1) 3K2MnO4+2H2O=

=2KMnO4+MnO2+4KOH

Mn{6+} - e = Mn{7+}. |2

Mn{6+} + 2e = Mn{4+}. |1

2) 3HClO3=HClO4+2ClO2+H2O

Cl{5+} - 2e = Cl{7+}|1

Cl{5+} + e = Cl{4+} |2

3) 3HNO2=HNO3+2NO+H2O

N{3+} - 2e = N{5+}. |1

N{3+} + e = N{2+}. |2