This document describes the electrolysis of a copper(II) sulfate solution using copper electrodes. During electrolysis, copper ions and hydrogen ions move to the cathode where copper ions are discharged to form a brown copper deposit, while hydroxide and sulfate ions move to the anode where the copper electrode dissolves to release copper ions and electrons. The process results in the cathode gaining mass and thickness while the anode loses mass and becomes thinner, but the concentration and blue color of the copper ions in the solution remains unchanged.
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Type of electrodes
1. Type of electrodes used in the electrolysis.
Copper electrodes
Copper (II) sulphate
solution
Figure 4 Electrolysis of copper (II) sulphate solution using copper electrodes
From copper (II) sulphate Cu2+ , SO42-
From water H+ , OH-
CATHODE : Cu2+ ions and H+ ions move ANODE: OH- ions and SO42- ions move to
to the cathode. Cu2+ ion which is at a the anode. Copper electrode dissolves
lower position than H+ ion in the ES is /ionizes and releases electrons to form Cu2+
selected to be discharged. ions.
Cu2+ (aq) + 2e --ïƒ Cu (s) Cu ---ïƒ Cu2+ + 2e
Brown deposit is formed. The mass of The mass of the anode decreases and the
the cathode increases and the cathode anode becomes thinner.
becomes thicker.
The colour intensity of blue solution dose not change because the concentration of Cu2+ ions
in the solution remains unchanged. This is because the rate of formation of copper (II) ions,
at the anode is the same as the rate of discharge of copper (II) ions, at the cathode.
