CIE Jun 2013 v1 Paper 4 Q8

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Examiners For Use 14 In recent years there has been a lot of interest in polymers in the form of gels that absorb aqueous materials. One of the largest uses of these polymers is in disposable nappies (diapers). The gel which is used in this case is a polymer of propenoic acid. OH propenoic acid (a) (i) Draw a section of the polymer of propenoic acid showing two repeat units. (ii) By what type of chemical reaction is this polymer formed?(iii) By what type of bonding is water held on the polymer?[3] (b) For some disposable nappies (diapers), the monomer is a mixture of propenoic acid and sodium propenoate. The properties of the polymer are in uenced by the proportion of sodium salt in the monomer mixture. (i) Suggest and explain how the difference in the structure of this polymer compared to one formed only from propenoic acid might affect the water absorbing properties of the polymer.(ii) Suggest a property the polymer should have in order to be used in disposable products.[3]UCLES 2013 9701/41/M/J/13<br /> Examiners For Use 15 (c) A variation on the gel used for disposable nappies (diapers) containing more sodium propenoate has been used to treat soils contaminated by heavy metals such as lead (Pb2+) and cadmium (Cd2+). Suggest why the gel is effective.[2] (d) Another variation on this type of polymer is used in hair gels. In these, the polymer chains are cross-linked by a compound known as pentaerythritol. HO HO OH OH pentaerythritol (i) By what type of chemical reaction are the cross-links in this polymer formed?(ii) It is important that the gel should be easily washed out of hair. What is it about the structure of the polymer that allows this to happen?[2] [Total: 10]UCLES 2013 9701/41/M/J/13 [Turn over<br />

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