The number of electrons involved in the reduction of permanganate… — Solution | JEE Chemistry

NVAEasyJEE 2023Oxidation Number & Redox Reactions

The number of electrons involved in the reduction of permanganate to manganese dioxide in acidic medium is _____.

Answer

Correct answer:3

Standard Method

Given: Reduction of permanganate to manganese dioxide in acidic medium.

Find: The number of electrons involved.

In acidic medium, permanganate is reduced to manganese dioxide:

\mathrm{MnO_4^- + 4H^+ + 3e^- \rightarrow MnO_2 + 2H_2O}

Therefore, the number of electrons involved is $3$ .

Using the half-reaction for reduction of permanganate to $\mathrm{Mn^{2+}}$ instead of $\mathrm{MnO_2}$ is incorrect because the product given here is manganese dioxide. Always use the half-reaction matching the stated product.
Ignoring the medium is incorrect because the balancing changes in acidic, basic, and neutral media. Always check the medium before counting $e^-$ in the half-reaction.

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