Write the skeletons of the oxidation and reduction half-reactions.
(The skeleton reactions contain the formulas of the compounds oxidized and
reduced, but the atoms and electrons have not yet been balanced.) See Example.
Balance all elements other than H and O.
Balance the oxygen atoms by adding H2O molecules where
Balance the hydrogen atoms by adding H+ ions where needed.
Balance the charge by adding electrons, e-.
If the number of electrons lost in the oxidation half-reaction is not
equal to the number of electrons gained in the reduction half-reaction, multiply
one or both of the half- reactions by a number that will make the number of
electrons gained equal to the number of electrons lost.
7: Add the 2 half-reactions as if they were mathematical equations.
The electrons will always cancel. If the same formulas are found on opposite
sides of the half-reactions, you can cancel them. If the same formulas are found
on the same side of both half-reactions, combine them.
8: Check to make sure that the atoms and the charges balance.