When `SO_(2)` is passed through an aqueous solution of Fe (III), i.e., ferric salt, it is reduced to Fe (II) i.e., ferrous salt. Here, `SO_(2)` acts as a reducing agent.
`underset(("Oxide agent"))underset("Ferric ion")(2"Fe"^(3+))+underset("agent")underset("Reducing")(SO_(2))+2H_(2)O tounderset("ion")underset("Ferrous")(2"Fe"^(2+))+SO_(4)^(2-)+4H^(+)`
