Question

With respect to the electrolysis of copper (II) sulphate solution using copper electrodes, which statement is correct?

• A. Copper metal is deposited at the negative electrode.
• B. Oxygen gas is produced at the positive electrode.
• C. The positive electrode increases in mass.
• D. The negative electrode decreases in mass.

Hint:

In this process, the blue color of the CuSO_4 solution does not fade because the number of Cu^2+ ions leaving the solution at the cathode is replenished by the anode!

Answer 1

The Correct Option is A

Step 1: Understanding the Electrolysis Setup:
When using active copper electrodes, the anode (positive) dissolves and the cathode (negative) receives deposits.
Step 2: Reaction at the Cathode (Negative):
Copper ions (Cu^2+) from the solution move toward the cathode, gain electrons, and turn into solid copper: [ Cu^2+ + 2e^- Cu(s) ] This results in an increase in the mass of the negative electrode.
Step 3: Reaction at the Anode (Positive):
The copper anode itself loses electrons and dissolves into the electrolyte: [ Cu(s) Cu^2+ + 2e^- ] This results in a decrease in the mass of the positive electrode.
Step 4: Final Answer:
Statement (a) is the only correct observation for this specific electrolytic process.