A LevelChemistryCIETopic Questions14. Hydrocarbons14.2 Alkenes

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First teaching 2023

First exams 2025

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Alkenes (CIE A Level Chemistry)

Topic Questions

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11 mark

Ethene reacts with steam in the presence of sulfuric acid.

C2H4  +  H2O  rightwards arrow CH3CH2OH

What type of reaction is this?

  • Acid / Base

  • Addition

  • Hydrolysis

  • Substitution

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21 mark

When bromine reacts with propene in an organic solvent at room temperature, what is the mechanism by which the bromine attacks the propene?

  • Electrophilic addition

  • Electrophilic substitution

  • Nucleophilic addition

  • Nucleophilic substitution

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31 mark

A molecule of a polymer contained the sequence shown.

3-2-e-7

Which monomer could produce this polymer by addition polymerisation?

  • CHCl=CHCl

  • CH2=CHCl

  • CH3CCl=CHCl

  • CH3CCl=CH2

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11 mark

Limonene is an oil formed in the peel of citrus fruits.

3-2-cie-ial-chemistry-diagram-q1hard
Which product is formed when an excess of bromine, Br2 (l), reacts with limonene at room temperature in the dark?

  • 3-2-h-1a

  • 3-2-h-1b

  • 3-2-h-1c

  • 3-2-h-1d

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21 mark

Which isomer of C6H13OH gives the greatest number of different alkenes when it is dehydrated?

  • 3-2-h-2a

  • 3-2-h-2b

  • 3-2-h-2c

  • 3-2-h-2d

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31 mark

Acrylic acid is produced from propene, a gaseous product of oil refineries.

3-2-h-3Which statement about acrylic acid is not correct?

  • Both bond angles x and y are approximately 120°.

  • It decolourises aqueous bromine.

  • It gives an orange precipitate with 2,4-dinitrophenylhydrazine reagent.

  • It reacts with an alcohol to give an ester.

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41 mark

Which compound has an Mr of 84 and will react with HBr to give a product with an Mr of 164.9?

  • 3-2-h-5a

  • 3-2-h-5b

  • 3-2-h-5c

  • 3-2-h-5d

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51 mark

Alkane X has molecular formula C4H10.

X reacts with Cl2 (g) in the presence of sunlight to produce only two different monochloroalkanes, C4H9Cl. Both of these monochloroalkanes produce the same alkene Y, and no other organic products, when they are treated with hot ethanolic KOH.

What is produced when Y is treated with hot concentrated acidified KMnO4?

  • CO2 and CH3CH2CO2H

  • CO2 and CH3COCH3

  • HCO2H and CH3COCH3

  • CH3CO2H only

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61 mark

The following diagram represents the structure of a possible polymer.

3-2-h-7By which method might this polymer be made?

  • Polymerise ethene followed by hydration.

  • Polymerise ethene followed by oxidation with cold acidified KMnO4.

  • Polymerise 1,2-dichloroethene followed by hydrolysis.

  • Polymerise 1,2-dichloroethene followed by oxidation with cold acidified KMnO4.

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71 mark

Oxidation of an alkene Y gives a diol; further oxidation gives a diketone.

What could be Y?

  • CH3CH=C(CH3)2

  • (CH3)2CHCH=CH2

  • C6H5CH=CHC6H5

  • (C6H5)2C=CHCH3

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81 mark

In a preparation of ethene, ethanol is added a drop at a time to a heated reagent Y. To purify the ethene it is bubbled through a solution Z and then collected. 

What could reagent Y and solution Z be?

 

Reagent Y

Solution Z

A

B

C

D

Acidified K2Cr2O7

Concentrated H2SO4

Concentrated H2SO4

Ethanolic NaOH

Dilute NaOH

Dilute H2SO4

Dilute NaOH

Concentrated H2SO4

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11 mark

Which reaction would not give propene?

  • Adding excess hot concentrated sulfuric acid to propan-1-ol.

  • Adding warm aqueous sodium hydroxide to 2-bromopropane.

  • Adding warm ethanolic sodium hydroxide to 1-bromopropane.

  • Passing propan-2-ol vapour over heated aluminium oxide.

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21 mark

Ethene reacts with aqueous bromine to give two products, CH2BrCH2Br and CH2BrCH2OH. 

Which statement about these products is correct?

  • Both products are obtained in this reaction by electrophilic substitution.

  • Both products are obtained in this reaction by nucleophilic addition.

  • Both products can be hydrolysed to form the same organic compound.

  • Both products can form hydrogen bonds with water.

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31 mark

Pent-2-ene, CH3CH2CH=CHCH3, reacts in a similar way to ethene.

Pent-2-ene is reacted with cold, dilute, acidified manganate (VII) ions. 

What will be produced in the greatest amount?

  • CH3CH2CH(OH)CH(OH)CH3

  • CH3CH2COCOCH3

  • a mixture of CH3CH2CH(OH)CH2CH3 and CH3CH2CH2CH(OH)CH3

  • CH3CH2COOH and CH3COOH

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41 mark

Isomers X and Y both react with HBr.

3-2-m-6

A mixture of X and Y is reacted with HBr. 

Which three structures represent three different possible products of this reaction?

A

(CH3)2CHCBr3

(CH3)2CBrCHBr2

CH3CHBrCHBrCH3

B

(CH3)2CHCBr3

(CH3)2CBrCHBr2

CH3CBr2CHBrCH3

C

(CH3)2CBrCBr3

(CH3)2CHCBr3

CH3CBr2CHBrCH3

D

(CH3)2CBrCHBr2

CHBr2CBr(CH3)CH3

CH3CHBrCBr2CH3

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51 mark

What is the major product formed when compound Q is warmed with excess HBr?

3-2-m-10

  • 3-2-m-10a

  • 3-2-m-10b

  • 3-2-m-10c

  • 3-2-m-10d

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