Question

Explain why the blue colour of copper chloride fades away gradually during electrolysis?

Answer 1

During electrolysis the ions present in the electrolyte are H⁺ and OH^- from water and Cu²⁺ and Cl^- from copper(II) chloride.

At the Cathode: 4OH^- + 4e^- $\to$ O₂ + 2H₂O
Oxygen from OH- ions is formed. Bubbles of colorless gas are formed.

At the anode: Cu²⁺ + 2e^- $\to$ Cu
Cu²⁺ are discharged because copper is less reactive than hydrogen. A red brown metal is formed.

The left over ions are H⁺ and Cl^- ions which bond together forming hydrochloric acid.

Copper Chloride solution is blue in color. But during this process, the blue color gradually fades away because copper chloride is being broken down. The solution becomes acidic becomes acidic because hydrochloric acid is formed.