Hydrogen peroxide solution (20 ml) reacts quantitatively with a solution of KMnO₄ (20 ml) acidified with dilute H₂SO₄. The same volume of the KMnO₄ solution is just decolourized by 10 ml of MnSO₄ in n

Question

Hydrogen peroxide solution (20 ml) reacts quantitatively with a solution of KMnO₄ (20 ml) acidified with dilute H₂SO₄. The same volume of the KMnO₄ solution is just decolourized by 10 ml of MnSO₄ in neutral medium simultaneously forming a dark brown precipitate of hydrated MnO₂. The brown precipitate is dissolved in 10 ml of 0.2 M sodium oxalate under boiling condition in the presence of dilute H₂SO₄. The strength of H₂O₂ solution in mg per 100 ml solution is

TestHub · Accepted Answer

Oxalate used = 10×0.2 = 2 mmol; MnO₂ + C₂O₄²⁻ is 1:1, so MnO₂ = 2 mmol. From 2MnO₄⁻ + 3Mn²⁺ → 5MnO₂, MnO₄⁻ = 2×2/5 = 0.8 mmol in 20 ml, i.e. KMnO₄ = 0.04 M. H₂O₂ reacting with 0.8 mmol MnO₄⁻ (2:5 ratio) = 2.0 mmol in 20 ml = 10 mmol per 100 ml = 10×34 = 340 mg/100 ml. Ans 0340.

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