OCR A Jun 2016 Paper 4 Q4

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This question is about the preparation, properties and uses of lactic acid. 10 OH OH lactic acid (a) What is the systematic name of lactic acid?[1] (b) Lactic acid can be produced by chemical synthesis or by the fermentation of sugars using bacteria. Describe one important difference between lactic acid manufactured by chemical synthesis and lactic acid manufactured by the fermentation of sugars.[1] (c) When heated strongly, lactic acid forms a cyclic diester. The diester has the molecular formula, C6H8O4. Draw the structure of the cyclic diester. [1]OCR 2016<br /> 11 PLA breaks down into smaller molecules after one or two weeks. (d) Poly(lactic acid), PLA, is used to make dissolvable stitches (for holding wounds together). (i) Draw the structure of one repeat unit in PLA. (ii) Explain how PLA breaks down and why the stitches dissolve. In your answer you should use the appropriate technical terms spelled correctly. [1][3] [Total: 7]OCR 2016 Turn over<br />

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