AQA Jan 2011 Paper 4 Q3

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do not write outside the box synthesis gas is a mixture of carbon monoxide and hydrogen methanol can be manufactured from synthesis gas in a reversible reaction as shown by the following equation co g h g ch oh g h kj mol a a sample of synthesis gas containing mol of carbon monoxide and mol of hydrogen was sealed together with a catalyst in a container of volume dm when equilibrium was established at temperature t the equilibrium mixture contained mol of carbon monoxide calculate the amount in moles of methanol and the amount in moles of hydrogen in the equilibrium mixture methanol hydrogen marks b a different sample of synthesis gas was allowed to reach equilibrium in a similar container of volume dm at temperature t at equilibrium the mixture contained mol of carbon monoxide mol of hydrogen and mol of methanol b i write an expression for the equilibrium constant kc for this reaction mark b ii calculate a value for kc for the reaction at temperature t and state its units calculation units marks b iii state the effect if any on the value of kc of adding more hydrogen to the equilibrium mixture mark wmp jan chem do not write outside the box c the temperature of the mixture in part b was changed to t and the mixture was left to reach a new equilibrium position at this new temperature the equilibrium concentration of methanol had increased deduce which of t or t is the higher temperature and explain your answer higher temperature explanation marks d the following reaction has been suggested as an alternative method for the production of methanol co g h g ch oh g h o g the hydrogen used in this method is obtained from the electrolysis of water suggest one possible environmental disadvantage of the production of hydrogen by electrolysis mark e one industrial use of methanol is in the production of biodiesel from vegetable oils such as ch oocc h choocc h ch oocc h give the formula of one compound in biodiesel that is formed by the reaction of methanol with the vegetable oil shown above mark turn over wmp jan chem

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