AQA Jun 2014 Paper 5 Q5

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table shows some standard electrode potential data do not write outside the box table e v zno s h o i e zn s oh aq fe aq e fe s o g h o i e oh aq hocl aq h aq e cl g h o i a give the conventional representation of the cell that is used to measure the standard electrode potential of iron as shown in table marks b with reference to electrons give the meaning of the term reducing agent mark c identify the weakest reducing agent from the species in table explain how you deduced your answer marks species explanation wmp jun chem do not write outside the box d when hocl acts as an oxidising agent one of the atoms in the molecule is reduced d i place a tick next to the atom that is reduced mark atom that is reduced tick cl d ii explain your answer to question d i in terms of the change in the oxidation state of this atom mark e using the information given in table deduce an equation for the redox reaction that would occur when hydroxide ions are added to hocl marks question continues on the next page turn over wmp jun chem do not write outside the box f table is repeated to help you answer this question table e v zno s h o i e zn s oh aq fe aq e fe s o g h o i e oh aq hocl aq h aq e cl g h o i the half equations from table that involve zinc and oxygen are simplified versions of those that occur in hearing aid cells a simplified diagram of a hearing aid cell is shown in figure figure air hole aqueous alkaline paste a stainless steel lid porous partition acting as salt bridge zinc powder in alkaline paste insulator b stainless steel can f i use data from table to calculate the e m f of this cell mark answer wmp jun chem do not write outside the box f ii use half equations from table to construct an overall equation for the cell reaction mark f iii identify which of a or b in figure is the positive electrode give a reason for your answer marks positive electrode reason f iv suggest one reason other than cost why this type of cell is not recharged mark turn over for the next question turn over wmp jun chem

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