12 organic chemistry

7/28/2019 12 Organic chemistry

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Classified ChemistryEdexel 4CHO/1C_Topic_12

Topic 12

12 - Organic Chemistry Mostafa Barakat (0100 165 44 62)

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1) Sample Assessment Materials 2011 Q (8)

8. The alkenes are a homologous series of unsaturated hydrocarbons.

(a) (i) Place a cross () in the two boxes that indicate which statements aboutmembers of a homologous series are correct.

A They have similar chemical properties

B They have the same displayed formula

C They have the same general formula

D They have the same physical properties

E They have the same relative formulamasses

(2)

(ii) State the meaning of the term unsaturated.

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

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

(1)

(b) Alkenes react with bromine water. Ethene is the simplest alkene.(i) Bromine water is added to ethene. State the colours of the reaction mixtureat the start and the finish.

Colour at start ....................................................................................................

Colour at finish ...................................................................................................

(2)

(ii) Complete the equation by drawing the displayed formula of the product.

(1)


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(c) Isomers are compounds that have the same molecular formula butdifferent displayed formulae.

Draw the displayed formulae of two isomers that have the molecular formula C4H8.

(2)

2) June 2011 Q (4)

4 Here are some statements about the compound ethene.

ethene has the displayed formula

ethene is a gas at room temperature

ethene burns with a smoky flame

ethene is unsaturated

ethene is insoluble in water

ethene can be prepared from ethanol

ethene is used to make the polymer poly(ethene)

(a) (i) State why ethene is described as unsaturated.

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

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

(1)

(ii) Describe a chemical test to show that ethene is an alkene.

Test ....................................................................................................................

Result ................................................................................................................


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(2)

(b) (i) Complete the following equation that represents the preparation ofethene from ethanol.

(1)

2 5 2 4.................C H OH C H +

(ii) What is the name given to this type of reaction?

(1)

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

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

(c) Complete the equation to show the formation of poly(ethene) from ethene.

(2)

3) June 2011 Q (8)

8A teacher explained the different types of formula used in organic chemistry,using ethene as an example

(a) Use this example to help you write the formulae described below.(i) The empirical formula of methane

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

(1)

(ii) The molecular formula of ethane

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


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(1)

(iii) The structural formula of propane

(1)

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(iv) The displayed formula of butane

(1)

(c) All the compounds in part (a) are hydrocarbons. They can undergocomplete combustion when burned in oxygen to form carbon dioxide andwater.

(i) Write a chemical equation for the complete combustion of propane (C3H8).

(2)

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

(ii) Identify one solid product and one gaseous product that could form duringthe incomplete combustion of propane.

(2)Solid product

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

Gaseous product

............................................................................................................................(d) The displayed formula of pentane is

Draw a displayed formula for each of the two isomers of pentane.

(2)Isomer 1 Isomer 2

(e) When methane reacts with bromine, one of the products is hydrogen

bromide.(i) State a condition needed for this reaction.


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

(1)(ii) Name the organic product of the reaction.

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

(1)(iii) Write a chemical equation for the reaction.

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

(2)

4) Jan 2012 Q (5)

5 These are the displayed formulae of six organic compounds.

(a) Use the letters above to select

(i) the compound that is not a hydrocarbon.

(1)

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

(ii) one compound with the empirical formula CH2(1)

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

(iii) one compound that can form a polymer.(1)

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

(b) Describe a test that will distinguish between compounds Q and T, andstate the observation made with compound T.

(2)

Test ....................................................................................................................

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Observation with compound T ...........................................................................

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(c) Draw the displayed formula of an alkene containing four carbon atoms.(1)

(d) Three of the compounds belong to the alkane homologous series.

All the alkanes in this homologous series have the same general formula.

(i) What is the general formula of the alkanes?

(1)

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

(ii) State two other features of a homologous series.

(2)

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

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

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

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(e) The displayed formulae below represent isomers.

Explain what isomers are.(2)

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5) June 2012 Q (7)

7 Decane is a hydrocarbon found in crude oil the diagram shows the structureof a decane molecule.

(a) (i) Explain why decane is described as a hydrocarbon.

(2)

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

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

(ii) Give the molecular formula for decane.(1)

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

(b) Decane and ethene, C2H4, are produced during the cracking of eicosane,C20H42

Ethene is used to make poly(ethene).

(i) What is the name given to this type of polymerisation?


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(1)

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

(ii) Use the diagram to state two changes that occur during the formation ofpoly(ethene).

(2)............................................................................................................................

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

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(c) Explain why cracking is an important process in the oil industry.(4)

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6) Sample Assessment 2013 Q (5)

5 Fractional distillation is an important process in the oil industry.

In this process, the crude oil is separated into a number of fractions.Each fraction is a mixture of hydrocarbons.

The diagram shows the column used for fractional distillation.


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(a) What is meant by the term hydrocarbon?(2)

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

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

(b) Bitumen, diesel, gasoline and refinery gases are three of the fractionsobtained from crude oil.

(i) Which one of these three fractions has the lowest boiling point?

(1)............................................................................................................................

(ii) Which one of these three fractions is the most viscous?(1)

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

(c) Explain how the separation of crude oil into fractions takes place in thefractionating column.

(4)

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............................................................................................................................7) Sample Assessment 2013 Q (6)


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6 (a) Isomers are compounds that have the same molecular formula butdifferent displayed formulae

The molecular formula C4H8 represents several isomers.

The displayed formulae and names for two of these isomers are

(i) Draw the displayed formula and give the name for another alkene with the

molecular formula C4H8

(2)

Name .........................................................................

(ii) The displayed formula of another isomer of C4H8 is

The general formula of cyclobutane is also CnH2n

State why cyclobutane is not an alkene.

(1)

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

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


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(iii) Cyclobutane can be distinguished from but-1-ene by addingbromine water and shaking. Bromine water is orange.

State what you would see when bromine water is shaken separatelywith each

compound.(2)

Observation with cyclobutane

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

Observation with but-1-ene

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

(b) Cracking is used to break long alkane molecules into shorteralkanes and alkenes.

Explain why this process is of such importance in the petrochemicalindustry.

(2)

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(c) Cracking can be carried out in the laboratory by passing thevapour of an alkane over a heated catalyst using the apparatusshown.


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When decane (C10H22) is cracked, a shorter chain alkane and ethene (C2H4)can be produced.

(i) Write a chemical equation for the cracking of decane.

(2)

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

(ii) The alkane produced can be used as a fuel for cars.

When this fuel is burned in a car engine, some incompletecombustion occurs.

This produces carbon monoxide, which is dangerous to humans.

Explain why carbon monoxide is dangerous to humans.

(2)

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

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

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8) Jan 2013 Q (5)

5 The table shows the displayed formulae of three unsaturated hydrocarbons.

(a) Explain the meaning of the term hydrocarbon.

(2)

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

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

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

(b) Explain the meaning of the term unsaturated.

(1)

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(c) Compounds A, B and C belong to the same homologous series. Onecharacteristic of the compounds in a homologous series is that they have thesame general formula.

(i) State the name of this homologous series.

(1)


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

(ii) State the general formula of this homologous series.

(1)

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

(iii) State two other characteristics of the compounds in a homologous series.

(2)

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

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

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

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

(d) Compound C has several isomers.

(i) What is the name of compound C?

(1)

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

(ii) What is the molecular formula of compound C?

(1)

............................................................................................................................(iii) Explain the meaning of the term isomers.

(2)

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

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

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(iv) Draw the displayed formula of an isomer of compound C.

(1)


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(e) Bromine water can be used to distinguish compound A from ethane.

(i) Complete the sentence to show the colour change when compound A is

bubbled through bromine water.

(1)

Bromine water changes from orange to ........................................................... .

(ii) Complete the chemical equation for the reaction between compound A and

bromine water.

(1)

C2H4 + Br2 ..............................................................

9) Jan 2013 Q (10)

10A teacher discussed with her students whether the boiling points of organiccompounds are related to the size of their molecules.

The students suggested measuring the boiling points of some organiccompounds using this apparatus.

(a) The teacher said that their suggested method was too dangerous.

She recommended using the apparatus shown below instead.


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Suggest one reason why this apparatus is better than the students

suggestion.(1)

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

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

(b) The students used the apparatus recommended by the teacher tomeasure the boiling points of five alcohols.

Their results are shown in the table.

(i) Plot a graph of the data in the table on the grid.

Draw a straight line of best fit through the points.

(3)


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(ii) Describe the relationship shown by your graph.

(1)

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

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(iii) Use your graph to predict the boiling point of the alcohol that has a relative

formula mass of 74.

(1)

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

(iv) Which of the alcohols A, B, C, D orE is the least volatile?

(1)


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12 organic chemistry

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