Chemistry 9701 · AS & A Level · Polymerisation

Polymerisation — practice question

(a(i))[3]

Complete the equations to represent the two kinds of polymerisation. Draw one repeat unit for each polymer and include any extra products. Addition polymerisation: $n\,\text{CH}_2{=}\text{CHCH}_3(g) \rightarrow$ … Condensation polymerisation: $n\,\text{HO}_2\text{CCH}_2\text{CO}_2\text{H}(s) + n\,\text{HOCH}_2\text{CH}_2\text{OH}(l) \rightarrow$ …

(a(ii))[2]

State the likely sign of the entropy change, $\Delta S^\circ$, for each of the two polymerisation types, and explain your answers: • $\Delta S^\circ$ for addition polymerisation • $\Delta S^\circ$ for condensation polymerisation

(b(i))[1]

Complete the equation by entering the products in the box: $\text{R-CO}_2\text{H} + \text{H}_2\text{N-R'} \rightarrow$ … $+$ …

(b(ii))[2]

Use your answer to (i) to determine which bonds are broken and which are formed in the reaction between a carboxylic acid and an amine: • bonds that are broken • bonds that are formed

(b(iii))[2]

Use bond energy values from the Data Booklet to work out the enthalpy change, $\Delta H^\circ$, when one mole of amide bonds is produced in the reaction in (i).

(c)[2]

Amide bonds may also be made by reacting acyl chlorides with amines. The enthalpy change for this process, $\Delta H^\circ$, is $-6.00\,\text{kJ mol}^{-1}$. Calculate the minimum entropy change, $\Delta S^\circ$, required for this reaction to be spontaneous (feasible) at $298\,\text{K}$.

(d(i))[1]

The monomers of Kevlar, benzene-1,4-dioic acid and 1,4-diaminobenzene, can be made as shown. State the reagents and conditions required for reaction 1.

(d(ii))[2]

The monomers of Kevlar, benzene-1,4-dioic acid and 1,4-diaminobenzene, can be made as shown. State the reagents and conditions required for reaction 2.

(e)[2]

Kevlar is both strong and rigid. Complete the table by identifying two intermolecular forces and the groups involved that account for these properties of Kevlar.

Worked solution & mark scheme

This 17-mark question has a full step-by-step worked solution and mark scheme. One marking point: Correct polymer structures for initiation, propagation and termination

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