FeSO4 + KMnO4 + H2O

18FeSO4 + 6KMnO4 + 12H2O → 3K2SO4 + 6MnO2 + 8Fe(OH)3 + 5Fe2(SO4)3

Mn+7 + 3e → Mn+4

Fe2+ → Fe3+ + 1e

6aFeSO4 + 2aKMnO4 + 3bH2O → aK2SO4 + 2aMnO2 + 2bFe(OH)3 + cFe2(SO4)3

Fe: 6a = 2b + 2c

S: 6a = a + 3c

O: 24a + 8a + 3b = 4a + 4a + 6b + 12c

Tự cho a = 1, tính b = 8/3; c = 5/3

—> a = 3, b = 8, c = 5