Redox reactions involve oxidation and reduction processes. Most involve ions and occur in solutions and are described by ionic equations. Like other chemical equations, they need to be mass and atom balanced because mass and atoms are not made or destroyed in reactions. When dealing with ionic equations, extra care must also be taken to ensure that the equations are charge balanced as charge can also not be made or destroyed.
A common tactic is to divide the whole process into individual equations for the oxidation and reduction processes separately. These are called "half equations" and are mass and atom balanced first.
- In the oxidation process, a substance loses one or more electrons: "Loss of Electrons is Oxidation" (OIL)
- In the reduction process, a substance gains one or more electrons: "Reduction Is Gain" (RIG)