Question

In the reaction `2H_2S+SO_2 -> 3S+2H_2O`, what has been oxidized and what is the oxidizing agent?

Answer 1

Sulfide has been oxidized, and sulfur dioxide is the oxidizing agent.

Explanation:

This is an example of a comproportionation reaction in which sulfur compounds, in different oxidation states with respect to the sulfur, undergoes electron transfer to give a elemental sulfur (which is zerovalent).

`2H_2S rarr S +2H^(+) + 2e^-` `(i)`

(oxidation from `S(-II)` to `S(0)`)

`SO_2 + 4H^(+) + 4e^(-) rarr S + 2H_2O` `(ii)`

(reduction from `S(+IV)` to `S(0)`)

So `2xx(i) +(ii)` `=` `2H_2S +SO_2 rarr 3S +2H_2O`