AQA Jun 2012 Paper 4 Q1

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section a answer all questions in the spaces provided do not write outside the box a a mixture of mol of hydrogen and mol of gaseous iodine was sealed in a container of volume v dm the mixture was left to reach equilibrium as shown by the following equation h g l g hl g at a given temperature the equilibrium mixture contained mol of hydrogen iodide a i calculate the amounts in moles of hydrogen and of iodine in the equilibrium mixture moles of hydrogen moles of iodine marks a ii write an expression for the equilibrium constant kc for this equilibrium mark a iii kc for this equilibrium has no units state why the units cancel in the expression for kc mark a iv a different mixture of hydrogen iodine and hydrogen iodide was left to reach equilibrium at the same temperature in a container of the same volume this second equilibrium mixture contained mol of hydrogen mol of iodine and mol of hydrogen iodide calculate a value for kc for this equilibrium at this temperature marks extra space wmp jun chem do not write outside the box b this question concerns changes made to the four equilibria shown in parts b i to b iv in each case use the information in the table to help you choose from the letters a to e the best description of what happens as a result of the change described write your answer in the box each letter may be used once more than once or not at all position of equilibrium value of equilibrium constant kc remains the same moves to the right moves to the left moves to the right moves to the left same same same different different b i change increase the temperature of the equilibrium mixture at constant pressure h g l g hl g h kj mol b ii change increase the total pressure of the equilibrium mixture at constant temperature h g n g nh g h kj mol mark b iii change add a catalyst to the equilibrium mixture at constant temperature co g h o g co g h g h kj mol b iv change add chlorine to the equilibrium mixture at constant temperature pcl g pcl g cl g h kj mol mark mark mark turn over wmp jun chem

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