AQA Jan 2013 Paper 4 Q3

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do not write outside the box a esters are produced by the reaction of alcohols with other esters and by the reaction of alcohols with carboxylic acids the esters which make up biodiesel are produced industrially from the esters in vegetable oils a i complete the equation for this formation of biodiesel ch oocc h choocc h ch oocc h c h cooch c h cooch marks c h cooch a ii write an equation for the complete combustion of c h cooch marks b the ester commonly known as diethyl malonate dem occurs in strawberries and grapes it can be prepared from acid a according to the following equilibrium h c cooh cooh c h oh h c h o cooc h cooc h dem b i a mixture of mol of a and mol of ethanol was left to reach equilibrium in an inert solvent in the presence of a small amount of concentrated sulfuric acid the equilibrium mixture formed contained mol of dem in a total volume v dm of solution calculate the amount in moles of a of ethanol and of water in this equilibrium mixture moles of a moles of ethanol moles of water marks wmp jan chem do not write outside the box b ii the total volume of the mixture in part b i was doubled by the addition of more of the inert solvent state and explain the effect of this addition on the equilibrium yield of dem effect explanation marks b iii using a to represent the acid and dem to represent the ester write an expression for the equilibrium constant kc for the reaction mark b iv in a second experiment the equilibrium mixture was found to contain mol of a mol of ethanol mol of dem and mol of water calculate a value of kc for the reaction and deduce its units calculation units marks turn over wmp jan chem there are no questions printed on this page do not write on this page answer in the spaces provided wmp jan chem

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