2Mn
2+ + 5S2O8
2– + 8H2O ® 2MnO4
– + 10SO4
2– + 16H
+
Potassium permanganate forms dark purple (almost black) crystals which
are isostructural with those of KClO4 The salt is not very soluble in water
(6 4 g/100 g of water at 293 K), but when heated it decomposes at 513 K 2KMnO4 ® K2MnO4 + MnO2 + O2
It has two physical properties of considerable interest: its intense colour
and its diamagnetism along with temperature-dependent weak
paramagnetism