(b) (i)The e.m.f. of the cell was measured as 0.62 volts. Taking the standard electrode potential of Cu/Cu2+ as = +0.34 volts, calculate the standard potential of the Co/Co2+ system. Be careful to indicate whether your answer is positive or negative.

Question

(ii) State the direction in which the electrons flow. [3]
(c) (i) What would you see if pieces of copper metal were added to an aqueous solution of cobalt
chloride?
(ii) What would you see if pieces of cobalt metal were added to an aqueous solution of copper (II)
chloride?

Answer 1

Co ==> Co^2+ + 2e Eo = ?
Cu^2+ + 2e ==> Cu Eo = 0.34
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Co + Cu^2+ ==> Cu + Co^2+ E = 0.62
So Eo Co + Eo Cu^2+ = Ecell = 0.62
Therefore, Co ==> Co^2+ must be +0.28 v because 0.28 + 0.34 = 0.62

The half cell releasing electrons is the anode and that is negative.
The other half cell is the cathode and is positive. Electrons flow from the negative to the positive.
If you add Co metal you will see Cu plating out on it. If you add Cu metal nothing happens.