Chlorine is used to purify drinking water. Excess of chlorine is harmful. The excess of chlorine is removed by treating with sulphur dioxide. Present a balanced equation for this redox change taking place in water.

Solution:

The redox response is as given beneath:

Cl2(s)+SO2(aq)+H2O(l)→Cl(aq)–+SO4(aq)2–

The oxidation half response:

SO2(aq)→SO4(aq)2–

Add 2 electrons to adjust the oxidation no. :

SO2(aq)→SO4(aq)2–+2e–

Add ions to surplus the charge:

SO2(aq)→SO4(aq)2–+4H(aq)++2e–

Add to surplus 0 particles and ions:

The decrease half response:

Equilibrium Cl iotas:

Add 2 electrons to adjust the oxidation no. :

Add condition (1) and (2) to get the reasonable compound condition: