OCR A Jun 2010 Paper 4 Q2

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2 A student was researching the development of polymers and discovered three polyesters, PET, PEN and PGA, that are used in the manufacture of plastic bottles. (a) The student discovered that the first polyester developed was Terylene which is also known as poly(ethylene terephthalate) or PET. PET can be made by reacting benzene-1,4-dicarboxylic acid with ethane-1,2-diol. (i) Draw the displayed formula of the repeat unit in PET. (ii) The industrial manufacture of PET involves two main stages. The first stage, known as pre-polymerisation, forms compound F with molecular formula C12H14O6. Draw the structure of compound F. [2] (b) PEN is a new kind of polyester. PEN is rigid at high temperature whereas PET readily softens. The repeat unit of PEN is shown below. [1] PEN (i) What is the empirical formula of the repeat unit in PEN?[1]OCR 2010<br /> (ii) Draw the structures of two monomers that could be used to make PEN. (cid:4) (c) Polyglycolic acid, PGA, is a polymer that is being developed as an inner coating for PET bottles. [2] A short section of PGA is shown below. PGA (i) Compared with other synthetic polymers, PGA can be easily hydrolysed. Draw the skeletal formula of the organic product formed from the complete hydrolysis of PGA by NaOH(aq). [2] (ii) Explain why scientists now think that polymers such as PGA are better for the environment than hydrocarbon-based polymers. In your answer, you should use appropriate technical terms, spelt correctly.[1]OCR 2010 [Total: 9] Turn over<br />

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