Chemistry 9701 · AS & A Level · Hydrocarbons

Hydrocarbons — practice question

Hexane, $\text{C}_6\text{H}_{14}$, is a colourless liquid. There are equal quantities of hexane in two test-tubes. $1\ \text{cm}^3$ of bromine, $\text{Br}_2\text{(aq)}$, is added to each test-tube. One tube is left in the dark, while the other is placed in sunlight. The table shows what each test-tube looks like after one hour.
(a)[2]

The test-tube kept in the dark is maintained at a low temperature and is not exposed to ultraviolet light. Explain the observations for the test-tube kept in the dark.

(b(i))[1]

State the name of the mechanism by which the reaction occurs.

(b(ii))[1]

Give an equation that shows a propagation step in this reaction in which hexane forms $\cdot\text{C}_6\text{H}_{13}$.

(b(iii))[1]

Give an equation that shows a propagation step in this reaction which forms 1-bromohexane.

(b(iv))[1]

Give an equation that shows a termination step in this reaction which produces 1-bromohexane.

(c(i))[1]

Draw the structural formula for A.

(c(ii))[2]

State the conditions required for this reaction of A.

(d(i))[1]

Name the type of reaction taking place.

(d(ii))[2]

Using $\sigma$ and $\pi$ bonds, describe the similarities and differences between the type of carbon-carbon bonds in B and the type of carbon-carbon bonds in hexane.

Worked solution & mark scheme

This 12-mark question has a full step-by-step worked solution and mark scheme. One marking point: No reaction because there is not enough energy

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