Question

During the electrolysis of copper (II) sulphate solution using platinum as cathode and carbon as anode:

1. What do you observe at the cathode and at the anode?
2. What change is noticed in the electrolyte?
3. Write the reactions at the cathode and at the anode.

Answer 1

1. Cathode: Reddish brown deposition of copper occurs at the cathode.
   Anode: Colourless gas is evolved at the anode.
2. The colour of the electrolytes changes gradually from blue to colourless.
3. At the cathode:
   \[\ce{Cu^{2+} + 2e- -> Cu}\]
   At the anode:
   \[\ce{OH- -1e^- -> OH}\]
   \[\ce{4OH -> 2H2O + O2 ^}\]