Preparation of `KMnO_(4)` Potassium permanganate is prepared by the fusion of `MnO_(2)` with an alkali metal hydroxide and an oxidising agent like `KNO_(3)` It forms dark green, `K_(2)MnO_(4)` which disproportionates in a neutral or acidic solution to give permanganate.
i) `2MnO_(2)+4KOH+O_(2) overset(KNO_(2))rarr2K_(2)MnO_(4)+2H_(2)O`
ii) `3MnO_(4)^(2-)+4H^(+) rarr 2MnO_(4)^(-)+MnO_(2)+2H_(2)O`
or `3K_(2)MnO_(4)+2H_(2)SO_(4) rarr underset("Potassium permanganate")(2KMnO_(4)+2K_(2)SO_(4)+MnO_(2)+2H_(2)O)`
