Question

Balance the following redox equation using the smallest integers possible and select the correct coefficient for the hydrogen sulfite ion. MnO41-(aq) + HSO31-( aq) + H+( aq) → Mn2 ( aq) + SO42–( aq) + H2O( l)

Answer 1

Answer:

Coefficient of $HSO_{3}^{-}$ is 5

Explanation:

Oxidation: $MnO_{4}^{-}(aq)\rightarrow Mn^{2+}(aq)$

• Balance O and H in acidic medium: $MnO_{4}^{-}(aq)+8H^{+}(aq)\rightarrow Mn^{2+}(aq)+4H_{2}O(l)$
• Balance charge : $MnO_{4}^{-}(aq)+8H^{+}(aq)+5e^{-}\rightarrow Mn^{2+}(aq)+4H_{2}O(l)$ .............(1)

Reduction: $HSO_{3}^{-}\rightarrow SO_{4}^{2-}$

• Balance O and H in acidic medium : $HSO_{3}^{-}(aq)+H_{2}O(l)\rightarrow SO_{4}^{2-}(aq)+3H^{+}(aq)$
• Balance charge : $HSO_{3}^{-}(aq)+H_{2}O(l)-2e^{-}\rightarrow SO_{4}^{2-}(aq)+3H^{+}(aq)$ ..............(2)

$[2\times eq(1)]+[5\times eq(2)]$ -

Balanced equation: $2MnO_{4}^{-}(aq)+5HSO_{3}^{-}(aq)+H^{+}(aq)\rightarrow 2Mn^{2+}(aq)+5SO_{4}^{2-}(aq)+3H_{2}O(l)$

Coefficient of $HSO_{3}^{-}$ is 5