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CAIE A-Level Chemistry AS 14.1 Alkanes Questions

Practise alkane reactions through combustion equations, cracking products, radical substitution steps, unreactivity explanations and exhaust pollutant removal.

Syllabus
2028–2030
Course
Chemistry 9701
Level
AS

Exam points

  • write balanced alkane combustion equations and link products to oxygen supply
  • complete initiation, propagation and termination equations for halogen substitution
  • use cracking and catalytic converter evidence to select products, catalysts and pollutants

Covered syllabus points

14.1.1—Preparation of alkanes14.1.2—Describe14.1.3—Mechanism: free-radical substitution14.1.4—Suggest how cracking can be used to obtain14.1.5—The general unreactivity of alkanes14.1.6—Combustion pollutants and catalysts

Question 1

[Maximum number: 1]

Different hydrocarbon mixtures produced from fractional distillation of crude oil have different uses.

State the compound that is heated with long-chain hydrocarbons to produce more useful smaller alkanes and alkenes.

Question 2

[Maximum number: 1]

Which reaction occurs when ethane and chlorine are mixed in diffused sunlight?

A

a free-radical substitution with hydrogen given off

B

a free-radical substitution with hydrogen chloride given off

C

a free-radical substitution with no gas given off

D

a nucleophilic substitution with hydrogen chloride given off

Question 3

[Maximum number: 1]

Which equation represents a reaction that proceeds through initiation, propagation and termination steps?

A

C4H10+Cl2→C4H9Cl+HCl\mathrm{C}_{4} \mathrm{H}_{10}+\mathrm{Cl}_{2} \rightarrow \mathrm{C}_{4} \mathrm{H}_{9} \mathrm{Cl}+\mathrm{HCl}

B

C5H11Br+NaOH→C5H11OH+NaBr\mathrm{C}_{5} \mathrm{H}_{11} \mathrm{Br}+\mathrm{NaOH} \rightarrow \mathrm{C}_{5} \mathrm{H}_{11} \mathrm{OH}+\mathrm{NaBr}

C

C6H12+H2O→C6H13OH\mathrm{C}_{6} \mathrm{H}_{12}+\mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{C}_{6} \mathrm{H}_{13} \mathrm{OH}

D

C6H13CHO+HCN→C6H13CH(OH)CN\mathrm{C}_{6} \mathrm{H}_{13} \mathrm{CHO}+\mathrm{HCN} \rightarrow \mathrm{C}_{6} \mathrm{H}_{13} \mathrm{CH}(\mathrm{OH}) \mathrm{CN}

Question 4

[Maximum number: 1]

The hydrocarbon C17H36\mathrm{C}_{17} \mathrm{H}_{36} can be cracked.
Which compound is the least likely to be produced in this reaction?

A

C3H8\mathrm{C}_{3} \mathrm{H}_{8}

B

C4H8\mathrm{C}_{4} \mathrm{H}_{8}

C

C8H16\mathrm{C}_{8} \mathrm{H}_{16}

D

C16H34\mathrm{C}_{16} \mathrm{H}_{34}

Question 5

[Maximum number: 2]

The alkanes are a homologous series of organic molecules. Alkanes are generally unreactive and are commonly used as fuels.

Give two reasons to explain the general unreactivity of alkanes.

1

2

Question 6

[Maximum number: 1]

A catalytic converter reduces the amount of pollutants in the fumes from a car exhaust.
Which row identifies a pollutant and shows how it is removed by the action of the catalyst?

pollutant

chemical removal

carbon dioxide

reduced to carbon

carbon monoxide

oxidised to carbon dioxide

oxides of nitrogen

oxidised to nitric acid

unburnt hydrocarbons

oxidised to carbon dioxide and hydrogen

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