# How can I balance the redox reaction of sulfur dioxide with oxygen?

How do I balance this reaction using half-redox equations? $$\ce{2SO2 + O2->2SO3}$$

My work is:

Oxidation: $\ce{SO2 + H2O -> SO3 + 2e- + 2H+}$

Reduction: $\ce{H2O + 2e- + O2 -> SO3 + 2H+}$

Total: $\ce{SO2 + 2H2O + O2 -> 2SO3 + 4H+}$

BUT it's false. What did I do wrong?

• Your reduction formula is wrong. For one thing you have no sulfur containing species on the reactant side and the reactant side has a charge of -2 while the product side shows a charge of +2, this is a violation of charge neutrality, both sides must have the same overall charge. Nov 10, 2014 at 15:32