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a salt of permanganic acid (HMnO4). Permanganate crystals are nearly black, with a greenish violet hue, while permanganate solutions are usually tinted the red-violet color of the ion. Permanganates of sodium and bivalent metals dissolve freely in water, but KMnO4 is only sparingly soluble. Permanganates are extremely unstable upon heating. For example, KMnO4 decomposes at temperatures as low as 200°C according to the equation 2KMnO4 = K2MnO4 + MnO2+ O2.
Permanganates are strong oxidizing agents, especially in an acid medium; thus, for example, Mn(VII) reduces to Mn(II), as in MnSO4. Their use as oxidizing agents in chemistry is widespread, and in medicine permanganates are used as disinfectants and in the treatment of burns.