Chemistry 9701 · AS & A Level · Polymerisation

Polymerisation — practice question

Interest in polymers that form gels and absorb aqueous materials has risen sharply in recent years. One of the biggest applications of these polymers is in disposable nappies (diapers). In this example, the gel is a polymer of propenoic acid.
(a(i))

Draw a part of the propenoic acid polymer that shows two repeat units.

(a(ii))

What type of chemical reaction produces this polymer?

(a(iii))[3]

What type of bonding holds the water on the polymer?

(b(i))

Suggest and explain how the structural difference in this polymer, compared with one formed only from propenoic acid, could change its water absorbing properties.

(b(ii))[3]

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

(c)[2]

A modified version of the gel used in disposable nappies (diapers), containing more sodium propenoate, has been used to clean soils polluted 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 formed?

(d(ii))[2]

The gel must wash out of hair easily. What is it about the polymer's structure that 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: “Displayed repeat unit drawn correctly with $\text{CO}_2\text{H}$ side groups” …

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