Chemistry - Redox Reactions Question with Solution | TestHub

Oxidation half reaction: ${\mathrm{SO}}_2(\mathrm{g})+2{\mathrm{H}}_2\mathrm{O}(l)⟶{\mathrm{HSO}}_4^{-}(aq)+3{\mathrm{H}}^{+}(aq)+2e^{-}...(i)$ Reduction half reaction: ${\mathrm{MnO}}_4^{-}(aq)+8{\mathrm{H}}^{+}+5e^{-}⟶{\mathrm{Mn}}^{2+}(aq)+4{\mathrm{H}}_2\mathrm{O}(l)...(ii)$ Multiply eq. (i) by 5 and (ii) by 2 and then add $\begin{array}{rl}2{\mathrm{MnO}}_4^{-}(aq)+5{\mathrm{SO}}_2(g)& +2{\mathrm{H}}_2\mathrm{O}(l)+{\mathrm{H}}^{+}(aq)\\ & ⟶2{\mathrm{Mn}}^{+}(aq)+5{\mathrm{HSO}}_4^{-}(aq)\end{array}$ Thus, the stoichiometric coefficient of ${\mathrm{SO}}_2$ in the above balance equation is 5 .