Electrolysis products with reactive copper electrodes

Steps:

• Identify ions in aqueous CuSO₄: Cu²⁺, SO₄²⁻, plus H⁺ and OH⁻ from water.
• At cathode (reduction), Cu²⁺ + 2e⁻ → Cu deposits as metal, preferred over 2H⁺ + 2e⁻ → H₂ due to lower reduction potential.
• At anode (oxidation), copper electrode oxidizes: Cu → Cu²⁺ + 2e⁻, releasing aqueous Cu²⁺ ions instead of O₂ from water.
• Overall, Cu deposits at cathode; solution concentration stays constant as anode replenishes Cu²⁺.

Why A is correct:

• With copper electrodes, anode reaction is Cu(s) → Cu²⁺(aq) + 2e⁻, producing aqueous Cu²⁺ ions per standard electrode potential rules.

Why the others are wrong:

• B: Cathode produces H₂ gas only with inert electrodes, not copper.
• C: Anode produces O₂ gas with inert electrodes, not copper.
• D: Both O₂ at anode and H₂ at cathode occur with inert electrodes in CuSO₄.

Final answer: A