F
used with KOH, oxidised
with air or KNO
2
3
2
4
MnO
MnO
;
manganate ion
−
→
42
4
Electrolytic oxidation in
alkaline solution
MnO
MnO
manganate
permanganate ion



Rationalised 2023-24
107
The d- and f- Block Elements
In the laboratory, a manganese (II) ion salt is oxidised by
peroxodisulphate to permanganate 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