Balancing Redox Balancing Redox ReactionsReactions

StepsSteps::

1. Assign oxidation numbers

2. Write half reactions

3. Balance electrons to determine coefficients needed

2HgO O2 + 2Hg+2 -2 0 0

Hg+2 + 2e- Hg0 Reduction

Problem 1:

O-2 O0 + 2e- Oxidation

2KClO3 2KCl + 3O2

+1 +5 -2 +1 -1 0

6e- + Cl+5 Cl-1 Reduction

Problem 2:

3(O-2 O0 + 2e-) Oxidation

2HCl + Zn ZnCl2 + H2

+1 -1 0 +2 -1 0

2e- + 2H+1 H20 Reduction

Problem 3:

Zn0 Zn+2 + 2e- Oxidation

2Ag NO3 + Cu Cu(NO3)2 + 2Ag+1 +5 -2 0 +2 +5 -2 0

2e- + 2Ag+1 2Ag0 Reduction

Problem 4:

Cu0 Cu+2 + 2e- Oxidation

4NH3 + 3O2 2N2 + 6H2O -3 +1 0 0 +1 -2

12e- + 3O20 6O-2 Reduction

Problem 5:

4N-3 2N20 + 12e- Oxidation

3Mg + 2Al(NO3)3 2Al + 3Mg(NO3)2

0 +3 +5 -2 0 +2 +5 -2

6e- + 2Al+3 2Al0 Reduction

Problem 6:

3Mg0 3Mg+2 + 6e- Oxidation

3Ca + 2Al3+ 3Ca2+ + 2Al 0 +3 +2 0

6e- + 2Al+3 2Al0 Reduction

Problem 6:

3Ca0 3Ca+2 + 6e- Oxidation

2Fe3+ + Sn2+ 2Fe2+ + Sn4+

2e- + 2Fe+3 2Fe+2 Reduction

Problem 7:

Sn+2 Sn+4 + 2e- Oxidation

2HNO3 + 3MnCl2 + 6HCl 2NO + 3MnCl4 + 4H20+1 +5 -2 +2 -1 +1 -1 +2 -2 +4 -1 +1 -2

6e- + 2N+5 2N+2 Reduction

Problem 8:

3Mn+2 3Mn+4 + 6e- Oxidation

K2(Cr2O7) + 14HCl 3Cl2 + 7H2O + 2CrCl3 + 2KCl+1 +6 -2 +1 -1 0 +1 -2 +3 -1 +1 -1

6e- + Cr2+6 2Cr+3 Reduction

Problem 9:

6Cl-1 3Cl20 + 6e- Oxidation