AQA Jan 2011 Paper 4 Q2

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do not write outside the box this question is about the ph of several solutions give all values of ph to decimal places a i write an expression for ph mark a ii calculate the ph of mol dm hydrochloric acid mark a iii calculate the ph of the solution formed when cm of mol dm hydrochloric acid are added to cm of water marks b the acid dissociation constant ka for the weak acid hx has the value x mol dm at c a solution of hx has a ph of calculate the concentration of hx in the solution marks question continues on the next page turn over wmp jan chem do not write outside the box c explain why the ph of an acidic buffer solution remains almost constant despite the addition of a small amount of sodium hydroxide marks d the acid dissociation constant ka for the weak acid hy has the value x mol dm at c a buffer solution was prepared by dissolving mol of the salt nay in cm of a mol dm solution of the weak acid hy d i calculate the ph of this buffer solution marks wmp jan chem do not write outside the box d ii a x mol sample of sodium hydroxide was added to this buffer solution calculate the ph of the buffer solution after the sodium hydroxide was added marks turn over for the next question turn over wmp jan chem

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