Step
5:
Finally, confirm that mass and charge are balanced. There is a +4 net charge on each side of
the reaction equation, and the atoms are stoichiometrically balanced.
As you may have noticed, balancing redox equations can be trickier and more involved than other
types of reactions because often one needs to supply additional chemical species like water and
protons to the equation, rather than simply playing with stoichiometric coefficients. The above
scheme is the most general one that can be applied; it may be that many intermediate steps can be
omitted if the equation is simpler. For example, for the equation:
Zn (s) + HCl (aq) → ZnCl 2 (aq) + H 2 (g)
one may balance it by just supplying coefficients.