Question

Complete the following ionic equations:

$5\text{SO}_3^{2-} + 2\text{MnO}_4^{-} + 6\text{H}^+ \longrightarrow$

Hint:

Remember to balance charges and atoms carefully when working with ionic equations in redox reactions.

Answer 1

For equation (I), the oxidation states of manganese change from +6 to +7 in the permanganate ion, indicating an oxidation. In acidic medium, sulfur dioxide ($\text{SO}_2$) is oxidized to sulfate ($\text{SO}_4^{2-}$). The balanced ionic equation for this reaction is:
$5\text{SO}_3^{2-} + 2\text{MnO}_4^{-} + 6\text{H}^+ \longrightarrow 2\text{MnO}_4^{2-} + 3\text{SO}_4^{2-} + 3\text{H}_2\text{O}$.
For equation (II), the iodide ion is oxidized to iodine by permanganate in an acidic medium. The balanced ionic equation is:
$2\text{MnO}_4^{-} + \text{H}_2\text{O} + \text{I}^- \longrightarrow 2\text{MnO}_2 + \text{I}_2 + 2\text{OH}^-$.