Balancing redox reactions

The electrons that are lost by the reducing agent are the same as the electrons gained by the oxidizing agent in a redox reaction. This means that in a redox reaction in addition to balancing the number of atoms for each element, the number of electrons also needs to be balanced.

In order to balance a redox reaction in an aqueous environment, it is important to first determine whether the environment is acidic or alkaline. Depending on the environment, H₂O, H⁺ and/or OH^- should be added to the reaction.

In an acidic environment, the steps to balance the reaction are:

1. Find the half-reactions
2. Balance all atoms except O and H
3. Balance oxygen by adding H₂O
4. Balance hydrogen by adding H⁺
5. Balance the charges by adding e^-
6. Balance e^- and add up the half-reactions

In an alkaline environment, the steps to balance the reaction are:

1. Find the half-reactions
2. Balance all atoms except O and H
3. Balance oxygen by adding H₂O
4. Balance hydrogen by adding H⁺
5. Balance the charges by adding e^-
6. Neutralize H⁺ by adding OH^-
7. Balance H⁺, OH^-, and e^- and add up the half-reactions