What is the oxidation state of Mn in KMnO₄?

K = +1, O₄ = −8, so Mn = +7. KMnO₄ is a strong oxidising agent in both acidic and basic media.

What is a disproportionation reaction?

A reaction in which the same element is simultaneously oxidised and reduced. Example: Cl₂ + 2NaOH → NaCl + NaClO + H₂O (Cl goes from 0 to −1 and +1).

What is the oxidation state of oxygen in H₂O₂?

In H₂O₂ (hydrogen peroxide), oxygen has oxidation state −1, not the usual −2. H = +1, so O = −1 to balance to 0.

Oxidation and Reduction

Redox Reactions • Class 11 Chemistry • NCERT • CBSE

Oxidation: loss of electrons (OIL). Reduction: gain of electrons (RIG). Oxidising agent gets reduced. Reducing agent gets oxidised. Oxidation state of O = −2 (usually). Oxidation state of H = +1 (usually).

Key Formulas

Oxidation: loss of electrons
Reduction: gain of electrons
Sum of oxidation states = 0 (neutral molecule)
Sum of oxidation states = charge (polyatomic ion)

Frequently Asked Questions

What is the oxidation state of Mn in KMnO₄?: K = +1, O₄ = −8, so Mn = +7. KMnO₄ is a strong oxidising agent in both acidic and basic media.
What is a disproportionation reaction?: A reaction in which the same element is simultaneously oxidised and reduced. Example: Cl₂ + 2NaOH → NaCl + NaClO + H₂O (Cl goes from 0 to −1 and +1).
What is the oxidation state of oxygen in H₂O₂?: In H₂O₂ (hydrogen peroxide), oxygen has oxidation state −1, not the usual −2. H = +1, so O = −1 to balance to 0.

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