Chemistry 9701 · AS & A Level · States of matter

States of matter — practice question

An alkene, a carboxylic acid and a ketone, each with roughly the same volatility, are combined in one mixture. The mixture is then examined by gas chromatography, and the chromatogram obtained is shown. The separation of the three substances depends on how soluble they are relative to one another in the liquid stationary phase. The liquid stationary phase is an alkane.
(a(i))[2]

Complete the table to show which compound in the mixture is responsible for each peak J, K and L. Explain your answer using the intermolecular forces of each compound.

(a(ii))[1]

The area beneath each peak is proportional to the mass of the corresponding compound. Calculate the percentage by mass in the original mixture of the compound responsible for peak K.

(b(i))[1]

Write an equation showing how $\text{AlCl}_3$ generates the electrophile needed in this reaction.

(b(ii))[4]

Draw the mechanism for the reaction between this electrophile and benzene to make chlorobenzene. Include all relevant curly arrows and charges.

(b(iii))[1]

Write an equation showing how the catalyst is regenerated.

(c(i))[1]

Explain what is meant by a homogeneous catalyst.

(c(ii))[1]

Complete the table by placing one tick $(\checkmark)$ in each row to show whether the catalyst acts homogeneously or heterogeneously in each reaction: $\mathrm{Rh}$ in the removal of $\text{NO}_2$ from car exhaust gases; $\mathrm{Fe}^{3+}$ in the $\text{I}^- / \text{S}_2\text{O}_8^{2-}$ reaction.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: Peak J is the carboxylic acid

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