OCR A Jun 2013 Paper 5 Q7

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7 Standard electrode potentials for seven redox systems are shown in Table 7.1. You may need to use this information in parts (a)(d) of this question. 16 Redox system 1 2 3 4 5 6 7 Mg2+(aq) + 2e Cu2+(aq) + 2e Al3+(aq) + 3e Fe3+(aq) + e I2(aq) + 2e Cl2(g) + 2e ClO(aq) + 2H+(aq) + e Mg(s) Cu(s) Al(s) Fe2+(aq) 2I(aq) 2Cl (aq) Cl2(g) + H2O(l) E o / V 2.37 +0.34 1.66 +0.77 +0.54 +1.36 +1.63 (a) Define the term standard electrode potential. Include all standard conditions in your answer. Table 7.1[2] (b) An electrochemical cell can be made based on redox systems 1 and 2. Write down the standard cell potential of this cell. standard cell potential =V [1] (c) Using redox systems 3, 4 and 5 only in Table 7.1, predict three reactions that might be feasible. (i) Write the overall equation for each predicted reaction.[3]OCR 2013<br />
 (ii) Give two reasons why it is uncertain whether reactions predicted from E o values may actually take place. 17[2] (d) In aqueous acid, Cl (aq) ions react with ClO(aq) ions to form chlorine gas, Cl2(g). In aqueous alkali, chlorine gas, Cl2(g), reacts to form Cl (aq) and ClO(aq) ions. Explain this difference. Use Table 7.1 to help you with your answer.[4] In acidic conditions, Sn2+ ions react with IO3 (i) What is the oxidising agent in this reaction?ions to produce iodine and Sn4+ ions. Explain your answer. (e)[1] (ii) Construct an equation for this reaction.[2]OCR 2013 [Total: 15] Turn over<br />

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