A balanced chemical equation?

A balance chemical equation is an equation describing a chemical reaction with the right number of molecules to cancel out each side of the equation.

For example:

H2 + O2 - > H2O

Make sure the number of molecules in your reactants equal the number of molecules in your product

2H2 + O2 - > 2H2O

(4 hydrogens and 2 oxygens = 4 hydrogens and 2 oxygens)