Chemistry 9701 · AS & A Level · Hydrocarbons

Hydrocarbons — practice question

(a)[4]

Describe the arrangement of atoms in a benzene molecule, $\text{C}_6\text{H}_6$. Your response should cover the molecular shape, the relative C-C bond lengths, bond angles, carbon hybridisation, and the orbital overlap responsible for each bond type present.

(b(i))[2]

Step 1 is benzene reacting with $\text{NO}_2^+$ ions. Finish the mechanism and draw the intermediate for step 1. Include every relevant charge and the curly arrows needed to show electron-pair movement.

(b(ii))[1]

State the mechanism name in (b)(i).

(b)

Benzene may be used as the starting material to make phenylamine in a two-step synthesis.

(b(iii))[2]

Identify the reagents required to make $\text{NO}_2^+$ ions. Write an equation that shows how these reagents generate $\text{NO}_2^+$ ions.

(b(iv))[2]

Give the reagents and conditions needed to produce phenylamine from nitrobenzene in step 2.

(c)

Phenylamine is treated with $\text{Br}_2\text{(aq)}$.

(c(i))[1]

Write an equation for this reaction. Structural or displayed formulae may be used.

(c(ii))[1]

Name the organic product formed in this reaction.

(c(iii))[1]

Describe two observations visible when phenylamine reacts with $\text{Br}_2\text{(aq)}$.

(d)[3]

Describe the relative basicities of ammonia, ethylamine and phenylamine, beginning with the least basic. Explain your answer using their structures.

(e)

1,3-diaminopropane, $\text{H}_2\text{NCH}_2\text{CH}_2\text{CH}_2\text{NH}_2$, can be used to produce polyamides.

(e(i))[1]

Identify one compound that could react with 1,3-diaminopropane to make a polyamide.

(e(ii))[2]

Draw a section of the polymer chain made from 1,3-diaminopropane and the compound you selected in (e)(i). Your answer should contain four monomer residues (two of each monomer type); show the amide link fully displayed; identify one repeat unit of this polymer clearly.

Worked solution & mark scheme

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