Question

Why ${\mathrm{SO}}_2$ can act as oxidizing as well as reducing agent but ${\mathrm{H}}_2\mathrm{S}$ act as only a reducing agent?

Answer 1

Oxidizing agent:

• An oxidising agent (also known as an oxidizer or an oxidant) is a chemical species that tends to oxidize other substances, causing them to lose electrons and hence raise their oxidation state.

Reducing agent:

• A reducing agent is a chemical that loses electrons to other compounds in a redox process and is oxidized to a lower valency state.
• A reducing agent is one of the reactants in an oxidation-reduction reaction that reduces the other reactant by releasing electrons.

${\mathrm{SO}}_2$as oxidizing as well as reducing agent:

• In ${\mathrm{SO}}_2$, $\mathrm{S}$ is in an oxidation state that is $+4$ and its highest oxidation state is $+6$.
• Hence, can act both as reducing agent and oxidising agent.

${\mathrm{H}}_2\mathrm{S}$ act as only a reducing agent:

• In ${\mathrm{H}}_2\mathrm{S}$, $\mathrm{S}$ is in its lowest oxidation state that is $-2$.
• Hence, it can only act as a reducing agent only.