structure. On the structures, draw a circle round a pair of electrons that is associated with each of

the following.

(i) a co-ordinate bond (ii) a covalent bond (iii) a lone pair

C O C O C O

[3]

2



3


ForExaminer’s

Use

(d) Hydrogen cyanide, HCN, is a gas which is also isoelectronic with N2 and with CO. Each molecule contains a strong triple bond with the following bond energies.

bond bond energy / kJ mol–1

–C�N in HCN 890

N�N 994

C�O 1078

Although each compound contains the same number of electrons and a strong triple bond in its molecule, CO and HCN are both very reactive whereas N2 is not.


..........................................................................................................................................

.................................................................................................................................... [1]

(e) HCN reacts with ethanal, CH3CHO.

(i) Give the displayed formula of the organic product formed.

(ii) What type of reaction is this?

...................................................................

(iii) Draw the mechanism of this reaction. You should show all full and partial charges and represent the movement of electron pairs by curly arrows.

[5]

[Total: 13]



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2 The diagram below shows, for a given temperature T, a Boltzmann distribution of the kinetic energy of the molecules of a mixture of two gases that will react together, such as nitrogen and hydrogen.

The activation energy for the reaction, Ea, is marked.

Ea energy

number ofmolecules

(a) On the graph above,

(i) draw a new distribution curve, clearly labelled T�, for the same mixture of gases at a higher temperature, T�;

(ii) mark clearly, as H, the position of the activation energy of the reaction at the higher temperature, T�.

[3]

(b) Explain the meaning of the term activation energy.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [2]



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The reaction between nitrogen and hydrogen to produce ammonia in the Haber process is an example of a large-scale gaseous reaction that is catalysed.

(c) (i) State the catalyst used and give the operating temperature and pressure of the Haber process.

catalyst ......................................................

temperature ...............................................

pressure ....................................................

(ii) On the energy axis of the graph opposite, mark the position, clearly labelled C, of the activation energy of the reaction when a catalyst is used.

(iii) Use your answer to (ii) to explain how the use of a catalyst results in reactions occurring at a faster rate.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[3]

(d) Two reactions involving aqueous NaOH are given below.

CH3CHBrCH3 + NaOH CH3CH(OH)CH3 + NaBr reaction 1

HCl + NaOH NaCl + H2O reaction 2

In order for reaction 1 to occur, the reagents must be heated together for some time. On the other hand, reaction 2 is almost instantaneous at room temperature.

Suggest brief explanations why the rates of these two reactions are very different.

reaction 1 ........................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

reaction 2 ........................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [4]

[Total: 12]



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3 This question refers to the elements shown in the portion of the Periodic Table given below.

H HeLi Be B C N O F Ne

Na Mg Al Si P S Cl ArK Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

(a) From this table, identify in each case one element that has the property described. Give the symbol of the element in each case.

(i) The element that has a molecule which contains exactly eight atoms.

............................................................

(ii) The element that forms the largest cation.

............................................................

(iii) An element that floats on water and reacts with it.

............................................................

(iv) An element that reacts with water to give a solution that can behave as an oxidising agent.

............................................................

(v) An element whose nitrate gives a brown gas on thermal decomposition.

............................................................[5]



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(b) (i) Give the formula of the oxide of the most electronegative element.

............................................................

(ii) Several of these elements form more than one acidic oxide. Give the formulae of two such oxides formed by the same element.

.......................... and .........................[3]

The formulae and melting points of the fluorides of the elements in Period 3, Na to Cl, are given in the table.

formula of fluoride NaF MgF2 Al F3 SiF4 PF5 SF6 Cl F5

m.p. / K 1268 990 1017 183 189 223 170

(c) (i) Suggest the formulae of two fluorides that could possibly be ionic.

..................................................................................................................................

(ii) What is the shape of the SF6 molecule?

............................................................

(iii) In the sequence of fluorides above, the oxidation number of the elements increases from NaF to SF6 and then falls at Cl F5.

Attempts to make Cl F7 have failed but IF7 has been prepared. Suggest an explanation for the existence of IF7 and for the non-existence of Cl F7.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[4]

[Total: 12]



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4 (a) Complete the following reaction scheme which starts with propene. In each empty box, write the structural formula of the organic compound that would

be formed.

A

CH3CH=CH2KMnO4 /H+Br2

cold, dilute

NH3

in an excess

KCN in

aqueousethanol

B

D C F

E G

H2SO4(aq)heat under

reflux

NaOH(in ethanol)heat under

reflux

HBr

[7]



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(b) Under suitable conditions, compound E will react with compound B.

(i) What functional group is produced in this reaction?

............................................................

(ii) How is this reaction carried out in a school or college laboratory?

..................................................................................................................................

..................................................................................................................................[3]

[Total: 10]



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5 Isomerism occurs in many organic compounds. The two main forms of isomerism are structural isomerism and stereoisomerism. Many organic compounds that occur naturally have molecules that can show stereoisomerism, that is cis-trans or optical isomerism.

(a) (i) Explain what is meant by structural isomerism.

..................................................................................................................................

..................................................................................................................................

(ii) State two different features of molecules that can give rise to stereoisomerism.

..................................................................................................................................

..................................................................................................................................[3]

Unripe fruit often contains polycarboxylic acids, that is acids with more than one carboxylic acid group in their molecule.

One of these acids is commonly known as tartaric acid, HO2CCH(OH)CH(OH)CO2H.

(b) Give the structural formula of the organic compound produced when tartaric acid is reacted with an excess of NaHCO3.

[1]

Another acid present in unripe fruit is citric acid,

HO2CCH2CCH2CO2H

CO2H

OH

(c) Does citric acid show optical isomerism? Explain your answer.

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [1]



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A third polycarboxylic acid present in unripe fruit is a colourless crystalline solid, W, which has the following composition by mass: C, 35.8%; H, 4.5%; O, 59.7%.

(d) (i) Show by calculation that the empirical formula of W is C4H6O5.

(ii) The Mr of W is 134. Use this value to determine the molecular formula of W.

[3]

A sample of W of mass 1.97 g was dissolved in water and the resulting solution titrated with 1.00 mol dm–3 NaOH. 29.4 cm3 were required for complete neutralisation.

(e) (i) Use these data to deduce the number of carboxylic acid groups present in one molecule of W.

(ii) Suggest the displayed formula of W.

[5]

[Total: 13]



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This document consists of 12 printed pages.

DC (LEO/KN) 21252/2© UCLES 2010 [Turn over

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONSGeneral Certificate of EducationAdvanced Subsidiary Level and Advanced Level





*3828945530*

CHEMISTRY 9701/22


1 hour 15 minutes




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1 In the 19th and 20th centuries, experimental results showed scientists that atoms consist of a positive, heavy nucleus which is surrounded by electrons.

Then in the 20th century, theoretical scientists explained how electrons are arranged in

orbitals around atoms.

(a) The diagram below represents the energy levels of the orbitals present in atoms of the second period (Li to Ne).

(i) Label the energy levels to indicate the principal quantum number and the type of orbital at each energy level.

ener

gy

(ii) On the axes below, draw a sketch diagram of one of each different type (shape) of orbital that is occupied by the electrons in a second-period element.

Label each type.

zy

x

zy

x

2



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(iii) Complete the electronic configurations of nitrogen atoms and oxygen atoms on the energy level diagrams below.

Use arrows to represent electrons.

ener

gyen

ergy

nitrogen

oxygen [6]

(b) (i) Use the Data Booklet to state the value of the first ionisation energy of nitrogen and of oxygen.

N ............................... kJ mol–1 O ............................... kJ mol–1

(ii) Explain, with reference to your answer to (a)(iii), the relative values of these two ionisation energies.

..................................................................................................................................

..................................................................................................................................

.................................................................................................................................. [3]

[Total: 9]



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2 Copper, proton number 29, and argon, proton number 18, are elements which have different physical and chemical properties.

In the solid state, each element has the same face-centred cubic crystal structure which is shown below.

The particles present in such a crystal may be atoms, molecules, anions or cations. In the diagram above, the particles present are represented by .

(a) Which types of particle are present in the copper and argon crystals? In each case, give their formula.

element particle formula

copper

argon

[2]

At room temperature, copper is a solid while argon is a gas.

(b) Explain these observations in terms of the forces present in each solid structure.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [4]



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Although copper is a relatively unreactive element, when it is heated to a high temperature in an excess of chlorine, copper(II) chloride is formed.

When a mixture of argon and chlorine is heated to a high temperature, no reaction occurs.

(c) (i) How does chlorine behave in its reaction with copper?

..................................................................................................................................

(ii) Suggest a reason for the lack of a reaction between argon and chlorine.

..................................................................................................................................

.................................................................................................................................. [2]

The melting points of the noble gases neon to xenon are given below.

Ne Ar Kr Xe

melting poi nt /K 25 84 116 161

(d) Explain why there is an increase in melting point from neon to xenon.

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [2]

[Total: 10]



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3 The table below gives data for some of the oxides of Period 3 elements.

oxide Na2O MgO Al 2O3 SiO2 P4O6 SO2

melting poi nt /°C 1275 2827 2017 1607 24 –75

bonding

structure

(a) Complete the table by filling in

(i) the ‘bonding’ row by using only the words ‘ionic’ or ‘covalent’,

(ii) the ‘structure’ row by using only the words ‘simple’ or ‘giant’. [2]

(b) From the table of oxides above, suggest the formula of one oxide that is completely insoluble in water.

................... [1]

(c) Separate samples of Na2O and SO2 were added to water.

(i) For each oxide, write a balanced equation for its reaction with water and suggest a numerical value for the pH of the resulting solution.

Na2O

equation ...................................................................................................................

pH ............

SO2

equation ...................................................................................................................

pH ............

(ii) Construct a balanced equation for the reaction that occurs when a solution of Na2O in water reacts with a solution of SO2 in water.

.................................................................................................................................. [5]



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(d) Separate samples of the oxides MgO and SiO2 are melted. Each molten sample is then tested to see whether or not it conducts electricity.

Suggest what would be the results in each case. Explain your answers.

MgO .................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

SiO2 .................................................................................................................................

..........................................................................................................................................

.......................................................................................................................................... [4]

[Total: 12]



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4 An organic compound, E, has the following composition by mass: C, 48.7%; H, 8.1%; O, 43.2%.

(a) Calculate the empirical formula of E.

[2]

(b) When vaporised in a suitable apparatus, 0.130 g of E occupied a volume of 58.0 cm3 at 127 °C and 1.00 × 105 N m–2.

(i) Use the expression pV = mRTMr

to calculate Mr of E,

where m is the mass of E.

(ii) Hence calculate the molecular formula of E.

[4]

(c) Compound F, is an ester with the molecular formula C4H8O2.

F is one of four isomers, S, T, U, and V, that are all esters.

In the boxes below, the structural formula of S is given.

Draw the structural formulae of the other three isomers of F that are esters.

HCO2CH(CH3)2

S T U V

[3]



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(d) When the ester F is hydrolysed, an alcohol G is produced.

(i) What reagent can be used to hydrolyse an ester to an alcohol? ...................................

(ii) What other type of organic compound is produced at the same time?

................................... [2]

(e) On mild oxidation, the alcohol G gives a compound H which forms a silver mirror with Tollens’ reagent.

(i) What functional group does the reaction with Tollens’ reagent show to be present in compound H? Give the name of this group.

...................................

(ii) What type of alcohol is G?

.........................................

(iii) What could be the structural formula of the alcohol G?

[3]

(f) (i) Which of the four isomers, S, T, U, or V, could not be F?

.........................................

(ii) Explain your answer.

..................................................................................................................................

.................................................................................................................................. [2]

[Total: 16]



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5 Alkenes such as propene can be readily prepared from alcohols in a school or college laboratory by using the apparatus below.

mineral woolsoaked withthe alcohol

strong heat

Xpropene

water

(a) (i) Give the name of an alcohol that can be used in this apparatus to prepare propene.

.......................................................

(ii) Draw the skeletal formula of the alcohol you have named in (i).

(iii) What type of reaction occurs in this case?

....................................................... [3]

(b) (i) During the reaction, the material X becomes black in colour. Suggest the identity of the black substance and suggest how it is produced during

the reaction.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................



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(ii) At the end of the experiment, when no more propene is being produced, the delivery tube is removed from the water before the apparatus is allowed to cool.

Suggest why this done.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(iii) The material labelled X can be broken crockery, broken brick or pumice.

Give the chemical formula of a compound that is present in one of these materials.

..............................

(iv) State another reagent that could be used to produce propene from an alcohol.

....................................................... [5]

(c) Give the structural formula of the organic product formed when propene reacts separately with each of the following substances.

(i) bromine

(ii) cold, dilute manganate(VII) ions

(iii) hot, concentrated manganate(VII) ions

[3]



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(d) Propene may be polymerised.

(i) What is the essential condition for such a polymerisation?

.......................................................

(ii) The disposal of waste poly(propene) is very difficult. Give one important reason for this.

..................................................................................................................................

.................................................................................................................................. [2]

[Total: 13]






DC (LEO) 21255/1© UCLES 2010 [Turn over

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONSGeneral Certificate of EducationAdvanced Subsidiary Level and Advanced Level





*7524377035*

CHEMISTRY 9701/23


1 hour 15 minutes




1

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1 Hydrazine, N2H4, can be used as a rocket fuel and is stored as a liquid. It reacts exothermically with oxygen to give only gaseous products.

The enthalpy change of a reaction such as that between hydrazine and oxygen may be calculated by using standard enthalpy changes of formation.

(a) Define the term standard enthalpy change of formation, ΔHf .

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [3]

(b) Hydrazine reacts with oxygen according to the following equation.

N2H4(l) + O2(g) N2(g) + 2H2O(g)

(i) Use the data in the table to calculate the standard enthalpy change of this reaction.

compound ΔHf /kJ mol–1

N2H4(l) 50.6

H2O(g) –241.8

ΔH = ........................................ kJ mol–1

(ii) Although the above reaction is highly exothermic, hydrazine does not burn spontaneously in oxygen.


..................................................................................................................................

..................................................................................................................................



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(iii) Suggest why using hydrazine as a rocket fuel could be regarded as being ‘environmentally friendly’.

..................................................................................................................................

.................................................................................................................................. [4]

(c) The bonding in hydrazine is similar to that in ammonia.

(i) Showing outer-shell electrons only, draw a ‘dot-and-cross’ diagram of an ammonia molecule.

(ii) Draw a diagram to show the three-dimensional shape of an ammonia molecule.

(iii) Draw a diagram to show the shape of a hydrazine molecule. Show clearly which atom is joined to which and show clearly the value of one bond

angle.

[4]

(d) Deduce the oxidation state of nitrogen in hydrazine.

.......................................... [1]

[Total: 12]



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2 The alkali metals are a series of six elements in Group I of the Periodic Table. The first ionisation energy of these elements shows a marked trend as the Group is descended.

(a) Define the term first ionisation energy.

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [2]

(b) (i) State and explain the trend in first ionisation energy as Group I is descended.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Suggest how this trend helps to explain the increase in the reactivity of the elements as the Group is descended.

..................................................................................................................................

.................................................................................................................................. [3]

(c) In a redox reaction, 0.83 g of lithium reacted with water to form 0.50 dm3 of aqueous lithium hydroxide.

2Li(s) + 2H2O(l) 2LiOH(aq) + H2(g)

(i) Calculate the amount, in moles, of lithium that reacted.



5


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(ii) Calculate the volume of hydrogen produced at room temperature and pressure.

(iii) Calculate the concentration, in mol dm–3, of the LiOH(aq) formed.

[5]

(d) When heated in chlorine, all of the alkali metals react to form the corresponding chloride.

Describe what you see when sodium is heated in chlorine and write a balanced equation for the reaction.

description

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

equation

.......................................................................................................................................... [2]

[Total: 12]



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3 This question refers to the elements shown in the section of the Periodic Table below.

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

(a) From this list of elements, identify in each case one element that has the property described. Give the symbol of the element.

(i) an element that sinks in cold water and reacts readily with it

.............

(ii) an element that forms an oxide that is a reducing agent

.............

(iii) the element that has the largest first ionisation energy

.............

(iv) the metal in Period 3 (Na to Ar) that has the smallest cation

.............

(v) the element which has a giant molecular structure and forms an oxide which also has a giant molecular structure

.............

(vi) the element in Period 3 (Na to Ar) with the greatest electrical conductivity

............. [6]

(b) From the section of the Periodic Table above, identify two elements whose hydrides form hydrogen bonds between their molecules.

............. and ............. [1]



7


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(c) Use the elements in Period 3 (Na to Ar) in the section of the Periodic Table opposite to identify the oxide(s) referred to below.

In each case, give the formula of the oxide(s).

(i) an oxide which has no reaction with water

.............

. (ii) two acidic oxides formed by the same element

............. and .............

(iii) an oxide which dissolves readily in water to give a strongly alkaline solution

.............

(iv) an oxide which is amphoteric

............. [5]

[Total: 12]



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4 Organic reactions involve substances which may be

atoms, molecules, ions or free radicals.

We also apply the terms

electrophilic, nucleophilic, addition, elimination and substitution

to organic reactions.

Consider the following reactions.

CH4 + Cl 2 CH3Cl + HCl reaction 1

CH3CH2OH CH2=CH2 + H2O reaction 2

CH3I + OH– CH3OH + I – reaction 3

CH3COCH3 + HCN CH3C(OH)(CN)CH3 reaction 4

(a) Using the terms mentioned above, state as clearly as you can the nature of each of the following reactions.

reaction 1 .......................................................................

reaction 2 ....................................................................... [2]

(b) By considering the four reactions above, suggest a formula for each of the following substances.

In each case, state which reaction you are considering.

(i) one substance that is an addition product

reaction....... addition product

(ii) one substance that is a leaving group

reaction....... leaving group

(iii) one substance that behaves as an electrophile

reaction....... electrophile

[3]



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(c) What is meant by the term nucleophile?

..........................................................................................................................................

.................................................................................................................................... [1]

(d) Reactions 3 and 4 involve nucleophiles. For each reaction, give the formula of the nucleophile.

reaction 3

reaction 4

[2] (e) One characteristic reaction of ethene is its ability to decolourise bromine.

CH2=CH2 + Br2 BrCH2CH2Br

In this reaction, ethene behaves as a nucleophile.

Suggest an explanation for how ethene can behave in this way.

..........................................................................................................................................

.................................................................................................................................... [1]

[Total: 9]



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5 Lactic acid, 2-hydroxypropanoic acid, CH3CH(OH)CO2H, occurs naturally in sour milk and in our muscles when we take hard exercise.

Lactic acid is chiral and shows stereoisomerism.

(a) Draw fully displayed structures of the two optical isomers of lactic acid. Indicate with an asterisk (*) the chiral carbon atom in the lactic acid molecule.

[3]

(b) Lactic acid may be synthesised from ethanol by the following route.

CH3CH2OH step 1

CH3CHO step 2

CH3CH(OH)CN step 3

CH3CH(OH)CO2H

Give the reagent(s) and essential condition(s) for each step.

reagent(s) condition(s)

step 1

step 2

step 3

[6]



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During exercise, lactic acid is produced in our muscles from pyruvic acid, CH3COCO2H. This reaction occurs in the presence of the enzyme lactic acid dehydrogenase.

(c) (i) What type of chemical compound is the enzyme lactic acid dehydrogenase?

.................................................

(ii) How would you detect a small quantity of pyruvic acid in a sample of lactic acid?

State the reagent(s) you would use and what would be seen in your test.

reagent(s) .................................................................................................................

observation ...............................................................................................................

(iii) How would you detect a small quantity of lactic acid in a sample of pyruvic acid?

State the reagent(s) you would use and what would be seen in your test.

reagent(s) .................................................................................................................

observation ...............................................................................................................

(iv) What chemical reagent would be used to convert pyruvic acid into lactic acid?

CH3COCO2H CH3CH(OH)CO2H

................................................. [6]

[Total: 15]



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This question paper consists of 10 printed pages and 2 blank pages.

SP (SM/JB) S07971/7© CIE 2002 [Turn over

CAMBRIDGE INTERNATIONAL EXAMINATIONS

General Certificate of Education Advanced Subsidiary Leveland Advanced Level

CHEMISTRY 9701/2PAPER 2 OCTOBER/NOVEMBER SESSION 2002

1 hour

Candidates answer on the question paper.Additional materials:

Data Booklet

TIME 1 hour

INSTRUCTIONS TO CANDIDATES

Write your name, Centre number and candidate number in the spaces at the top of this page.

Answer all questions.

Write your answers in the spaces provided on the question paper.

INFORMATION FOR CANDIDATES

The number of marks is given in brackets [ ] at the end of each question or part question.

You may lose marks if you do not show your working or if you do not use appropriate units.

A Data Booklet is provided.

CandidateCentre Number Number

Candidate Name

FOR EXAMINER’S USE

1

2

3

4

5

6

TOTAL

UNIVERSITY of CAMBRIDGELocal Examinations Syndicate



2

9701/2/O/N/02

1 (a) Draw a diagram to show the Boltzmann distribution of molecular energies. Label the axes.

[2]

(b) Comment on the shape of the distribution curve.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[1]

(c) (i) Explain the meaning of the term activation energy.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) Insert and label the activation energy in your diagram in (a). [2]

(d) (i) Use a dotted line added to your diagram in (a) to show how the distribution ofmolecular energies changes at a slightly higher temperature (label this curve +δT ).

(ii) Use this new line to explain why reactions are faster at a higher temperature.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...............................................................................................................................[3]

[Total : 8]

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3

9701/2/O/N/02 [Turn over

2 Ethanoic acid is a common ingredient in cooking. It is also used in industry as a reagent.

(a) Ethanoic acid is a weak acid.

(i) Explain, in Bronsted-Lowry terms, what is meant by an acid.

...................................................................................................................................

...................................................................................................................................

(ii) Explain, with the aid of an equation, the term weak acid.

...................................................................................................................................

...................................................................................................................................[3]

(b) Ethanoic acid, CH3CO2H, reacts with ethanol, C2H5OH, to produce ethyl ethanoate andwater. The reaction is an example of dynamic equilibrium.


(i) Explain what is meant by dynamic equilibrium.

...................................................................................................................................

...................................................................................................................................

(ii) Write an expression for the equilibrium constant, Kc, for this reaction.

[2]

(c) A mixture of 6.0 g of ethanoic acid and 6.0 g of ethanol was added to 4.4 g of ethylethanoate and the overall mixture allowed to reach equilibrium. It was found that0.040 mol of ethanoic acid was present in the equilibrium mixture.

(i) Calculate the number of moles of each compound, both initially and at equilibrium.Place the results in the spaces provided.


initially .............. .............. .............. 0.00

at equilibrium 0.040 .............. .............. ..............

ForExaminer’s

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4

9701/2/O/N/02

(ii) Calculate the equilibrium constant, Kc, for the reaction.

(iii) Explain why Kc in this reaction has no units.

...............................................................................................................................[4]

[Total : 9]

3 The oxides of the third period include the following:

Na2O; MgO; Al2O3; SO2; SO3.

(a) Showing outer electrons only, draw a dot-and-cross electron diagram for magnesiumoxide, MgO.

[1]

(b) From the list above, identify one oxide (in each case) which fits the description given.

(i) An oxide that reacts with water forming a strongly alkaline solution.

..........................................................

(ii) An oxide that is insoluble in water.

..........................................................

(iii) An oxide that reacts vigorously with water forming a strongly acidic solution.

..........................................................

(iv) An oxide that has a simple molecular structure.

..........................................................

(v) An oxide that acts as a food preservative.

..........................................................[5]

ForExaminer’s

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5


(c) Write equations for the reaction of

(i) aluminium oxide and dilute hydrochloric acid,

...................................................................................................................................

(ii) sulphur dioxide and aqueous sodium hydroxide.

...................................................................................................................................[2]

(d) Antimony, Sb, has been known for about 6000 years. It is present in many ancient formsof bronze, but now its main use is to strengthen lead alloys.

Antimony is produced in a two-stage process from stibnite, a sulphide ore, Sb2S3.

The ore is first roasted in oxygen to form the oxide.

2Sb2S3 + .............. O2 → Sb4O6 + ..............SO2

(i) Balance the above equation.

The oxide is then reduced with carbon.

Sb4O6 + 3C → 4Sb + 3CO2

(ii) What is the oxidation number of antimony in Sb4O6?

..........................................................

(iii) Calculate the volume of carbon dioxide, measured at room temperature andpressure, that would be produced by the processing of 10 moles of Sb2S3.

[4]

[Total : 12]

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9701/2/O/N/02

4 Ammonia is manufactured from nitrogen and hydrogen by the Haber process.

Hydrogen is usually obtained by reacting methane and steam; the by-product is carbonmonoxide.

(a) Construct a balanced equation for this production of hydrogen.

......................................................................................................................................[1]

The reaction between nitrogen and hydrogen is exothermic and incomplete.

(b) (i) Write an equation for the Haber process.

...................................................................................................................................

(ii) State the three conditions necessary for the efficient working of a Haber processplant.

1. ..............................................................................................................................

2. ..............................................................................................................................

3. ..............................................................................................................................

(iii) Draw a flow diagram to show how the gases pass through the plant. The partwhere the ammonia is formed should be called the converter. Label the flowdiagram to explain the process.

[6]

(c) Explain why the pressure you have quoted in (b)(ii) is used.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

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7


(d) Most of the ammonia produced which is not used as fertiliser, is oxidised to nitric acid,HNO3.

Construct an equation for the oxidation of ammonia by atmospheric oxygen to formnitric acid.

......................................................................................................................................[1]

(e) Urea, CO(NH2)2, is a naturally occurring substance which can be hydrolysed with waterto form ammonia according to the following equation.

H2O(l) + CO(NH2)2(aq) → CO2(aq) + 2NH3(aq)

The standard enthalpy changes of formation of water, urea, carbon dioxide and ammonia(in aqueous solution) are given below.

Use these data to calculate the standard enthalpy change for the hydrolysis of urea.

[2]

[Total : 12]

ForExaminer’s

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compound

H2O(l)

CO(NH2)2(aq)

CO2(aq)

NH3(aq)

∆H f /kJ mol–1

–287.0

–320.5

–414.5

–81.0

�



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9701/2/O/N/02

5 Samples of the following compounds were labelled A to E as shown.

A CH3CH2CH2OH

B CH3CH2CH(OH)CH3

C CH3CHO

D CH3COCH3

E CH3CH=CHCH3

Complete the table below by inserting the letter (or letters) of the compounds that correspondto each test.

[9]

[Total : 9]

ForExaminer’s

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reagent

acidified potassiumdichromate(VI)

acidified potassiummanganate(VII)

hydrogen in the presenceof a platinum catalyst

Fehling’s reagent

2,4-dinitrophenylhydrazine

bromine in an inertsolvent

observation

green colour obtainedon boiling

ethanoic acid obtainedon boiling

hydrogen absorbed

brown-red precipitateobtained on boiling

orange precipitate

solution decolourised

letter(s)



9


6 Pentan-1-ol, C5H11OH, is important in the synthesis of organic compounds.

(a) Give the structural formula of another primary alcohol which is an isomer of pentan-1-ol.

[1]

(b) (i) Write a balanced equation for the preparation of 1-bromopentane from pentan-1-ol.

(ii) This preparation gives a yield of 60%. Calculate the mass of pentan-1-ol requiredto produce 15.0 g of 1-bromopentane.

[3]

(c) Dehydration of pentan-1-ol produces pent-1-ene. Sketch on the diagram below theorbital overlap between the two carbon atoms. Label the bonds.

[2]

C C

H H

H C3H7

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10

9701/2/O/N/02

(d) The two compounds below are among many secreted by insects to attract members ofthe same species. Such compounds are used in traps to control insect populations.They need to be made synthetically.

For each synthesis outline how they could be prepared from pentan-1-ol, giving thenecessary reagents and conditions.

(i) CH3(CH2)3CO2H

(ii) CH3CO2(CH2)4CH3

[4]

[Total : 10]

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SP (SC) S30315/4© CIE 2003 [Turn over



CHEMISTRY 9701/02

Paper 2 Structured Questions AS CoreOctober/November 2003

1 hourCandidates answer on the Question Paper.Additional Materials:

Data Booklet


Write your name, Centre number and candidate number in the spaces provided at the top of this page.Write in dark blue or black pen in the spaces provided on the Question Paper.You may use a pencil for any diagrams, graphs or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.

Answer all questions.The number of marks is given in brackets [ ] at the end of each question or part question.You may lose marks if you do not show your working or if you do not use apropriate units.






2

9701/02/O/N/03

1 (a) Salt, sodium chloride, forms transparent colourless crystals. Describe the bonding insodium chloride crystals, give the formula of each particle and sketch part of the crystalstructure.

[3]

(b) Explain why crystals of sodium chloride do not conduct electricity, but molten sodiumchloride does.

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

(c) (i) With the aid of a diagram of the cell, outline the manufacture of chlorine from brine(aqueous sodium chloride).

(ii) Write the electrode equations, including state symbols.

anode ........................................................................................................................

cathode .....................................................................................................................

ForExaminer’s

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3


(iii) Name the two by-products of this electrolysis, and give one commercial use ofeach.

by-product I ...............................................................................................................

use ............................................................................................................................

by-product II ..............................................................................................................

use ............................................................................................................................

(iv) Explain, with the aid of an equation, why the chlorine generated from the cell has tobe kept away from the liquid in the cathode compartment.

...................................................................................................................................

...................................................................................................................................

...............................................................................................................................[9]

[Total : 14]

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9701/02/O/N/03

2 A car can be considered to run on octane, C8H18.

(a) Write an equation for the complete combustion of octane.

......................................................................................................................................[1]

The composition of the exhaust gases (fumes) from a petrol (gasoline) engine is givenbelow.

(b) (i) What gas, omitted from the table, makes up most of the remainder of the exhaustfumes?

...................................................................................................................................

(ii) Explain why there is always water vapour in the exhaust fumes.

...................................................................................................................................[2]

(c) (i) State two gases in the exhaust fumes which are poisonous to humans. Also statebriefly for each the particular effect on humans.

gas I ..........................................................................................................................

effect .........................................................................................................................

gas II .........................................................................................................................

effect .........................................................................................................................

(ii) The two gases you have given in (c)(i) can be removed by reaction in a platinisedcatalytic converter. The products of the reaction in the converter are not hazardous.For each of your gases in (c)(i) give an equation which shows how it is removed toform less harmful substances.

I .................................................................................................................................

II ................................................................................................................................

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PercentageGas by volume

carbon dioxide 9water vapour 8oxygen 4hydrogen 2carbon monoxide 3–6hydrocarbons 0.2nitrogen oxides 0.4–0.05



5


(iii) Suggest one reason why the exhaust fumes from a car fitted with a catalyticconverter are still hazardous to human health to some degree.

...................................................................................................................................

...................................................................................................................................

...............................................................................................................................[5]

[Total : 8]

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9701/02/O/N/03

3 (a) (i) What is meant by the standard enthalpy change of formation, �H f, of a compound?Explain what is meant by the term standard.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) Write an equation, with state symbols, for the �H f of water.

...................................................................................................................................

(iii) Explain why the �H f for water is identical to the standard enthalpy change ofcombustion of hydrogen.

...................................................................................................................................

...............................................................................................................................[4]

(b) When calcium is placed in water, aqueous calcium hydroxide is formed and hydrogen isgiven off.

(i) Write the equation for the reaction of calcium with water.

...................................................................................................................................

(ii) When 1.00 g of calcium is placed in 200 g of water, the temperature increases by12.2 °C when the reaction is completed. The specific heat capacity of water, c, is4.2 J g–1 K–1.

Calculate the heat released in the experiment.

ForExaminer’s

Useo_

o_

o_



7


(iii) Calculate the standard enthalpy change of reaction in k J mol–1 for your equation in(b)(i).

[4]

(c) (i) State Hess’ Law.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) Use Hess’ Law and your result in (b)(iii) to calculate the �H f of Ca(OH)2 (aq). Youalso need the �H f of water which is –286 k J mol–1.

[4]

(d) Calculate the volume of hydrogen, measured at room temperature and pressure,liberated in the experiment described in (b)(ii).

[2]

[Total : 14]

ForExaminer’s

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o_

o_



8

9701/02/O/N/03

4 The apparatus shown can be used to prepare ethene from ethanol.

(a) (i) State what type of reaction takes place on the hot pumice.

...................................................................................................................................

(ii) Write an equation for this preparation.

...................................................................................................................................[2]

(b) Describe the colour changes which are observed and write equations for the reaction ofethene with the following two reagents.

(i) bromine

colour change from ..................................... to ........................................................

equation ....................................................................................................................

(ii) cold, dilute, acidified manganate(VII) ions

colour change from ..................................... to ........................................................

equation ....................................................................................................................[4]

water

mineral wooland ethanol

pumice

strongheat

ethene

ForExaminer’s

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9


(c) Draw structures for each of the following polymers showing two repeat units.

(i) poly(ethene)

(ii) pvc [poly(chloroethene)]

[2]

(d) The formula of the alkene cyclohexene can be written as shown.

(i) State the molecular formula of cyclohexene. ............................................................

(ii) Calculate the percentage of carbon by mass in cyclohexene.

[3]

[Total :11]

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9701/02/O/N/03

5

(a) 1-Bromobutane reacts with aqueous sodium hydroxide to form butan-1-ol.

(i) Give a balanced equation for this reaction.

...................................................................................................................................

(ii) Name the type of reaction. ........................................................................................

(iii) Describe the mechanism of this reaction.

[5]

(b) 1-Bromobutane and 2-bromo-2-methylpropane both react with an ethanolic (alcoholic)solution of sodium hydroxide to form alkenes.

(i) Name the type of reaction. ........................................................................................

(ii) Identify, by means of the structural formula, the alkene formed from

I 1-bromobutane,

II 2-bromo-2-methylpropane.

CH3CH2CH2CH2Br

1-bromobutane

CH3 C

CH3

CH3

2-bromo-2-methylpropane

Br

ForExaminer’s

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11

9701/02/O/N/03

(iii) Hot, concentrated manganate(VII) ions break the double bond in alkenes. Each ofthe two alkenes in (b)(ii) gives CO2 and H2O from the terminal group, but the restof the molecule remains as an organic oxidation product. Suggest the formula ofeach of these products.

from I .........................................................................................................................

from II ........................................................................................................................[5]

(c) Complete the reaction sequence giving the intermediate, the reagents and theconditions for the synthesis of 2,2-dimethylpropanoic acid.

Step I: reagent .............................................................................................................

conditions .........................................................................................................

Step II: reagent .............................................................................................................

conditions .........................................................................................................[3]

[Total : 13]

CH3 C

CH3

CH3

Br CH3 C

CH3

CH3

CO2Hstep

I

step

II

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9701/02/O/N/03

BLANK PAGE



This document consists of 11 printed pages and 1 blank page.SP (AT) S83011/2© UCLES 2004 [Turn over

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONSGeneral Certificate of Education – Advanced Subsidiary Level andAdvanced Level

CHEMISTRY

Paper 2 Structured Questions AS Core 9701/02October/November 2004

1 hour 15 minutesCandidates answer on the Question Paper.Additional Materials:

Data Booklet


Write your name, Centre number and candidate number in the spaces provided at the top of this page.Write in dark blue or black pen in the spaces provided on the Question Paper.You may use a pencil for any diagrams, graphs or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.

Answer all questions.The number of marks is given in brackets [ ] at the end of each question or part question.You may lose marks if you do not show your working or if you do not use appropriate units.




1

2

3

4

5

TOTAL

Candidate

Name

Centre

Number

Candidate

Number

If you have been given a label, look at thedetails. If any details are incorrect ormissing, please fill in your correct detailsin the space given on this page.




2

9701/02/O/N/04

1 Hydrogen iodide dissociates into its elements according to the equation below.

2HI(g) H2(g) + I2(g)

(a) Write the expression for the equilibrium constant, Kc.

[1]

(b) At 120 °C the equilibrium mixture contains 1.47 mol dm–3 of HI(g), 0.274 mol dm–3 eachof H2(g) and I2(g).

Calculate the value of Kc for the equilibrium at 120 °C.

[1]

(c) Suggest and explain why it would be more difficult to determine Kc for this equilibrium atroom temperature.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

(d) (i) Explain how enthalpy changes, ∆H values, for covalent bonded molecules can becalculated from bond energies.

...................................................................................................................................

...................................................................................................................................

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© UCLES 2004



3


(ii) Use bond energies from the Data Booklet to calculate ∆H for the followingdissociation.

2HI(g) → H2(g) + I2(g)

[3]

(e) HI dissolved in water behaves as a strong acid.

(i) Explain what is meant by a strong acid.

...................................................................................................................................

(ii) Complete the equation.

HI + H2O → .......... + ..........

(iii) Identify the conjugate base of HI in this equation.

...............................................................................................................................[3]

[Total : 10]

ForExaminer’s

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© UCLES 2004



4

9701/02/O/N/04

2 The table below gives data on some oxides of elements in Period 3 of the Periodic Table.

(a) Write an equation for the reaction of aluminium with oxygen to form aluminium oxide.

......................................................................................................................................[1]

(b) Drawing diagrams where appropriate, suggest in terms of structure and bonding,explanations for the following.

(i) the high melting point and boiling point of Al2O3

(ii) the low boiling point of SO3

(iii) the melting point of SiO2 is much higher than that of P4O10

[7]

ForExaminer’s

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© UCLES 2004

oxide Na2O MgO Al2O3 SiO2 P4O10 SO3

melting point / K 1193 3125 2345 1883 853 290

boiling point / K 1548 3873 3253 2503 – 318



5


(c) Water was added to each of the oxides in the table.

Choosing a suitable oxide in each case, write an equation for the formation of

(i) an alkaline solution, ..................................................................................................

(ii) an acidic solution. .................................................................................................[2]

[Total : 10]

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© UCLES 2004



6

9701/02/O/N/04

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© UCLES 2004

3 (a) (i) Describe, with the aid of a fully labelled diagram, the industrial electrolysis of brine(aqueous NaCl). State what the electrodes are made of and show clearly the inletand the outlets.

(ii) Write equations for the reactions at each electrode, giving state symbols.

anode ........................................................................................................................

cathode .....................................................................................................................

(iii) Explain in terms of changes in oxidation number why redox processes take place atthe electrodes.

anode ........................................................................................................................

cathode .....................................................................................................................

(iv) Name the chemical which is produced in solution by this electrolysis.

...................................................................................................................................

(v) Suggest two large scale uses of this chemical.

...................................................................................................................................

...................................................................................................................................[10]



7


(b) Hydrochloric acid is manufactured by burning the hydrogen formed in this electrolysis inchlorine and dissolving the product in water.

(i) Construct an equation for the burning of hydrogen in chlorine.

...................................................................................................................................

(ii) When the product of (i) dissolves in water there is a change in bonding. Explainwith the aid of an equation what change in bonding has occurred.

[2]

(c) Describe, with the aid of equations including state symbols, what happens when

(i) hydrochloric acid is added to aqueous silver nitrate,

...................................................................................................................................

...................................................................................................................................

(ii) an excess of aqueous ammonia is added to the resulting mixture.

...................................................................................................................................

...................................................................................................................................

...............................................................................................................................[5]

[Total : 17]

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© UCLES 2004



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9701/02/O/N/04

4 Some perfumes and scents of flowers and fruit contain compounds which are structuralisomers. Two such examples are citronellol and geraniol.

(a) Confirm that citronellol and geraniol are isomers by calculating their molecular formulaand their relative molecular mass, Mr.

(i) Molecular formula .....................................................................................................

(ii) Mr ..........................................................................................................................[2]

(b) Name two functional groups present in both molecules.

(i) .....................................................................................................................................

(ii) .................................................................................................................................[3]

Citronellol and geraniol also show stereo isomerism.

(c) On the diagram of the structure of citronellol above, draw a circle around a chiral carbonatom. [1]

H C

OH

H

C

H

H

C

C C

H

CH3

C

H

H

C

H

H

H CH3

CH3

citronellol

CH3 C

CH3

H

C

H

H

C

C C

H

H

C

H

H

CH3 CH2OH

H

geraniol

ForExaminer’s

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© UCLES 2004



9


(d) (i) Draw the other cis-trans isomer of geraniol. [In parts (d) and (f) use R – torepresent a part of the molecule.]

(ii) Explain why geraniol has no optical isomers.

...................................................................................................................................

...............................................................................................................................[2]

(e) State what you would expect to see if citronellol was reacted with aqueous bromine.

..........................................................................................................................................

......................................................................................................................................[1]

(f) Draw structures of the organic products when geraniol reacts with each of the followingreagents.

(i) an excess of H+ / Cr2O72– under reflux

(ii) ethanoic acid in the presence of an acidic catalyst

(iii) hydrogen bromide, HBr

[4]

[Total : 13]

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© UCLES 2004



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9701/02/O/N/04

5 2-Hydroxypropanoic acid (lactic acid), CH3CH(OH)CO2H, can be prepared in a two-stagesynthesis from ethanal, CH3CHO.

(a) In the first stage, ethanal reacts with hydrogen cyanide, HCN, in the presence of anNaCN catalyst to produce a cyanohydrin.

(i) Write an equation for the reaction of ethanal and HCN, giving the displayed formulaof the product.

(ii) State what type of reaction this is.

...................................................................................................................................

(iii) Describe the mechanism of this reaction.

[5]

(b) In the second stage, the product from (a) is converted into lactic acid.

(i) Write the equation for this stage.

...................................................................................................................................

(ii) State what type of reaction this is.

...............................................................................................................................[2]

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© UCLES 2004



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9701/02/O/N/04

(c) In this synthesis 4.40 g of ethanal were used and at the end 5.40 g of lactic acid wereobtained.

Calculate the percentage yield of lactic acid.

[3]

[Total : 10]

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© UCLES 2004



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9701/02/O/N/04

BLANK PAGE

University of Cambridge International Examinations is part of the University of Cambridge Local Examinations Syndicate (UCLES) which is itself a department ofthe University of Cambridge.



This document consists of 10 printed pages and 2 blank pages.SP (MML 8078 3/04) T02630/3© UCLES 2005 [Turn over

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education – Advanced Subsidiary Level andAdvanced Level

CHEMISTRY

Paper 2 Structured Questions AS Core 9701/02October/November 2005



Write your name, Centre number and candidate number in the spaces provided.Write in dark blue or black pen in the spaces provided on the Question Paper.You may use a pencil for any diagrams, graphs, or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.

Answer all questions.The number of marks is given in brackets [ ] at the end of each question or part question.You may lose marks if you do not show your working or if you do not use appropriate units.A Data Booklet is provided.You may use a calculator.



If you have been given a label, look at thedetails. If any details are incorrect ormissing, please fill in your correct detailsin the spaces provided.



4

3

2

1

5

TOTAL




1 The first six ionisation energies of an element X are given below.

(a) Define the term first ionisation energy.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [3]

(b) Write an equation, with state symbols, for the second ionisation energy of element X.

.................................................................................................................................... [2]

(c) Use the data given above to deduce in which Group of the Periodic Table element X isplaced. Explain your answer.

Group ...............................................................................................................................

explanation ......................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [3]

The first ionisation energies (I.E.) for the elements of Group IV are given below.

(d) Explain the trend shown by these values in terms of the atomic structure of the elements.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [4]

[Total: 12]

2

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9701/02/O/N/05© UCLES 2005

first second third fourth fifth sixth

ionisation energy / kJ mol–1

950 1800 2700 4800 6000 12300

element C Si Ge Sn Pb

1090 786 762 707 7161st I.E. / kJ mol–1



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3




2 Carbon disulphide, CS2, is a volatile, stinking liquid which is used to manufacture viscoserayon and cellophane.

(a) The carbon atom is in the centre of the CS2 molecule.

Draw a ‘dot-and-cross’ diagram of the carbon disulphide molecule.

Show outer electrons only.

[2]

(b) Suggest the shape of the molecule and give its bond angle.

shape .........................................................

bond angle ................................................. [2]

(c) Explain the term standard enthalpy change of formation, �H f .

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [3]

(d) Calculate the standard enthalpy change of formation of CS2 from the following data.

standard enthalpy change of formation of SO2 = –298 kJ mol–1

standard enthalpy change of formation of CO2 = –395 kJ mol–1

standard enthalpy change of combustion of CS2 = –1110 kJ mol–1

[3]

4

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9701/02/O/N/05© UCLES 2005



(e) Carbon disulphide reacts with nitrogen monoxide, NO, to form a yellow solid and twocolourless gases which are produced in a 1:1 molar ratio.

Deduce the identity of each gas and write a balanced equation for the reaction.

gases ........................................................ and ...............................................................

equation ..................................................................................................................... [3]

[Total: 13]

5

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3 Nitrogen, which makes up about 80% of the Earth’s atmosphere, is very unreactive.

(a) (i) Explain the lack of reactivity of nitrogen.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Nitrogen does, however, undergo some reactions. Write an equation for onereaction of nitrogen, stating the conditions under which it occurs.

equation ...................................................................................................................

conditions .................................................................................................................

..................................................................................................................................

..................................................................................................................................

(iii) Suggest why nitrogen does react in the example you have chosen.

..................................................................................................................................

..................................................................................................................................[6]

Ammonium nitrate, NH4NO3, is a commercially important compound of nitrogen.

(b) (i) State one large-scale use of ammonium nitrate.

..................................................................................................................................

(ii) What are the environmental consequences of the uncontrolled use of ammoniumnitrate?

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[4]

6

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When solid ammonium nitrate is heated with solid sodium hydroxide in a test-tube, threeproducts are formed. A colourless alkaline gas, Y, is given off, and a colourless liquid canbe seen on the cooler parts of the test-tube. A white solid remains in the tube.

(c) (i) Identify gas Y.

..................................................................................................................................

(ii) Write an equation, with state symbols, for the reaction of ammonium nitrate withsodium hydroxide.

..................................................................................................................................[3]

(d) In order to produce gas Y in a pure state in the laboratory, it must be passed through adrying agent.

Why is concentrated sulphuric acid not suitable for drying gas Y?

..........................................................................................................................................

.................................................................................................................................... [1]

[Total: 14]

7

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9701/02/O/N/05© UCLES 2005



4 Alcohols are widely used as solvents and in the manufacture of esters.

Butan-1-ol, C4H10O, is an example of a primary alcohol.

(a) What is meant by the term primary alcohol?

.................................................................................................................................... [1]

(b) There are three more alcohols with molecular formula C4H10O that are structuralisomers of butan-1-ol.

Complete the table below by drawing displayed formulae of each of these threecompounds.

For each isomer, state whether it is a primary, secondary, or tertiary alcohol.

[6]

8

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9701/02/O/N/05© UCLES 2005

H

H

H

C C

H

H

C

H

H

C OH

H

H

primary

butan-1-ol isomer 2 isomer 3 isomer 4



(c) Butan-1-ol can be oxidised to a carboxylic acid by heating with an acidified solution ofpotassium dichromate(VI).

(i) What colour change would be seen during this reaction?

from ....................................................... to .............................................................

(ii) State which of the isomers you have drawn in (b) could also be oxidised to form acarboxylic acid.

..................................................................................................................................[3]

[Total: 10]

9

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9701/02/O/N/05© UCLES 2005



5 Compound Z, an organic compound with three functional groups, has the molecularformula C4H6O2. The functional groups can be confirmed by the following tests.

(a) Test for the first functional group.

Z decolourises aqueous bromine.

What functional group is shown to be present in Z by this test?

.................................................................................................................................... [1]

(b) Tests for the second functional group.

Z reacts with sodium to give hydrogen and a solid compound of formula C4H5O2Na.

When Z is heated with ethanoic acid and a few drops of concentrated sulphuric acid, asweet smelling liquid of molecular formula C6H8O3 is formed.

What functional group is shown to be present in Z by these tests?

.................................................................................................................................... [1]

(c) Tests for the third functional group.

A few drops of Z form a yellow/orange precipitate when added to 2,4-dinitrophenylhydrazine reagent.

When a few drops of Z are warmed with Tollens’ reagent, a silver mirror is formed.

What functional group is shown to be present in Z by these tests?

.................................................................................................................................... [1]

(d) Z does not show cis-trans isomerism.

Draw the displayed formula of Z.

[2]

10

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9701/02/O/N/05© UCLES 2005



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9701/02/O/N/05© UCLES 2005

In parts (e) and (f) you may use R– to represent the part of the molecule that does notreact.

(e) What is the organic compound formed by the reactions of Z in each of the tests in (b)?

with sodium

with ethanoic acid

[2]

(f) Draw the structure of the organic compound formed by Z in each of the tests in (c).

with Tollens’ reagent

with 2,4-dinitrophenylhydrazine,

[2]

(g) But-2-enoic acid is an isomer of Z which shows cis-trans isomerism.

Draw a displayed formula of the cis isomer of this acid.

[2]

[Total: 11]

NHNH2

NO2

NO2

11



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12

9701/02/O/N/05

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University of Cambridge International Examinations is part of the University of Cambridge Local Examinations Syndicate (UCLES), which is itself a departmentof the University of Cambridge.




SP (SC/MML) T27660/4© UCLES 2006 [Turn over

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONSGeneral Certificate of Education


CHEMISTRY


9701/02

October/November 2006



Write your Centre number, candidate number and name on all work you hand in.Write in dark blue or black pen.You may use a pencil for any diagrams, graphs, or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.



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1 In the 19th and 20th centuries, scientists established the atomic theory and showed that three sub-atomic particles, electron, neutron and proton, exist. The masses and charges of these three particles were subsequently determined.

When separate beams of electrons, neutrons or protons are passed through an electric field in the apparatus below, they behave differently.

+ –

beam of particles

(a) (i) Which of these three particles will be deflected the most by the electric field?

.........................................

(ii) In which direction will this particle be deflected?

..................................................................................................................................

(iii) Explain your answer.

..................................................................................................................................

..................................................................................................................................[4]

(b) (i) Define the term proton number.

..................................................................................................................................

..................................................................................................................................

(ii) Why is the proton number of an atom of an element usually different from the nucleon number of an atom of the element?

..................................................................................................................................

..................................................................................................................................[2]



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(c) Protons and neutrons have been used in nuclear reactions which result in the formation of artificial elements. In such processes, protons or neutrons are accelerated to high speeds and then fired like ‘bullets’ at the nucleus of an atom of an element.

Suggest why neutrons are more effective than protons as ‘nuclear bullets’.

..........................................................................................................................................

..................................................................................................................................... [2]

(d) In some cases, when neutrons are fired at atoms of an element, the neutrons become part of the nucleus of those atoms.

What effect does the presence of an extra neutron have on the chemical properties of the new atoms formed? Explain your answer.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

[Total: 10]



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2 Copper and iodine are both solids which have different physical and chemical properties. Each element has the same face-centred crystal structure which is shown below.

The particles present in such a crystal may be atoms, molecules, anions or cations. In the diagram above, the particles present are represented by .

(a) Which type of particles are present in the iodine crystal? Give their formula.

particle ....................................

formula .................................... [2]

(b) When separate samples of copper or iodine are heated to 50 °C, the copper remains as a solid while the iodine turns into a vapour.

(i) Explain, in terms of the forces present in the solid structure, why copper remains a solid at 50 °C.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Explain, in terms of the forces present in the solid structure, why iodine turns into a vapour when heated to 50°C.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[4]



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(c) (i) Although copper is a relatively unreactive metal, when it is heated to a high temperature in an excess of chlorine, copper(II) chloride is formed.

How does chlorine behave in this reaction?

..................................................................................................................................

(ii) When a mixture of copper and iodine is heated to a high temperature, no reaction occurs.

Suggest a reason for this difference.

..................................................................................................................................

..................................................................................................................................[2]

[Total: 8]



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3 This question refers to the elements shown in the Periodic Table below.

H HeLi Be B C N O F NeNa Mg Al Si P S Cl ArK Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

(a) From the elements shown, identify in each case one element that has the property described. Give the name or formula of the element.

(i) An element that has a molecule which contains only one atom.

...................................................

(ii) An element that has a molecule which contains only four atoms.

...................................................

(iii) The element that has the largest atomic radius.

...................................................

(iv) The element that is a liquid at room temperature and pressure.

...................................................

(v) The element in Period 3 (Na to Ar) that has the highest melting point.

...................................................

(vi) The element in Period 3 (Na to Ar) that forms the largest anion.

...................................................

[6]



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(b) Use the elements shown opposite to answer the following questions.

(i) Give the formulae of two acidic oxides formed by the same element.

............................. and ...............................

(ii) Give the name or formula of an oxide that is amphoteric.

...................................................

(iii) Identify an element whose oxide dissolves readily in water to give a strongly alkaline solution.

...................................................

(iv) Identify an element in Period 3 (Na to Ar) whose chloride dissolves in water to give a neutral solution.

...................................................

(v) Identify an element that reacts with water to give a solution that can behave as an oxidising agent.

...................................................

[6]

[Total: 12]



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4 Octadecane, C18H38, is a long chain hydrocarbon which is present in crude oil. Such long chain hydrocarbons are ‘cracked’ to produce alkanes and alkenes which have smaller molecules.

(a) Give two different conditions under which long chain molecules may be cracked.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

(b) Octadecane, C18H38, can be cracked to form hexane and an alkene.

Write a balanced equation for this reaction.

..................................................................................................................................... [1]

Alkenes are important industrially because the C=C bond makes them very reactive.

(c) Ethene reacts with bromine to give 1,2-dibromoethane.

(i) What type of reaction is this?

..................................................................................................................................

(ii) Outline the mechanism of this reaction, giving the structure of the intermediate.

Show clearly any relevant dipoles, charges and lone pairs of electrons.

=C CH

H

H

H

C CH

H

H

HBr Br

Br Br

[4]



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The unsaturated hydrocarbon Z is obtained by cracking hexane and is important in the chemical industry.

The standard enthalpy change of combustion of Z is –2059 kJ mol–1.

(d) Define the term standard enthalpy change of combustion.

..........................................................................................................................................

..................................................................................................................................... [2]

When 0.47 g of Z were completely burnt in air, the heat produced raised the temperature of 200 g of water by 27.5 °C.

(e) (i) Calculate the amount of heat released in this experiment.

(ii) Use the data above and your answer to (i) to calculate the relative molecular mass of Z.

[4]

(f) Deduce the molecular formula of Z.

[1]

(g) The unsaturated hydrocarbon Z can be polymerised.

Draw the structure of the polymer of Z showing two repeat units.

[1]

[Total: 15]



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5 Lactic acid, 2-hydroxypropanoic acid, CH3CH(OH)CO2H, occurs in sour milk.

Glycollic acid, 2-hydroxyethanoic acid, HOCH2CO2H, occurs in sugar cane.

(a) Lactic acid may be synthesised from propene by the following sequence.

step I step II CH3CH=CH2 CH3CH(OH)CH2OH CH3CH(OH)CO2H

(i) What reagent(s) and condition(s) are used for step I?

reagent(s) .................................................................................................................

condition(s) ...............................................................................................................

(ii) What type of reaction is step II? ..................................................................................................................................

[3]

(b) Glycollic acid may be synthesised from ethanoic acid by the following sequence.

step III step IV CH3CO2H ClCH2CO2H HOCH2CO2H

(i) Suggest the reagent(s) and condition(s) that are used for step III.

reagent(s) .................................................................................................................

condition(s) ...............................................................................................................

(ii) What reagents and conditions are used in step IV?

reagent(s) .................................................................................................................

condition(s) ...............................................................................................................[4]

(c) Lactic acid and glycollic acid react differently when heated under reflux with acidified dichromate(VI) ions.

Draw the structural formula of the organic product in each case.

product from lactic acid product from glycollic acid

[2]



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(d) Lactic acid is chiral. Draw displayed formulae of the two optical isomers of lactic acid clearly showing their three-dimensional structures. Indicate with an asterisk (*) the chiral carbon atom in each.

[2]

Glycollic acid and lactic acid each give the reactions of an alcohol group and of a carboxylic acid group. Each compound will react with the other to give an ester.

(e) When one molecule of glycollic acid reacts with one molecule of lactic acid, it is possible to form two different esters.

Draw the structure of each of these esters.

[2]

Glycollic acid and lactic acid are reacted together to make the material for ‘soluble stitches’ (also known as ‘soluble sutures’) which are used in surgery.

In this material, many molecules of each acid have been reacted to form a long chain ‘polyester’ molecule which contains many ester groups.

This polyester is used in surgery to sew up wounds inside the body.

Over a period of time, the polyester undergoes a chemical reaction and breaks up to re-form the two individual hydroxy-acids.

(f) (i) This reaction occurs where the pH of the body is about pH5 to pH6. Suggest what type of chemical reaction causes the polyester material to break up.

..................................................................................................................................

(ii) Suggest why the products of this reaction are soluble in water.

..................................................................................................................................

..................................................................................................................................[2]

[Total: 15]



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University of Cambridge International Examinations is part of the University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.




SP (SJF4554) T71255/1© UCLES 2008 [Turn over






*2045742995*

CHEMISTRY 9701/02

Paper 2 Structured Questions AS Core October/November 2008

1 hour 15 minutes




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1 Most submarines travel under water using electrical power from batteries. The German engineer Helmut Walter designed a diesel engine that could be used to propel a submarine beneath the surface of the sea. Instead of taking air from above the surface of the sea, Walter’s engine used hydrogen peroxide, H2O2, to provide oxygen for a conventional diesel engine.

Hydrogen peroxide may be catalytically decomposed to give water and oxygen.

(a) (i) What is meant by the term catalyst?

..................................................................................................................................

..................................................................................................................................

(ii) Construct a balanced equation for the decomposition of H2O2.

............................................................................................................................. [3]

Diesel fuel may be considered to consist of the hydrocarbon C15H32 which reacts completely with oxygen according to the following equation.

C15H32 + 23O2 → 15CO2 + 16H2O

(b) (i) To which homologous series does C15H32 belong?

................................................

(ii) Use the equation above and your answer to (a)(ii) to calculate the amount, in moles, of H2O2, that will provide sufficient oxygen for the complete oxidation of one mole of C15H32.

amount of H2O2 = ................................. mol

[3]



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A submarine equipped with a Walter engine used 212 tonnes of diesel fuel during an underwater voyage. The submarine also carried concentrated aqueous H2O2.

[1 tonne = 106 g] (c) (i) Calculate the amount, in moles, of diesel fuel used during the underwater voyage.

amount of diesel fuel = ................................. mol

(ii) Use your answers to (b)(ii) and (c)(i) to calculate the mass, in tonnes, of hydrogen peroxide used during the underwater voyage.

mass of H2O2 = ................................. tonnes[4]

(d) The exhaust products of the Walter engine were passed into the sea. What would happen to them?

..................................................................................................................................... [1]

[Total: 11]



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2 Ketene, C2H2O, is a member of a class of unsaturated organic compounds that is widely used in pharmaceutical research for the synthesis of organic compounds.

CH2=C=O

ketene

(a) (i) Suggest values for the H-C-H and C=C=O bond angles in ketene.

H-C-H …………………………………… C=C=O ……………………………………

(ii) By considering the structure of the molecule, suggest why the name ketene is used.

..................................................................................................................................

............................................................................................................................. [3]

(b) Ketene burns completely in air to form carbon dioxide and water.

(i) Write a balanced equation for this reaction.

..................................................................................................................................

(ii) Use your equation to calculate the volume of CO2, in dm3, measured at room temperature and pressure, which will be formed when 3.5g of ketene are burned in an excess of air.

Give your answer to two significant figures.

volume of CO2 = ................................. dm3 [4]



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(c) (i) Define the term standard enthalpy change of formation.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Use the data below to calculate the standard enthalpy change of formation of ketene.

∆H o/kJ mol–1

standard enthalpy change of formation of CO2

–395

standard enthalpy change of combustion of H2

–286

standard enthalpy change of combustion of CH2=C=O

–1028

[6]

(d) Ketene can be converted directly into ethanoic acid, CH3CO2H, by reaction with a compound A.

Suggest the identity of A.

.................………………................ [1]

[Total: 14]



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3 Chlorine gas is manufactured by the electrolysis of brine using a diaphragm cell.

(a) Write half-equations, including state symbols, for the reactions occurring at each of the electrodes of a diaphragm cell.

anode ...............................................................................................................................

cathode ....................................................................................................................... [2]

(b) In the diaphragm cell, the anode is made of titanium and the cathode is made of steel.

Suggest why steel is never used for the anode.

..........................................................................................................................................

..................................................................................................................................... [1]

(c) One important product made in the diaphragm cell is formed in aqueous solution.

(i) What substance is produced in aqueous solution in the diaphragm cell?

..................................................................................................................................

(ii) Explain, with the aid of appropriate half-equation(s), how this compound is formed by electrolysis.

..................................................................................................................................

..................................................................................................................................

............................................................................................................................. [3]

(d) Chlorine is very reactive and will form compounds by direct combination with many elements.

Describe what you would see when chlorine is passed over separate heated samples of sodium and phosphorus. In each case write an equation for the reaction.

sodium .............................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

phosphorus ......................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [4]



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(e) Magnesium chloride, MgCl2, and silicon tetrachloride, SiCl4, each dissolve in or react with water.

Suggest the approximate pH of the solution formed in each case.

MgCl2 ………………………………… SiCl4 …………………………………

Explain, with the aid of an equation, the difference between the two values.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [5]

[Total: 15]



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4 Organic chemistry is the chemistry of carbon compounds. The types of organic reactions that you have studied are listed below.

addition elimination hydrolysis

oxidation reduction substitution

Addition and substitution reactions are further described as follows.

electrophilic nucleophilic free radical

Complete the table below.

Fill in the central column by using only the types of reaction given in the lists above. Use both lists when appropriate.

In the right hand column give the name(s) or formula(e) of the reagent(s) you would use to carry out the reaction given.

organic reaction type of reaction reagent(s)

CH3CHO →

CH3CH(OH)CN

CH3CH2CH2CH3 →

CH3CH2CHBrCH3

CH3CH(OH)CH3 →

CH3CH=CH2

CH3CH=CH2 →

CH3CH(OH)CH2OH

[Total: 10]



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5 An organic ester, B, has the empirical formula C2H4O. An experiment by a student in a college gave a value of 87.5 for Mr of B.

(a) What is the molecular formula of B?

………………………… [1]

(b) In the boxes below, draw the structural formulae of four isomers of B that are esters.

W X

Y Z[4]



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The student hydrolysed his sample of B by heating with aqueous mineral acid and then separating the alcohol, C, that was formed. He heated the alcohol C under reflux with acidified dichromate(VI) ions and collected the product D.

A sample of D gave an orange precipitate with 2,4-dinitrophenylhydrazine reagent. A second sample of D gave no reaction with Tollens’ reagent.

(c) (i) What group does the reaction with 2,4-dinitrophenylhydrazine reagent show to be present in D?

………………………………………

(ii) What does the result of the test with Tollens’ reagent show about D?

………………………………………

(iii) What is the structural formula of the alcohol C?

(iv) Which of your esters, W, X, Y, or Z has the same structure as that of the ester B?

……………… [4]

(d) Which, if any of your esters, W, X, Y, or Z is chiral? Explain your answer.

..........................................................................................................................................

..................................................................................................................................... [1]

[Total: 10]



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DC SJF4800/DT 15628/4© UCLES 2009 [Turn over






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CHEMISTRY 9701/21


1 hour 15 minutes




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1 Magnesium, Mg, and radium, Ra, are elements in Group II of the Periodic Table.

Magnesium has three isotopes.

(a) Explain the meaning of the term isotope.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

A sample of magnesium has the following isotopic composition by mass.

isotope mass 24 25 26

% by mass 78.60 10.11 11.29

(b) Calculate the relative atomic mass, Ar, of magnesium to four significant figures.

Ar = ………………[2]



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Radium, proton number 88, and uranium, proton number 92, are radioactive elements.

The isotope 226Ra is produced by the radioactive decay of the uranium isotope 238U.

(c) Complete the table below to show the atomic structures of the isotopes 226Ra and 238U.

number of

isotopes protons neutrons electrons

226Ra

238U[3]

(d) Radium, like other Group II elements, forms a number of ionic compounds.

(i) What is the formula of the radium cation?

………………

(ii) Use the Data Booklet to suggest a value for the energy required to form one mole of the gaseous radium cation you have given in (i) from one mole of gaseous radium atoms. Explain your answer.

..................................................................................................................................

..................................................................................................................................

............................................................................................................................. [3]

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2 Radium was discovered in the ore pitchblende by Marie and Pierre Curie in 1898, and the metal was first isolated by them in 1910.

The metal was obtained by first reacting the radium present in the pitchblende to form

insoluble radium sulfate which was converted into aqueous radium bromide. This solution was then electrolysed using a mercury cathode and a carbon anode.

(a) Radium has chemical reactions that are typical of Group II metals and forms ionic compounds.

(i) What is the characteristic feature of the electronic configurations of all Group II metals?

..................................................................................................................................

(ii) Radium sulfate is extremely insoluble. From your knowledge of the simple salts of Group II metals, suggest another very insoluble radium salt.

................................................ [2]

(b) During their electrolysis of aqueous radium bromide, the Curies obtained radium at the cathode and bromine at the anode.

Write half-equations for the two electrode reactions that take place during this electrolysis.

anode ...............................................................................................................................

cathode ....................................................................................................................... [2]

(c) (i) Describe what you would see when magnesium reacts with

cold water, ................................................................................................................

..................................................................................................................................

steam. .......................................................................................................................

..................................................................................................................................

(ii) Write an equation for the reaction with steam.

..................................................................................................................................[5]



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(d) Radium reacts vigorously when added to water.

(i) Write an equation, with state symbols, for this reaction.

..................................................................................................................................

(ii) State two observations that could be made during this reaction.

..................................................................................................................................

..................................................................................................................................

(iii) Suggest the approximate pH of the resulting solution.

………………

(iv) Will the reaction be more or less vigorous than the reaction of barium with water?

Explain your answer.

..................................................................................................................................

..................................................................................................................................[6]

[Total: 15]



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3 Alkanes such as methane, CH4, undergo few chemical reactions. Methane will, however, react with chlorine but not with iodine.

Relevant standard enthalpy changes of formation for the reaction of methane with chlorine to form chloromethane, CH3Cl, are given below.

∆H f o /kJ mol–1

CH4 –75

CH3Cl –82

HCl –92

(a) (i) Use the data to calculate ∆H reaction for the formation of CH3Cl.

CH4 + Cl2 → CH3Cl + HCl

(ii) The corresponding reaction with iodine does not take place.

Use bond energy data from the Data Booklet to calculate a ‘theoretical value’ for ∆Hreaction for the following equation.

CH4 + I2 → CH3I + HI

(iii) Suggest why this reaction does not in fact occur.

..................................................................................................................................

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(b) (i) By using equations, describe the mechanism of the reaction between chlorine and methane to form chloromethane, CH3Cl.

Identify, by name, the separate steps of the overall reaction.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) What is the intermediate organic species in this reaction?

.............................................. [7] (c) The energy of activation for the formation of CH3Cl is 16 kJ mol–1. Use this figure and your answer to (a)(i) to complete the reaction pathway diagram

below showing the formation of CH3Cl from CH4 and Cl2. Show clearly the intermediate organic species and the final products. Indicate on your sketch the relevant enthalpy changes and their values.

enthalpy

progress of reaction

CH4 + Cl2

[4]

[Total: 16]



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4 The structural formulae of six different compounds, A – F, are given below. Each compound contains four carbon atoms in its molecule.

CH3CH=CHCH3 CH3CH2COCH3 CH2=CHCH2CH3

A B C

CH3CH2CH(OH)CH3 HOCH2CH2CH2CH2OH CH3CH2OCH2CH3

D E F

(a) (i) What is the empirical formula of compound E? ………………

(ii) Draw the skeletal formula of compound D.

(iii) Structural formulae do not show all of the isomers that may exist for a given molecular formula. Which two compounds each show different types of isomerism and what type of isomerism does each compound show? Identify each compound by its letter.

compound type of isomerism

[4]

Compound D may be converted into compound C. (b) (i) What type of reaction is this?

………………………………………

(ii) What reagent would you use for this reaction?

………………………………………

(iii) What is formed when compound E undergoes the same reaction using an excess of the same reagent?

……………………………………… [3]



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Compound A may be converted into compound B in a two-stage reaction.

CH3CH=CHCH3 →stage I

intermediate →stage II CH3CH2COCH3

(c) (i) What is the structural formula of the intermediate compound formed in this sequence?

(ii) Outline how stage I may be carried out to give this intermediate compound.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(iii) What reagent would be used for stage II?

………………………………………… [4]

(d) Compounds D and F are isomers.

What type of isomerism do they show?

………………………………………… [1]

[Total: 12]



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5 Three organic compounds, G, H, and J, each have the empirical formula CH2O. The numbers of carbon atoms in their molecules are shown in the table.

compoundnumber of C

atoms

G 1

H 2

J 3

In H and in J, the carbon atoms are bonded directly to one another. G gives a silver mirror when treated with Tollens’ reagent. H and J each give a brisk effervescence with Na2CO3(aq).

(a) Identify G.

……………………………………… [1]

(b) (i) What functional group is common to both H and J?

………………………………………

(ii) Identify H.

………………………………………

(iii) Identify J.

……………………………………… [3]

(c) When J is heated under reflux with acidified K2Cr2O7, the product, K, gives a red-orange precipitate with 2,4-dinitrophenylhydrazine reagent.

Draw the structural formula of K, the compound formed from J.

[1]



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(d) When J is warmed with concentrated sulfuric acid, a cyclic compound, L, is formed. L has the molecular formula C6H8O4.

(i) Suggest a displayed formula for L.

(ii) What type of reaction occurs when L is formed from J?

……………………………………… [2]

[Total: 7]



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CHEMISTRY 9701/22


1 hour 15 minutes




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1 The elements carbon and silicon are both in Group IV of the Periodic Table. Carbon is the second most abundant element by mass in the human body and silicon is the

second most common element in the Earth’s crust.

Carbon and silicon each form an oxide of general formula XO2. At room temperature, CO2 is a gas while SiO2 is a solid with a high melting point.

(a) Briefly explain, in terms of the chemical bonds and intermolecular forces present in each compound, why CO2 is a gas and SiO2 is a solid at room temperature.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [3]

(b) Draw a simple diagram to show the structure of SiO2. Your diagram should contain at least two silicon atoms and show clearly how many bonds each atom forms.

[2]

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CO2 does not behave as an ideal gas.

(c) (i) State the basic assumptions of the kinetic theory as applied to an ideal gas.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Suggest one reason why CO2 does not behave as an ideal gas.

..................................................................................................................................[5]

Carbon exists in a number of forms, one of which is a conductor of electricity and one of which is a non-conductor of electricity. Silicon is the main component of most semi-conductors.

(d) Graphite is the form of carbon that is a conductor of electricity. Give a simple explanation for this property.

..........................................................................................................................................

.................................................................................................................................... [1]

When carbon and silicon(IV) oxide are heated together at about 2000 °C, silicon carbide, SiC, is formed. Silicon carbide is a hard material which is widely used as an abrasive and in ceramics.

(e) (i) Construct an equation for the reaction of carbon and silicon(IV) oxide.

..................................................................................................................................

(ii) SiC has a similar structure to one of the common forms of carbon. Which form is this? Give a reason for your answer.

form ...........................................................

reason ......................................................................................................................[2]

[Total: 13]



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ForExaminer’s

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2 The elements of the third period of the Periodic Table form chlorides of general formula ECl x where E represents the element. These chlorides show a variation in oxidation number from sodium to sulfur.

(a) (i) Use the information given to complete the table below.

formula of chloride NaCl MgCl 2 Al Cl 3 SiCl 4 PCl 3 SCl 2

oxidation number of element in the chloride

(ii) By considering the electron configurations of the elements, explain the variation in oxidation number in the chlorides from Na to Al and from Si to S.

Na to Al ....................................................................................................................

..................................................................................................................................

Si to S .......................................................................................................................

..................................................................................................................................[5]

Sodium hydride, NaH, is a colourless crystalline solid which melts at 800 °C and has the same crystal structure as sodium chloride which has a melting point of 808 °C. When molten sodium chloride is electrolysed using graphite electrodes, a shiny deposit, D, forms on the cathode and a greenish-yellow gas is evolved from the anode. When molten sodium hydride is electrolysed, under suitable conditions using graphite electrodes, the same shiny deposit D is formed on the cathode and a colourless gas, G, is evolved from the anode.

(b) (i) Describe with the aid of a diagram the bonding in a sodium chloride crystal.

(ii) Suggest the type of bonding that is present in sodium hydride.

..................................................................................................................................

(iii) What is the oxidation number of hydrogen in sodium hydride?

.......................



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(iv) Draw a ‘dot-and-cross’ diagram for sodium hydride. Show outer electrons only.

(v) The metals magnesium and aluminium form hydrides with formulae MgH2 and Al H3. The non-metals phosphorus and sulfur form hydrides with formulae PH3 and H2S.

By considering their positions in the Periodic Table, suggest oxidation numbers for these four elements in their hydrides.

compound MgH2 Al H3 PH3 H2S

oxidation number of element in the hydride

[8]

At room temperature, the chlorides of sodium, magnesium and aluminium are all solids which dissolve in water.

The hydrides of sodium, magnesium and aluminium are also solids which react with water with the rapid evolution of the same colourless gas G in each case.

(c) (i) What is the pH of the solutions formed when separate samples of sodium chloride, magnesium chloride, and aluminium chloride are dissolved in water?

chloride sodium magnesium aluminium

pH

(ii) Suggest an equation for the reaction between sodium hydride and water.

..................................................................................................................................

(iii) Suggest a value for the pH of the solution formed in (ii).

.......................[4]

At room temperature, the chlorides of silicon, phosphorus and sulfur are all low melting point solids or low boiling point liquids that can be seen to react with water.

(d) (i) Suggest what type of bonding is present in sulfur dichloride, SCl 2.

...................................................................

(ii) Write a balanced equation for the reaction between the chloride of silicon, SiCl 4, and water.

............................................................................................................................ [2]

[Total: 19]



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9701/22/O/N/09© UCLES 2009

ForExaminer’s

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3 One method of making 1-bromobutane in the laboratory is described below.

Stage 1 Place 35 g of powdered sodium bromide, 30 cm3 of water, and 25 cm3 (20 g) of butan-1-ol, in a 250 cm3 two necked flask fitted with a tap funnel and reflux condenser.

Stage 2 Concentrated sulfuric acid (25 cm3) is then placed in the tap funnel and added drop by drop to the reagents in the flask, keeping the contents well shaken and cooled occasionally in an ice-water bath.

(a) The overall reaction may be considered to take place in two stages. In the first stage the inorganic reagents react together to form HBr. In the second stage, the organic reagent reacts with the HBr that is formed in the first stage.

Write an equation for each of these stages.

stage I ..............................................................................................................................

stage II ....................................................................................................................... [2]

(b) In this preparation, by using the amounts given above, one of the reagents, sodium bromide or butan-1-ol, will be present in an excess.

Use your equations in (a) and the data above to determine, by calculation, which reagent is in an excess.

[2]

(c) In a laboratory preparation of 1-bromobutane, when 15.4 g of butan-1-ol was used, 22.5 g of 1-bromobutane was obtained after purification.

Calculate the yield of 1-bromobutane as a percentage of the theoretical maximum yield.

[2]



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(d) When the concentrated sulfuric acid is added to the reaction mixture (stage 2), unless the temperature is controlled carefully, the acid may react with either of the original reactants (sodium bromide or butan-1-ol) to give at least two by-products, one of which is inorganic and the other organic.

What inorganic and organic by-products may be formed?

In each case, identify one by-product and state the role of the concentrated sulfuric acid in the formation of this by-product.

inorganic by-product ............................

role of conc. H2SO4 ..........................................................................................................

organic by-product ...............................

role of conc. H2SO4 .................................................................................................... [4]

[Total: 10]



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9701/22/O/N/09© UCLES 2009

ForExaminer’s

Use

4 (a) Complete the following reaction scheme which starts with 1-bromobutane. In each empty box, write the structural formula of the organic compound that would

be formed.

CH3CH2CH2CH2Br

K2Cr2O7/H+

heat underreflux

conc. KMnO4/H+

heat underreflux

NaOH(aq) NaOH in ethanolheat underreflux

heat underreflux

W

Y

X

Z

[4]



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(b) One of the compounds W, X, Y or Z can be polymerised.

(i) Identify this compound by its letter.

.......................

(ii) Draw a section of the polymer chain formed by this compound.

Show two repeat units.

[2]

[Total: 6]



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9701/22/O/N/09© UCLES 2009

ForExaminer’s

Use

5 The fermentation of starch or molasses using the bacterium Clostridium acetobutylicum, produces a mixture of propanone and butan-1-ol.

(a) Give the reagent(s) and state what would be observed when one test is carried out to confirm the presence of propanone in a mixture of propanone and butan-1-ol.

reagent(s) ........................................................................................................................

observation ................................................................................................................ [2]

(b) What will be observed when a small piece of sodium metal is dropped into a dry sample of butan -1-ol? Write an equation for the reaction that takes place.

observation ......................................................................................................................

equation ..................................................................................................................... [2]

The molecular formula C5H12O represents a number of alcohols. Three alcohols with molecular formula C5H12O are straight chain pentanols.

(c) Draw the following formulae.

(i) the structural formula of pentan-1-ol

(ii) the displayed formula of pentan-2-ol

(iii) the skeletal formula of pentan-3-ol

[3]



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9701/22/O/N/09© UCLES 2009

ForExaminer’s

Use

When one of the three pentanols in (c) is dehydrated, alkenes with two different structural formulae are formed.

(d) Identify this alcohol and give the structural formula of each alkene.

name of alcohol .........................................

alkene 1 alkene 2

[3]

A number of alcohols with molecular formula C5H12O are branched chain compounds and may be considered as derivatives of butanol or propanol with alkyl side chains.

(e) (i) Draw the structural formula of the derivative of propanol that has the molecular formula C5H12O.

(ii) Draw the structural formula of the organic compound that will be present when the derivative of propanol you have given in (i) is heated under reflux with acidified potassium dichromate(VI).

[2]

[Total: 12]



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1 In 1814, Sir Humphrey Davy and Michael Faraday collected samples of a flammable gas, A, from the ground near Florence in Italy.

They analysed A which they found to be a hydrocarbon. Further experiments were then carried out to determine the molecular formula of A.

(a) What is meant by the term molecular formula?

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

Davy and Faraday deduced the formula of A by exploding it with an excess of oxygen and analysing the products of combustion.

(b) Complete and balance the following equation for the complete combustion of a hydrocarbon with the formula CxHy .

CxHy + (x + y4)O2 ................................ + ................................

[2]

(c) When 10 cm3 of A was mixed at room temperature with 50 cm3 of oxygen (an excess) and exploded, 40 cm3 of gas remained after cooling the apparatus to room temperature and pressure.

When this 40 cm3 of gas was shaken with an excess of aqueous potassium hydroxide, KOH, 30 cm3 of gas still remained.

(i) What is the identity of the 30 cm3 of gas that remained at the end of the experiment?

...................................................

(ii) The combustion of A produced a gas that reacted with the KOH(aq).

What is the identity of this gas?

...................................................

(iii) What volume of the gas you have identified in (ii) was produced by the combustion of A?

...............................cm3

(iv) What volume of oxygen was used up in the combustion of A?

...............................cm3 [4]



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(d) Use your equation in (b) and your results from (c)(iii) and (c)(iv) to calculate the molecular formula of A.

Show all of your working.

[3]

[Total: 11]



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ForExaminer’s

Use

2 Nitrogen makes up about 79% of the Earth’s atmosphere. As a constituent element of proteins, it is present in living organisms.

Atmospheric nitrogen is used in the Haber process for the manufacture of ammonia.

(a) Write an equation for the formation of ammonia in the Haber process.

...................................................................................................................................... [1]

(b) The Haber process is usually carried out at a high pressure of between 60 and 200 atmospheres (between 60 × 105 Pa and 200 × 105 Pa).

State two further important operating conditions that are used in the Haber process. For each of your conditions, explain why it is used.

condition 1 .......................................................................

reason ..............................................................................................................................

condition 2 .......................................................................

reason .......................................................................................................................... [4]

(c) State one large-scale use for ammonia, other than in the production of nitrogenous fertilisers.

................................................... [1]

(d) The uncontrolled use of nitrogenous fertilisers can cause environmental damage to lakes and streams. This is known as ‘eutrophication’.

What are the processes that occur when excessive amounts of nitrogenous fertilisers get into lakes and streams?

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]



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In many countries, new cars have to comply with regulations which are intended to reduce the pollutants coming from their internal combustion engines.

Two pollutants that may be formed in an internal combustion engine are carbon monoxide, CO, and nitrogen monoxide, NO.

(e) (i) Outline how each of these pollutants may be formed in an internal combustion engine.

CO ............................................................................................................................

..................................................................................................................................

NO ............................................................................................................................

.................................................................................................................................. (ii) State the main hazard associated with each of these pollutants.

CO ....................................................................

NO .................................................................... [4]

Pollutants such as CO and NO are removed from the exhaust gases of internal combustion engines by catalytic converters which are placed in the exhaust system of a car.

(f) (i) What metal is most commonly used as the catalyst in a catalytic converter?

...................................................

(ii) Construct one balanced equation for the reaction in which both CO and NO are removed from the exhaust gases by a catalytic converter.

.............................................................................................................................. [2]

[Total: 14]



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ForExaminer’s

Use

3 Crude oil is a naturally occurring flammable liquid which consists of a complex mixture of hydrocarbons. In order to separate the hydrocarbons the crude oil is subjected to fractional distillation.

(a) Explain what is meant by the following terms.

(i) hydrocarbon .............................................................................................................

..................................................................................................................................

(ii) fractional distillation ..................................................................................................

.............................................................................................................................. [2]

(b) Undecane, C11H24, is a long chain hydrocarbon which is present in crude oil. Such long chain hydrocarbons are ‘cracked’ to produce alkanes and alkenes which have

smaller molecules.

(i) Give the conditions for two different processes by which long chain molecules may be cracked.

process 1 ..................................................................................................................

..................................................................................................................................

process 2 ..................................................................................................................

..................................................................................................................................

(ii) Undecane, C11H24, can be cracked to form pentane, C5H12, and an alkene. Construct a balanced equation for this reaction.

.............................................................................................................................. [3]

Pentane, C5H12, exhibits structural isomerism.

(c) (i) Draw the three structural isomers of pentane.

isomer B isomer C isomer D



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(ii) The three isomers of pentane have different boiling points.

Which of your isomers has the highest boiling point?

isomer .........

Suggest an explanation for your answer.

..................................................................................................................................

..................................................................................................................................

.............................................................................................................................. [6]

The unsaturated hydrocarbon, E, is obtained by cracking hexane and is important in the chemical industry.

The standard enthalpy change of combustion of E is –2059 kJ mol–1.


..........................................................................................................................................

...................................................................................................................................... [2]

When 0.47 g of E was completely burnt in air, the heat produced raised the temperature of 200 g of water by 27.5 °C. Assume no heat losses occurred during this experiment.

(e) (i) Use relevant data from the Data Booklet to calculate the amount of heat released in this experiment.

(ii) Use the data above and your answer to (i) to calculate the relative molecular mass, Mr, of E.

[4]

(f) Deduce the molecular formula of E.

[1]

[Total: 18]



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9701/21/O/N/10© UCLES 2010

ForExaminer’s

Use

4 Halogenoalkanes have many chemical uses, particularly as intermediates in organic reactions.

Three reactions of 1-bromobutane, CH3CH2CH2CH2Br, are shown below.

CH3CH2CH2CH2OH CH3CH2CH2CH2NH2

CH3CH2CH2CH2Br

CH3CH2CH=CH2

reaction 1 reaction 2

reaction 3

(a) For each reaction, state the reagent and solvent used.

reaction 1 reagent ............................................................

solvent .............................................................


solvent .............................................................


solvent ............................................................. [6]

(b) When 1-iodobutane, CH3CH2CH2CH2I, is reacted under the same conditions as those used in reaction 1, butan-1-ol is formed.

What difference, if any, would there be in the rate of this reaction compared to the reaction of 1-bromobutane?

Use appropriate data from the Data Booklet to explain your answer.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [3]



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Dichlorodifluoromethane, CCl2F2, is an example of a chlorofluorocarbon (CFC) that was formerly used as an aerosol propellant. In September 2007, at the Montreal summit, approximately 200 countries agreed to phase out the use of CFCs by 2020.

(c) State two properties of CFCs that made them suitable as aerosol propellants.

1. .......................................................................................

2. ....................................................................................... [2]

(d) When CFCs are present in the upper atmosphere, homolytic fission takes place in the presence of ultraviolet light.

(i) What is meant by the term homolytic fission?

..................................................................................................................................

..................................................................................................................................

(ii) Suggest an equation for the homolytic fission of CCl2F2.

.............................................................................................................................. [2]

(e) The most common replacements for CFCs as aerosol propellants are hydrocarbons such as propane and butane.

Suggest one disadvantage of these compounds as aerosol propellants.

...................................................................................................................................... [1]

[Total: 14]



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5 The gaseous hydrogen halides HCl, HBr and HI, may be prepared by reacting the corresponding sodium salt with anhydrous phosphoric(V) acid, H3PO4.

When the sodium halide NaX was used, the following reaction occurred and a sample of gaseous HX was collected in a gas jar.

NaX + H3PO4 NaH2PO4 + HX A hot glass rod was placed in the sample of HX and immediately a red/orange colour was

observed.

(a) What is the identity of NaX?

................................................... [1]

(b) What gas, other than HX, would be formed if concentrated sulfuric acid were used with NaX instead of phosphoric(V) acid?

................................................... [1]

(c) Suggest why phosphoric(V) acid rather than concentrated sulfuric acid is used to make samples of HX from the corresponding sodium salt.


..........................................................................................................................................

...................................................................................................................................... [1]

[Total: 3]




DC (CW/KN) 34037© UCLES 2010 [Turn over






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CHEMISTRY 9701/22


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1 In 1814, Sir Humphrey Davy and Michael Faraday collected samples of a flammable gas, A, from the ground near Florence in Italy.

They analysed A which they found to be a hydrocarbon. Further experiments were then carried out to determine the molecular formula of A.

(a) What is meant by the term molecular formula?

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

Davy and Faraday deduced the formula of A by exploding it with an excess of oxygen and analysing the products of combustion.

(b) Complete and balance the following equation for the complete combustion of a hydrocarbon with the formula CxHy .

CxHy + (x + y4)O2 ................................ + ................................

[2]

(c) When 10 cm3 of A was mixed at room temperature with 50 cm3 of oxygen (an excess) and exploded, 40 cm3 of gas remained after cooling the apparatus to room temperature and pressure.

When this 40 cm3 of gas was shaken with an excess of aqueous potassium hydroxide, KOH, 30 cm3 of gas still remained.

(i) What is the identity of the 30 cm3 of gas that remained at the end of the experiment?

...................................................

(ii) The combustion of A produced a gas that reacted with the KOH(aq).

What is the identity of this gas?

...................................................

(iii) What volume of the gas you have identified in (ii) was produced by the combustion of A?

...............................cm3

(iv) What volume of oxygen was used up in the combustion of A?

...............................cm3 [4]



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(d) Use your equation in (b) and your results from (c)(iii) and (c)(iv) to calculate the molecular formula of A.

Show all of your working.

[3]

[Total: 11]



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9701/22/O/N/10© UCLES 2010

ForExaminer’s

Use

2 Nitrogen makes up about 79% of the Earth’s atmosphere. As a constituent element of proteins, it is present in living organisms.

Atmospheric nitrogen is used in the Haber process for the manufacture of ammonia.

(a) Write an equation for the formation of ammonia in the Haber process.

...................................................................................................................................... [1]

(b) The Haber process is usually carried out at a high pressure of between 60 and 200 atmospheres (between 60 × 105 Pa and 200 × 105 Pa).

State two further important operating conditions that are used in the Haber process. For each of your conditions, explain why it is used.

condition 1 .......................................................................

reason ..............................................................................................................................

condition 2 .......................................................................

reason .......................................................................................................................... [4]

(c) State one large-scale use for ammonia, other than in the production of nitrogenous fertilisers.

................................................... [1]

(d) The uncontrolled use of nitrogenous fertilisers can cause environmental damage to lakes and streams. This is known as ‘eutrophication’.

What are the processes that occur when excessive amounts of nitrogenous fertilisers get into lakes and streams?

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]



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In many countries, new cars have to comply with regulations which are intended to reduce the pollutants coming from their internal combustion engines.

Two pollutants that may be formed in an internal combustion engine are carbon monoxide, CO, and nitrogen monoxide, NO.

(e) (i) Outline how each of these pollutants may be formed in an internal combustion engine.

CO ............................................................................................................................

..................................................................................................................................

NO ............................................................................................................................

.................................................................................................................................. (ii) State the main hazard associated with each of these pollutants.

CO ....................................................................

NO .................................................................... [4]

Pollutants such as CO and NO are removed from the exhaust gases of internal combustion engines by catalytic converters which are placed in the exhaust system of a car.

(f) (i) What metal is most commonly used as the catalyst in a catalytic converter?

...................................................

(ii) Construct one balanced equation for the reaction in which both CO and NO are removed from the exhaust gases by a catalytic converter.

.............................................................................................................................. [2]

[Total: 14]



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9701/22/O/N/10© UCLES 2010

ForExaminer’s

Use

3 Crude oil is a naturally occurring flammable liquid which consists of a complex mixture of hydrocarbons. In order to separate the hydrocarbons the crude oil is subjected to fractional distillation.

(a) Explain what is meant by the following terms.

(i) hydrocarbon .............................................................................................................

..................................................................................................................................

(ii) fractional distillation ..................................................................................................

.............................................................................................................................. [2]

(b) Undecane, C11H24, is a long chain hydrocarbon which is present in crude oil. Such long chain hydrocarbons are ‘cracked’ to produce alkanes and alkenes which have

smaller molecules.

(i) Give the conditions for two different processes by which long chain molecules may be cracked.

process 1 ..................................................................................................................

..................................................................................................................................

process 2 ..................................................................................................................

..................................................................................................................................

(ii) Undecane, C11H24, can be cracked to form pentane, C5H12, and an alkene. Construct a balanced equation for this reaction.

.............................................................................................................................. [3]

Pentane, C5H12, exhibits structural isomerism.

(c) (i) Draw the three structural isomers of pentane.

isomer B isomer C isomer D



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(ii) The three isomers of pentane have different boiling points.

Which of your isomers has the highest boiling point?

isomer .........

Suggest an explanation for your answer.

..................................................................................................................................

..................................................................................................................................

.............................................................................................................................. [6]

The unsaturated hydrocarbon, E, is obtained by cracking hexane and is important in the chemical industry.

The standard enthalpy change of combustion of E is –2059 kJ mol–1.


..........................................................................................................................................

...................................................................................................................................... [2]

When 0.47 g of E was completely burnt in air, the heat produced raised the temperature of 200 g of water by 27.5 °C. Assume no heat losses occurred during this experiment.

(e) (i) Use relevant data from the Data Booklet to calculate the amount of heat released in this experiment.

(ii) Use the data above and your answer to (i) to calculate the relative molecular mass, Mr, of E.

[4]

(f) Deduce the molecular formula of E.

[1]

[Total: 18]



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9701/22/O/N/10© UCLES 2010

ForExaminer’s

Use

4 Halogenoalkanes have many chemical uses, particularly as intermediates in organic reactions.

Three reactions of 1-bromobutane, CH3CH2CH2CH2Br, are shown below.

CH3CH2CH2CH2OH CH3CH2CH2CH2NH2

CH3CH2CH2CH2Br

CH3CH2CH=CH2

reaction 1 reaction 2

reaction 3

(a) For each reaction, state the reagent and solvent used.


solvent .............................................................


solvent .............................................................


solvent ............................................................. [6]

(b) When 1-iodobutane, CH3CH2CH2CH2I, is reacted under the same conditions as those used in reaction 1, butan-1-ol is formed.

What difference, if any, would there be in the rate of this reaction compared to the reaction of 1-bromobutane?

Use appropriate data from the Data Booklet to explain your answer.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [3]



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Dichlorodifluoromethane, CCl2F2, is an example of a chlorofluorocarbon (CFC) that was formerly used as an aerosol propellant. In September 2007, at the Montreal summit, approximately 200 countries agreed to phase out the use of CFCs by 2020.

(c) State two properties of CFCs that made them suitable as aerosol propellants.

1. .......................................................................................

2. ....................................................................................... [2]

(d) When CFCs are present in the upper atmosphere, homolytic fission takes place in the presence of ultraviolet light.

(i) What is meant by the term homolytic fission?

..................................................................................................................................

..................................................................................................................................

(ii) Suggest an equation for the homolytic fission of CCl2F2.

.............................................................................................................................. [2]

(e) The most common replacements for CFCs as aerosol propellants are hydrocarbons such as propane and butane.

Suggest one disadvantage of these compounds as aerosol propellants.

...................................................................................................................................... [1]

[Total: 14]



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ForExaminer’s

Use

5 The gaseous hydrogen halides HCl, HBr and HI, may be prepared by reacting the corresponding sodium salt with anhydrous phosphoric(V) acid, H3PO4.

When the sodium halide NaX was used, the following reaction occurred and a sample of gaseous HX was collected in a gas jar.

NaX + H3PO4 NaH2PO4 + HX A hot glass rod was placed in the sample of HX and immediately a red/orange colour was

observed.

(a) What is the identity of NaX?

................................................... [1]

(b) What gas, other than HX, would be formed if concentrated sulfuric acid were used with NaX instead of phosphoric(V) acid?

................................................... [1]

(c) Suggest why phosphoric(V) acid rather than concentrated sulfuric acid is used to make samples of HX from the corresponding sodium salt.


..........................................................................................................................................

...................................................................................................................................... [1]

[Total: 3]




DC (CW) 21611/2© UCLES 2010 [Turn over






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CHEMISTRY 9701/23


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1 The element magnesium, Mg, proton number 12, is a metal which is used in many alloys which are strong and light.

Magnesium has several naturally occurring isotopes. (a) What is meant by the term isotope?

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

(b) Complete the table below for two of the isotopes of magnesium.

isotopenumber of

protonsnumber of neutrons

number of electrons

24Mg

26Mg

[2]

A sample of magnesium had the following isotopic composition: 24Mg, 78.60%; 25Mg, 10.11%; 26Mg, 11.29%.

(c) Calculate the relative atomic mass, Ar, of magnesium in the sample. Express your answer to an appropriate number of significant figures.

[2]



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Antimony, Sb, proton number 51, is another element which is used in alloys.

Magnesium and antimony each react when heated separately in chlorine.

(d) Construct a balanced equation for the reaction between magnesium and chlorine.

...................................................................................................................................... [1]

When a 2.45 g sample of antimony was heated in chlorine under suitable conditions, 4.57 g of a chloride A were formed.

(e) (i) Calculate the amount, in moles, of antimony atoms that reacted.


(iii) Use your answers to (i) and (ii) to determine the empirical formula of A.

(iv) The empirical and molecular formulae of A are the same.

Construct a balanced equation for the reaction between antimony and chlorine.

.............................................................................................................................. [5]

(f) The chloride A melts at 73.4 °C while magnesium chloride melts at 714 °C.

(i) What type of bonding is present in magnesium chloride?

..................................................................................................................................

(ii) Suggest what type of bonding is present in A.

.............................................................................................................................. [2]

[Total: 14]



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2 Sulfur and its compounds are found in volcanoes, in organic matter and in minerals. Sulfuric acid, an important industrial chemical, is manufactured from sulfur by the Contact

process. The Contact process may be considered to be a three-stage process in which sulfur is

converted into sulfuric acid. Each stage consists of a single chemical reaction.

(a) Write a balanced equation for each of these reactions in the correct sequence. Where appropriate, use to indicate that the reaction is an equilibrium.

first reaction .....................................................................................................................

second reaction ...............................................................................................................

third reaction ................................................................................................................ [4]

(b) Give three different operating conditions that are used in the second stage.

condition 1 .......................................................................................................................

condition 2 .......................................................................................................................

condition 3 ................................................................................................................... [3]

(c) State one large scale use of sulfuric acid.

................................................................... [1]

(d) Most of the sulfur that is used in the Contact process is recovered from sulfur compounds present in crude oil and natural gas by using the Claus process.

(i) In this process, about one third of the hydrogen sulfide, H2S, present in the oil or gas, is converted into sulfur dioxide, SO2.

Balance the equation for this reaction.

.....H2S + .....O2 .....SO2 + .....H2O



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(ii) The SO2 formed is then reacted catalytically with the remaining H2S, producing sulfur and water.

2H2S + SO2 3S + 2H2O

What are the oxidation numbers of each of the sulfur-containing substances in this reaction?

H2S......... SO2 .......... S .......

Which substance is reduced? Explain your answer.

substance .............

explanation ........................................................................................................... [3]

The sulfur present in crude oil is removed in order to prevent the formation of sulfur dioxide when fuels such as petrol (gasoline) or diesel fuel are burned in internal combustion engines.

Other substances that may be present in the exhaust gases of motor vehicles include CO, CO2, NO/NO2, and unburnt hydrocarbons.

The emission of sulfur dioxide can produce ‘acid rain’.

(e) (i) Outline, with the aid of equations, how acid rain is formed from the exhaust gases of motor vehicles.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) State one environmental effect of acid rain.

.............................................................................................................................. [4]

(f) Sulfur dioxide is used to preserve dried fruits and vegetables.

What chemical property of SO2 enables it to be used as a food preservative?

...................................................................................................................................... [1]

[Total: 16]



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3 Astronomers using modern spectroscopic techniques of various types have found evidence of many molecules, ions and free radicals in the dust clouds in Space. Many of the species concerned have also been produced in laboratories on Earth.

Two such species are the dicarbon monoxide molecule, C2O, and the amino free radical, NH2.

(a) (i) Dicarbon monoxide can be produced in a laboratory and analysis of it shows that the sequence of atoms in this molecule is carbon-carbon-oxygen and there are no unpaired electrons, but one of the atoms is only surrounded by six electrons.

Draw a ‘dot-and-cross’ diagram of C2O and suggest the shape of the molecule.

shape ........................................

(ii) What is meant by the term free radical ?

..................................................................................................................................

..................................................................................................................................

(iii) Explain why NH2 is described as a ‘free radical’.

..................................................................................................................................

.............................................................................................................................. [5]

Two derivatives of ethene which have been detected in dust clouds in Space are acrylonitrile (2-propenenitrile), CH2=CHCN, and vinyl alcohol (ethenol), CH2=CHOH.

(b) Like ethene, acrylonitrile can be polymerised. The resulting polymer can be used to

make carbon fibres. (i) Draw the structural formula of the polymer made from acrylonitrile, showing two

repeat units.

(ii) What type of polymerisation is this reaction?

.............................................................................................................................. [2]



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Vinyl alcohol cannot be polymerised in the same way as acrylonitrile because it will readily isomerise into another common organic compound, Z.

(c) (i) Suggest the structural formula of the organic compound Z.

(ii) Suggest the structural formula of another isomer of vinyl alcohol which has a cyclic (ring) structure.

[2]

Acrolein (2-propenal), CH2=CHCHO, has also been found in Space.

(d) Give the structural formulae of the organic compounds formed when acrolein is reacted separately with each of the following reagents.

reagent product

Br2 in an inert solvent

NaCN + dilute H2SO4

Tollens’ reagent

NaBH4

[4]

[Total: 13]



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4 Although few halogenoalkanes exist naturally, such compounds are important as intermediates in organic reactions and as solvents.

The bromoalkane B has the following composition by mass: C, 29.3%; H, 5.7%; Br, 65.0%. The relative molecular mass of B is 123.

(a) Calculate the molecular formula of B.

[3]

Halogenoalkanes such as bromoethane, C2H5Br, have two different reactions with sodium hydroxide, NaOH, depending on the conditions used.

(b) (i) When hot aqueous NaOH is used, the C2H5Br is hydrolysed to ethanol, C2H5OH.

Describe the mechanism of this reaction. In your answer, show any relevant charges, dipoles, lone pairs of electrons and movement of electron pairs by curly arrows.



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(ii) What will be formed when C2H5Br is reacted with NaOH under different conditions?

..................................................................................................................................

(iii) What are the conditions used?

..................................................................................................................................

(iv) What type of reaction is this?

.............................................................................................................................. [7]

When 1,4-dichlorobutane, ClCH2CH2CH2CH2Cl, is reacted with NaOH, two different reactions can occur, depending on the conditions used.

(c) (i) Draw the displayed formula of the product formed when 1,4-dichlorobutane is

reacted with hot aqueous NaOH as in (b)(i).

(ii) Draw the skeletal formula of the product formed when 1,4-dichlorobutane is reacted with NaOH in the way you have described in (b)(ii) and (b)(iii).

[2]

[Total: 12]



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5 A student placed separate small samples of 1-chlorobutane, 1-bromobutane and, 1-iodobutane, in three separate test-tubes. To each test-tube, 1 cm3 of ethanol was added, followed by 1 cm3 of aqueous silver nitrate, AgNO3. The tubes were then carefully shaken, placed in a test-tube rack and observed for 30 minutes.

A precipitate was formed in each test-tube but not at the same time; the fastest taking about two minutes to become opaque and the slowest about 20 minutes.

(a) What is the identity of the precipitate formed when 1-chlorobutane is used?

...................................................................................................................................... [1]

(b) What will be the colour of this precipitate?

...................................................................................................................................... [1]

(c) Which of the three halogenoalkanes will produce a precipitate in about two minutes?

...................................................................................................................................... [1]

(d) Use appropriate data from the Data Booklet to explain why this reaction takes place most quickly of the three.

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

[Total: 5]



chemistry level) (cie) paper 2

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