AQA Jun 2016 Paper 5 Q6

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do not write outside the box in the contact process sulfur dioxide reacts with oxygen to form sulfur trioxide as shown in the equation so g o g so g table shows some thermodynamic data table so g o g so g hf kj mol s j k mol a use data from table to calculate the standard enthalpy change for this reaction marks b use data from table to calculate the standard entropy change for this reaction marks c state what the sign of the entropy change in your answer to part b indicates about the product of this reaction relative to the reactants mark wmp jun chem do not write outside the box d use your answers to parts a and b to calculate a value for the free energy change for this reaction at c if you were unable to calculate h in part a assume a value of kj mol if you were unable to calculate s in part b assume a value of j k mol these are not the correct values marks e use your answer to part d to explain whether the reaction is feasible at c mark f vanadium v oxide acts as a heterogeneous catalyst in the contact process f i state what is meant by the term heterogeneous mark f ii write two equations that show how this catalyst is involved in the contact process marks turn over wmp jun chem do not write outside the box f iii suggest why the vanadium v oxide is used in small pellet form rather than as large lumps mark f iv state why the reactants should be purified before they come into contact with the vanadium v oxide mark wmp jun chem turn over for the next question do not write on this page answer in the spaces provided turn over wmp jun chem

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