Half-Reaction Method for Balancing Redox Reactions
1)
Divide the skeleton equation into oxidation and reduction half-rxns.
2)
Balance the atoms in each half-rxn. Balance the total charge of each half-rxn by
adding e- s to the product side of the oxidation step and adding e- s to the
reactant side of the reduction step.
3)
Multiply one (or both) half-rxns by an integer so that the number of e- s lost in
one half-rxn equals the number of e- s gained in the other half-rxn.
4)
Add the half-rxns and include phase labels.
Additional Rules for Reactions in Acidic or Basic Solution (add to step 2)
A)
If the rxn occurs in acidic solution, H2O can be added to balance oxygen atoms
and H+ ions can be added to balance hydrogens.
B)
If the rxn occurs in basic solution, use the same method as described in A), and
in step 4, add one OH- ion to both sides of the balanced rxn for every H+ present.