Question

Why is `KMnO_4` an oxidizing agent?

Answer 1

Because manganese metal is in its highest oxidation state (`Mn(VII+)`, and it is likely to be reduced in any reaction.

Explanation:

And if it is likely to be reduced, it is an electron sink, and therefore an `"oxidizing agent"`. Typically, permanganate is reduced to colourless `Mn^(2+)`:

`MnO_4^(-) + 8H^(+) + 5e^(-)rarr Mn^(2+) + 4H_2O`

Mass and charge are balanced here, so at least the reaction is viable. The macroscopic change is usually from deeply purple permanganate to almost colourless `Mn^(2+)` ion, so this reaction is convenient in that it is self-indicating.