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^- water, a proton, and or an hydroxide group 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 oxygen and hydrogen
3. Balance oxygen by adding H₂O water
4. Balance hydrogen by adding H⁺ a proton
5. Balance the charges by adding e^- an electron
6. Balance e^- an electron 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 oxygen and hydrogen
3. Balance oxygen by adding H₂O a molecule of water
4. Balance hydrogen by adding H⁺ a proton
5. Balance the charges by adding e^- an electron
6. Neutralize H⁺ by adding OH^- a proton by adding an hydroxide group
7. Balance H⁺, OH^-, and e^- a proton, an hydroxide group and an electron and add up the half-reactions