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.

Explanation

The skeletal equation is `CI_(2)(aq)+SO_(2)+H_(2)(l)rarrCI^(-)(aq)+SO_(4)^(2-)(aq)`
Reduction half equation `CI_(2)(aq)rarrCI^(-)(aq)`
oxidation half equation `overset(+4)SO_(2)(aq)rarroverset(+6)SO_(4)^(2-)(aq)`
oxidation addding Eq (i) and Eq (ii) we have
`SO_(2)(aq)+2H_(2)O(l)rarrSO_(4)^(2-)(aq)+4H^(+)(aq)+2e^(=)`
adding Eq (i) and Eq (ii) we have
`CI_(2)(aq)+SO_(23)+2H_(2)O(l)rarr2CI^(-)(aq)+SO_(4)^(2-)(aq)+4H^(+)(aq)`
this represents the balance redox reaction