QUESTION and ANSWER BOOKLET

Time allowed: Three hours

(An extra 10 minutes is allowed for reading this paper.)

South Pacific Form Seven Certificate

CHEMISTRY 2018

INSTRUCTIONS

Write your Student Personal Identification Number (SPIN) in the space provided on the top right-hand corner of this page.

Answer ALL QUESTIONS. Write your answers in the spaces provided in this booklet.

If you need more space for answers, ask the Supervisor for extra paper. Write your SPIN on all extra sheets used and clearly number the questions. Attach the extra sheets at the appropriate places in this booklet.

Major Learning Outcomes (Achievement Standards)

Skill Level & Number of Questions Weight/

Time Level 1

Uni-structural

Level 2 Multi-

structural

Level 3 Relational

Level 4 Extended Abstract

Strand 1: Atomic Structure, Bonding and Related Properties

Interpret information about selected properties of elements and compounds in relation to atomic structure.

10 4 1 1 25%

64 min

Strand 2: Energy Changes in Chemical and Physical Processes

Use thermochemical data to determine energy changes in chemical and physical processes.

2 3 1 0 11%

28 min

Strand 3: Aqueous Equilibrium Systems Relate the properties of aqueous solutions to the nature and concentration of dissolved species.

3 - 1 1 10%

26 min

Strand 4: Oxidation–Reduction Reactions Apply oxidation–reduction principles to electrochemical cells and compare the relative strength of oxidants and reductants, and deduce the direction of spontaneous reactions.

2 2 1 - 9%

23 min

Strand 5: Organic Chemistry Use information about the structure and reactions of organic molecules to solve problems in organic chemistry.

2 3 1 1 15%

39 min

TOTAL 19 12 5 3 70%

180 min

Check that this booklet contains pages 2-18 in the correct order and that none of these pages are blank.

HAND THIS BOOKLET TO THE SUPERVISOR AT THE END OF THE EXAMINATION.

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STRAND 1: ATOMIC STRUCTURE AND BONDING AND RELATED PROPERTIES

1.1a

Use the information below to answer questions 1.1a – 1.1d.

The boiling points of certain covalent molecules are shown in the table below.

Name of Compound

Structure of Molecule

Polarity Boiling Point (°C)

Methane

Non-polar -161.5

Chloromethane

Polar -24.2

Dichloromethane

Polar 39.8

Trichloromethane

Polar 61.7

Define polarity.

1.1b State the shape of trichloromethane.

1.1c Identify the inter-molecular force that is responsible for the low boiling point

of methane.

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1.1d Although the boiling points of the compounds increase down the group, the

greatest increase is between methane, CH4, and chloromethane, CH3Cl.

Explain this observation.

1.2 The ions Na1+, Mg2+ and Al3+ all have the same number of electrons.

Describe the trend in the size of their ionic radii.

1.3a

Use the information below to answer questions 1.3a – 1.3d.

Plutonium 239 is an extremely dangerous radioactive element, which is

often used as fuel for nuclear reactors. Plutonium 239 is produced from the

nuclear fission of Uranium 238, releasing high-speed electrons.

U92238 + X Pu94

239 + 2 𝑒−10

Define nuclear fission.

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1.3b Identify the unknown X.

1.3c State one property of high speed electrons.

1.3d Discuss one use of nuclear chemistry in everyday applications by relating

the properties of radioactive particles to its use.

Compare the advantages and disadvantages of the application, and

determine its overall value to human life.

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1.4a What are the three characteristic properties of transition elements?

1.4b Write down the electron configuration using s, p and d notation, for

the Cu2964

2+ ion.

1.4c

Use the information below to answer questions 1.4c – 1.4d.

Two transition metal complex ions are given in the following table.

Formula Colour Name

[CuCl4]2-

Tetrachlorocopper(II) ion

[Zn(OH)4] 2-

Colourless

State the colour of the complex ion [CuCl4]2-. _____________________________________________________________

1.4d State the name of the complex ion [Zn(OH)4] 2-. _____________________________________________________________

1.4e Give the name of the transition metal in the complex ion [Cu (NH3)4 ]2+ . _____________________________________________________________

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1.4f Write the balanced chemical equation for the formation of [Ag(NH3)2]1+.

1.4g Describe the colour change that takes place, and any observations that confirm [Ag(NH3)2]1+ has formed.

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STRAND 2: ENERGY CHANGES IN CHEMICAL AND PHYSICAL PROCESSES

2.1 Name the enthalpy change for the process.

Na (g) Na+(g) + e

2.2a

Use the information below to answer questions 2.2a – 2.2c.

Cooking gas contains the hydrocarbon propane, C3H8.

Write the thermochemical equation for the complete combustion of C3H8 gas.

2.2b Write the symbol for the enthalpy change of this reaction.

2.2c Describe how the use of propane gas in cooking is an example of an exothermic reaction.

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2.3 Ethene gas, C2H4 can be prepared by dehydrating ethanol as shown by the following equation:

C2H5OH C2H4 + H2O

Structures for reactants and products are shown below.

Calculate the enthalpy of the reaction using the average bond enthalpies in

the table below.

Bond Average bond enthalpy/ kJmol-1

O – H + 464

C – H + 414

C – C + 347

C – O + 352

C = C + 598

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2.4 Describe the energy change during the process of bond breaking and bond

formation.

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STRAND 3: AQUEOUS EQUILIBRIUM SYSTEMS

3.1a

A solution of acetic acid, CH3COOH, was prepared and its concentration was found to be 0.017 mol L-1. Calculate the pH of this acetic acid solution at equilibrium, given that

Ka (CH3COOH) = 1.74 x 10-5. Show all working.

3.1b

Some crystals of sodium acetate, CH3COONa, accidently spilt into the prepared acetic acid, changing the pH of the solution. This is an example of a common ion effect.

Define common ion effect.

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3.2a

Use the information below to answer questions 3.2a and 3.2b. Ammonia is prepared according to the following equilibrium reaction: N2(g) + 3H2(g) 2NH3(g) ∆H = -90kJ mol-1

Write the equilibrium constant expression for the reaction.

3.2b State the effect on the equilibrium constant K, if the temperature for the reaction was increased.

3.3 A solution is a uniform mixture of a solute and a solvent whose nature

and concentrations affects the properties of the whole solution.

Discuss the:

nature of the species in a solution and how it affects the conductivity

of the solution as an electrolyte; and

relative concentrations of the species in solution and how it affects

the overall pH (acidity and alkalinity).

NB: Provide examples with relevant chemical equations to support your

discussion.

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3.3 (cont.)

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STRAND 4: OXIDATION-REDUCTION REACTIONS

4.1a

Use the information below to answer questions 4.1a – 4.1e.

A simple galvanic cell is set up in the diagram below.

(Source: www.smartlearner.mobi)

What is a galvanic cell?

4.1b Name one feature on the diagram that identifies the set up as a galvanic cell.

4.1c How is this set up different from that of an electrolytic cell?

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4.1d

The electrode potentials values are as follows:

Eo for Cu2+(aq) / Cu(s) = +0.34V

Eo for Al3+(aq) / Al(s) = -1.66V

Write the cell notation for the galvanic cell above, using the IUPAC notation.

4.1e Calculate the Eo of the galvanic cell, and determine if the cell is spontaneous.

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STRAND 5: ORGANIC CHEMISTRY

5.1a

Use the information below to answer questions 5.1a - 5.1e

The enantiomer (CH3)2 CH – CHBr – CH3 undergoes different types of reactions as shown in the diagram below.

Excess NH3 Aqueous NaOH

Compound C

Compound D

Compound A

Compound E

What is an enantiomer?

5.1b In reaction Y, two organic compounds are produced. Compound A is the major product. Draw the structure, and give the IUPAC name of the minor Compound B.

Structure:

Name: _______________________________

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Reaction Y Alcoholic KOH

+ Compound B

(CH3)2CH

Reaction X acidified KMnO4

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5.1c Identify reaction Y.

5.1d Name reaction X and draw the structure of Compound E.

Name: ________________________________

Structure:

5.1e Give the IUPAC name for Compound D.

5.1f In a separate reaction, a structural isomer of Compound E with molecular formula C5H10O, and believed to be an aldehyde, was heated with acidified potassium permanganate (KMNO4) solution. List two observations that would be made.

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5.2 Alcohols are able to react in many different ways, producing compounds widely used in household, industrial and commercial items. Discuss one reaction of alcohols, and the reactions of their products that accounts for their wide use in real life. Your answer should include the:

i. name of the reaction; ii. chemical names of the products; iii. chemical formula/formulae; and iv. balanced chemical equations where applicable.

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THE END