Complete Theory

Worked Examples

Example 1Assigning oxidation numbers in

\mathrm{K_2Cr_2O_7}

Example 2Balancing

\mathrm{MnO_4^- + Fe^{2+}}

in acidic medium

Exercise 1Oxidation numbersMedium

📋 Problem to solve

Assign the oxidation number of each atom in

\mathrm{H_3PO_4}

(phosphoric acid) and

\mathrm{H_2SO_4}

(sulfuric acid).

📌 Given data

H₃PO₄: H +1, O −2H₂SO₄: H +1, O −2

Exercise 2Redox balancingMedium

📋 Problem to solve

Balance the redox reaction

\mathrm{Cr_2O_7^{2-} + SO_3^{2-} \to Cr^{3+} + SO_4^{2-}}

in acidic medium.

📌 Given data

Cr₂O₇²⁻ (Cr +6 → +3)SO₃²⁻ (S +4 → +6)

Exercise 3Redox in basic mediumHard

📋 Problem to solve

Balance in basic medium:

\mathrm{Cl_2 \to Cl^- + ClO^-}

(chlorine disproportionation).

📌 Given data

Cl₂ (Cl 0) → Cl⁻ (−1) + ClO⁻ (Cl +1)

📚

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