Identify the two functional groups in the monomer from which this polymer is manufactured.

An expanded form of the plastic is often used in packaging. Describe how this is manufactured.

Discuss two advantages and one disadvantage of using the expanded form as a packaging material.

Two advantages:

One disadvantage:

alkenyl/C=C and phenyl/–\({{\text{C}}_{\text{6}}}{{\text{H}}_5}\);

Accept alkene and benzene ring/aromatic ring/arene but not benzene.

pentane/volatile hydrocarbon added (during polymerization process);

heating causes pentane/volatile hydrocarbon to evaporate/vaporize/produce bubbles of gas (expanding the polystyrene);

Accept other suitable identified blowing agents such as carbon dioxide.

Advantages:

Any two for [2 max]:

low/reduced density;

Accept “small mass”.

Do not accept “light”.

can be shaped (around object);

good shock absorber;

insulator;

Disadvantage:

Award [1] for disadvantage:

disposal takes up a lot of space (in landfill);

Accept “non-biodegradable/polluting/hazardous to wildlife”.

Some candidates identified two functional groups in the monomer. 

About half of the candidates described how the expanded form of the plastic could be manufactured.

Most candidates were able to score one or two marks. “Good shock absorber” was a popular answer. Candidates should be encouraged to use precise terminology such as “has low density” instead of “light”.