Q46Short answer
A solution of KMnO4 on reduction yields either a colourless solution or a brown precipitate or a green solution depending on pH of the solution. What different stages of the reduction do these represent and how are they carried out?
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Oxidising behaviour of KMnO4 depends on pH of the solution. In acidic medium (pH < 7) MnO4– + 8H+ + 5e– → Mn2+ + 4H2O (Colourless) In alkaline medium (pH>7) MnO4– + e– → MnO42– (Green) In neutral medium(pH=7) – – MnO4 + 2H2O + 3e– → MnO2 + 4OH (Brown precipitate)