Chemistry Form 4: Chapter 6 - Purification of Metal

• The anode is a impure copper.
• The cathode is a pure copper.
• When electricity is passed through the cell, the copper is dissolved at anode where Cu²⁺ ions go into solution. Anode copper becomes thinner.

• At cathode, copper ions are selectively discharge and deposited. Cathode copper becomes thicker.

The blue intensity of solution remains unchanged because concentration of copper (II) ions in the solution remains unchanged. The rate at which copper enter into electrolyte from anode is equal to the rate at which the copper ions discharged at cathode.