Redox reactions are oxidation-reduction chemical reactions in which the reactants undergo a change in their oxidation states. . It can be noted that any redox reaction can be broken down into two half-reactions, namely the oxidation half-reaction and the reduction half-reaction. While writing the half-reactions separately, each of them must be balanced in a way that all the electrons are accounted for.
The above-given equation is an example of the half-reaction. During the reaction, two electrons are transferred and the oxidation number of iodine (I) changes from -1 to 0.
2I–(aq) → I2 (s) + 2e