Chemistry 9701 · AS & A Level · Polymerisation

Polymerisation — practice question

Interest in polymers that absorb aqueous material has increased markedly in recent years. One major use is in disposable nappies (diapers). The gel used here is a polymer of propenoic acid.
(a(i))

Draw two repeat units of the propenoic acid polymer.

(a(ii))

By what type of chemical reaction does this polymer form?

(a(iii))[3]

By what type of bonding is water held on to the polymer?

(b(i))

Suggest and explain how the structural difference between this polymer and one formed only from propenoic acid might affect the polymer’s water absorbing properties.

(b(ii))[3]

Suggest a property the polymer must have if it is to be used in disposable products.

(c)[2]

A modified form of the gel used in disposable nappies (diapers), with more sodium propenoate, has been used to treat soils contaminated by heavy metals such as lead ($\text{Pb}^{2+}$) and cadmium ($\text{Cd}^{2+}$). Suggest why the gel is effective.

(d(i))

By what type of chemical reaction are the cross-links in this polymer made?

(d(ii))[2]

It is important that the gel can be washed out of hair easily. What feature of the polymer structure makes this possible?

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Accurate drawing of the polymer repeat unit” …

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