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Question
How will you obtain pure potassium permanganate (KMnO4) crystals from its ore, pyrolusite? Give the steps involved and the reactions.
Solution
Potassium permanganate crystals (KMnO4) from pyrolusite:
It involves two steps
Step-1: Conversion of pyrolusite into potassium manganate
\[\ce{2MnO2 + 4KOH + O2 ->[Fuse]2K2MnO4 + 2H2O}\]
Step-2: Conversion of potassium manganate into potassium permanganate (By isolation)
\[\ce{\underset{\text{(Aqueous solution)}}{K2MnO4 + Cl2} -> 2KMnO4 + 2KCl}\]
On crystallisation, the crystals of KMnO4 appear, which are separated and dried.
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