Question

An electrolytic cell is set up using two platinum electrodes and an aqueous solution of copper (II) sulphate given below:

Name the ion discharged at the anode.

• A. Cu²⁺
• B. H⁺
• C. SO₄^2-
• D. OH^-

Answer 1

The correct option is D

OH^-

The ions present in the aqueous copper sulphate are $C{u}^{2+},H^{+},S{O}_4{}^{2-}$ and $O{H}^{-}$. The $S{O}_4{}^{2-}$ and OH${}^{-}$ ions both migrate to the anode. The $O{H}^{-}$ ions, being lower in the electrochemical series as compared to $S{O}_4{}^{2-}$ ions, discharge to form neutral OH radical. The neutral OH radical reunite to form water and oxygen.

$4O{H}^{-}-4e\to 4OH$

$2OH+2OH\to 2H_{2}O+O_2$

So, the product formed at the anode is $O_2$.