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Question
During the electrolysis of copper (II) sulphate solution using platinum as cathode and carbon as anode:
- What do you observe at the cathode and at the anode?
- What change is noticed in the electrolyte?
- Write the reactions at the cathode and at the anode.
Solution
- Cathode: Reddish brown deposition of copper occurs at the cathode.
Anode: Colourless gas is evolved at the anode. - The colour of the electrolytes changes gradually from blue to colourless.
- At the cathode:
\[\ce{Cu^{2+} + 2e- -> Cu}\]
At the anode:
\[\ce{OH- -1e^- -> OH}\]
\[\ce{4OH -> 2H2O + O2 ^}\]
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