CIE Nov 2013 v2 Paper 4 Q5

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Examiners For Use 10 Super-absorbent polymers have the ability to absorb 200-300 times their own mass of water. They are classi ed as hydrogels and they are widely used in personal disposable hygiene products such as babies nappies (diapers). These polymers are commonly made by the polymerisation of compound K mixed with sodium hydroxide in the presence of an initiator. CH2 CO2H (a) (i) Explain what is meant by the term polymerisation.(ii) What type of polymerisation is involved in the formation of hydrogels?(iii) Describe the changes in chemical bonding that occur during the polymerisation of K.[3] (b) Acrylic acid is the common name for compound K. Suggest the systematic (chemical) name of K.[1] (c) (i) Draw the structure of at least two repeat units of the polymer formed by the above method from acrylic acid, K, when mixed with NaOH. (ii) The CCC bond angle in compound K changes when the polymer is formed. State and explain how the CCC bond angle differs between a molecule of K and the polymer. angle changes fromtoexplanation[4]UCLES 2013 9701/42/O/N/13<br /> (d) (i) Draw a detailed diagram of a portion of the polymer you have drawn in (c)(i) to explain how it can absorb a large volume of water. 11 Examiners For Use (ii) A student added 0.10 g of the polymer to 10 cm3 of aqueous copper(II) sulfate solution. Predict, with a reason, what you expect to observe.[4] (e) Compound L, CH2=CHCONH2, can also be polymerised to form a super-absorbent polymer. (i) Name the two functional groups in compound L.Compound K can be converted into compound L by the following two-step route. H2C H C step 1 H C step 2 CO2H H2C CO2 NH4 H2C H C CONH2 (ii) Suggest a reagent for step 1.(iii) What other product is formed in step 2?(iv) State the reagents and conditions necessary to re-form K from L.[5]UCLES 2013 9701/42/O/N/13 [Total: 17] [Turn over<br />

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