# How can I balance this equation? ____ H2 + ____ O2 ---> ____ H2O

May 31, 2014

${H}_{2} + \frac{1}{2} {O}_{2} \to {H}_{2} O$

Cut the equation in half:

Reactants
H - 2
O - 2

Products
H - 2
O - 1

${O}_{2}$ is one oxygen molecule - there is only one oxygen atom in ${H}_{2} O$. So, in order to balance it, put a $\frac{1}{2}$ next ox ${O}_{2}$ - half of ${O}_{2}$ is ${O}_{1}$ ($O$) i.e. - one oxygen atom.