Q. Electrolysis of an aqueous solution of copper sulphate using copper electrodes gives:
Answer: Copper at cathode and oxygen at anode.
Notes: Copper is deposited at the cathode and is dissolved at the anode. Consequently the concentration of copper ions in solution remains constant. This can be used as a method of purification of copper as only pure copper is deposited at the cathode. Bubbles of gas (oxygen) are formed and evolved at the anode.

• Cathode reaction: Cu2+ + (aq) + 2e– —> Cu(s); and
• Anode reaction: 2H2O(l ) —> O2(g) + 4H+(aq) + 4e-