CIE Mar 2017 v2 Paper 4 Q3

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(a) The diagram shows the apparatus used to measure the standard electrode potential, E o, of Fe3+(aq) / Fe2+(aq). PMT (i) Identify what the letters A to F represent. ADBECF[3] (ii) Label the diagram to showwhich is the positive electrode, the direction of electron flow in the external circuit. Use the Data Booklet to help you. [1] (b) In another experiment, an Fe3+(aq) / Fe2+(aq) half-cell was connected to a Cu2+(aq) / Cu(s) half-cell. Determine the standard cell potential, and the circuit is completed. Use the Data Booklet to help you. , when these two half-cells are connected by a wire =V [1]UCLES 2017 9701/42/F/M/17<br /> PMT (c) (i) The E o of Ni2+(aq) / Ni(s) is 0.25 V. State and explain how the electrode potential changes if the concentration of Ni2+(aq) is decreased.[1] (ii) The E o of Cr3+(aq) / Cr2+(aq) is 0.41 V. Calculate the electrode potential when [Cr3+(aq)] is 0.60 mol dm3 and [Cr2+(aq)] is 0.15 mol dm3. Use the Nernst equation. E = E o + 0.059 log [oxidised species] [reduced species] E =V [2] [Total: 8]UCLES 2017 9701/42/F/M/17 [Turn over<br />

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