1) (MnO4)- +e- = (MnO4)2- | 1 | 2 | 2 |
(SnO2)2- -2e- + 2OH- = (SnO3)2- + H2O | 2 | | 1 |;
2(MnO4)- + (SnO2)2- + 2OH- = 2(MnO4)2- + (SnO3)2- + H2O;
2KMnO4 + Na2SnO2 + 2NaOH = Na2SnO3 + K2MnO4 + Na2MnO4 + H2O;
2) (MnO4)- +3e- + 2H2O = MnO2 + 4OH- | 3 | 6 | 2 |
Fe -2e- + 2OH- = Fe(OH)2 | 2 | | 3 |;
2(MnO4)- + 3Fe + 4H2O = 2MnO2 + 3Fe(OH)2 + 2OH-;
2NaMnO4 + 3Fe + 4H2O = 2MnO2 + 3Fe(OH)2 + 2NaOH.