(1) Identify the half reactions and work with each separately. Note: some species may occur in both

(2) For each half reaction:

a) balance the atoms being oxidized or reduced

b) balance other atoms besides O or H

c) balance O atoms by adding H₂O to one side

d) balance H atoms:

acidic solution

add H⁺ to one side


basic solution

(i) change all H⁺ to H₂O

(ii) add same number of OH^- to other side

(iii) cancel any H₂O appearing on both sides

e) balance each reaction in electrical charge by adding electrons

(3) Combine the half reactions:

a) multiply each half reaction by a factor chosen to cancel out the electrons when added together

b) cancel species appearing on both sides

Example