How is `KMnO_(4)` [Potassium permanganate] is prepared from `MnO_(2)`? Write equations.

Explanation

1) By the fusion of `MnO_(2)` with a Alkali like `KOH` in the presence of oxidising agent like `KNO_(3)`, potassium manganate is formed.
`2MnO_(2)+4KOH+O_(2)rarr 2K_(2)MnO_(4)+2H_(2)O`
2) The manganate in undergo disproportionation in acid medium to form permangnate ion.
`3MnO_(4)^(2-)+4H^(+)rarr 2MnO_(4)^(-)+MnO_(2)+2H_(2)O`