F.4 Chem electrolysis

1.
Lead(II) ion would be preferentiallydischarged at the cathode.

lead(II) ion and hydrogen ions migrate to the cathode. Because lead(II) ion ismore concentrated than hydrogen ion, lead(II) ion is preferentially dischargedand thus lead metal is deposited at the cathode.


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2.
Copper(II) ion would be preferentiallydischarged at the cathode.

Copper(II) ion and hydrogen ions migrate to the cathode. Because copper(II) ionis reduced more readily than hydrogen ion, copper(II) ion is preferentiallydischarged and thus copper metal is deposited at the cathode.

2014-06-08 21:05:59 補充：
The questions are about the basic concepts of electrolysis. I think you have to study the chapter of electrolysis from your text book first.

For case 2, I think both the concentration of Copper (II) ions and hydrogen ions are small. Thus, the concentration should not be the main consideration. The ECS would rather be the major consideration for preferential discharge.