Chemistry 9701 · AS & A Level · Hydrocarbons

Hydrocarbons — practice question

Bromine reacts with both alkanes and alkenes.
(a)[2]

Explain how bromine can be used to tell an alkene from an alkane, and why this works.

(b(i))[1]

State the essential conditions for ethane to react with bromine.

(b(ii))[2]

Give the full name of the mechanism for this reaction.

(b(iii))[1]

Give the equation for a termination step that could occur and that forms a hydrocarbon.

(b(iv))[1]

Give one propagation-step equation involved in forming dibromoethane from bromoethane in this reaction.

(c(i))[2]

Give the full name of the mechanism for the reaction between ethene and bromine.

(c(ii))[4]

Complete the diagram to show this mechanism. Include all relevant charges, partial charges, curly arrows and lone pairs.

(d)[2]

Chloroethene can be polymerised to make the polymer known as PVC. Draw the structure of PVC and include three repeat units.

(e(i))[2]

Give the reagent and conditions required for reaction 1.

(e(ii))[1]

Give the skeletal formula for product P.

(e(iii))[2]

Give the displayed formula and name for product Q.

Worked solution & mark scheme

This 20-mark question has a full step-by-step worked solution and mark scheme. One marking point: Decolourisation of bromine by an alkene at room temperature

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