Alkanes (Edexcel IGCSE Science): Exam Questions

Which of these formulae is that of an alkane?

The table shows the molecular formulae of six organic compounds, A, B, C, D, E and F.

i) Explain which homologous series compound B belongs to.

ii) Give the letter of the compound that has the same empirical formula as its molecular formula.

iii) Compound F exists as two isomers.

Explain what is meant by the term isomers.

Include the structures of the two isomers of compound F in your answer.

Describe how compound D can be obtained from crude oil using the industrial process of fractional distillation.

Compound C can be used to make a polymer.

i) State the type of polymer formed from compound C.

ii) Name the polymer formed from compound C.

iii) Draw the structure of this polymer.

Include the displayed formula of the repeat unit.

The table shows the displayed formulae of some organic compounds.

Which two are not classed as alkanes?

This question is about alkanes and alkenes.

i) Complete the boxes by giving the missing information about the alkane with the molecular formula C₂H₆

ii) Complete the chemical equation for the complete combustion of the alkane C₂H₆

...........C₂H₆ + ...........O₂ → ...........CO₂ + ...........H₂O

iii) Incomplete combustion occurs when the air supply is limited.

Give the names of two products of incomplete combustion.

An alkene with molecular formula C₄H₈ reacts with bromine to form a compound with molecular formula C₄H₈Br₂

i) What is the name of this type of reaction?

ii) Draw displayed formulae for two different alkenes with the molecular formula C₄H₈

iii) State the term used for compounds with the same molecular formula but different structural formulae.

The alkene C₃H₆ can be polymerised to form the polymer poly(propene).

i) Complete the equation for this polymerisation reaction.

ii) Two ways of disposing of polymers such as poly(propene) are:

• burying them in landfill sites
• burning them to release heat energy

Discuss the environmental problems caused by these two methods of disposal.

Ethane and bromine can react in the following reaction:

What name is given to this type of reaction?

Methane and bromine react to form bromomethane and hydrogen bromide.

What does this reaction occur in the presence of?

What is the correct chemical formula of butane?

There are three isomers with the molecular formula C₅H₁₂

One of these isomers is pentane.

The displayed formula for pentane is

i) State what is meant by the term isomers.

ii) Draw the displayed formula for another isomer of C₅H₁₂

Pentane reacts with bromine in the presence of ultraviolet radiation.

i) Complete the equation for this reaction.

C₅H₁₂ + Br₂ → .................... + ....................

ii) Give the name of this type of reaction.