AQA Jan 2010 Paper 5 Q3

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areas outside the box will not be scanned for marking hydrogen oxygen fuel cells can operate in acidic or in alkaline conditions but commercial cells use porous platinum electrodes in contact with concentrated aqueous potassium hydroxide the table below shows some standard electrode potentials measured in acidic and in alkaline conditions half equation o g h aq e h o l o g h o l e oh aq h aq e h g h o l e oh aq h g e v a state why the electrode potential for the standard hydrogen electrode is equal to v mark b use data from the table to calculate the e m f of a hydrogen oxygen fuel cell operating in alkaline conditions mark c write the conventional representation for an alkaline hydrogen oxygen fuel cell marks d use the appropriate half equations to construct an overall equation for the reaction that occurs when an alkaline hydrogen oxygen fuel cell operates show your working marks wmp jan chem areas outside the box will not be scanned for marking e give one reason other than cost why the platinum electrodes are made by coating a porous ceramic material with platinum rather than by using platinum rods mark f suggest why the e m f of a hydrogen oxygen fuel cell operating in acidic conditions is exactly the same as that of an alkaline fuel cell mark g other than its lack of pollution state briefly the main advantage of a fuel cell over a re chargeable cell such as the nickel cadmium cell when used to provide power for an electric motor that propels a vehicle mark h hydrogen oxygen fuel cells are sometimes regarded as a source of energy that is carbon neutral give one reason why this may not be true mark turn over for the next question turn over wmp jan chem

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