1. CuO+H2=Cu+H2O

Cu{2+} + 2e- =Cu{0} | 1

H2{0} - 2e- =2H{+} | 1

2. 3H2+N2=2NH3

H2{0} - 2e- = 2H{+} | 3

N2{0} + 3e- = 2N{3} | 2

3. 4Al+3O2=2Al2O3

Al{0} - 3e- = Al{3+}. | 4

O2{0} + 4e- = 2O{2-} | 3

4. 2KMnO4=K2MnO4+MnO2+O2

Mn{7+} + e- = Mn{6+}. |1

Mn{7+} + 3e- = Mn{4+} |1

2O{2-} - 4e- = O2{0}. |1

5. 2NaNO3=2NaNO2+O2

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

2O{2-} - 4e- = O2{0} |1

6. 4NH3+5O2=4NO+6H2O

N{3-} - 5e- = N{2+}. |4

O2{0} + 4e- = 2O{2-} |5

7. 4NH3+3O2=2N2+6H2O

2N{3-} - 6e- = N2{0} |2

O2 + 4e- = 2O{2-}. |3

8. 8Na++10HNO3=8NaNO3+NH4NO3+3H2O

(тут ошибка в уравнении - не О2, а Н2О в продуктах)

Na{0} - e- = Na{+}. |8

N{5+} + 8e- = N{3-} |1