Question

how to chemical equations balance

Answer 1

Once we do that, the number of nitrogen (N) atoms on both sides is balanced. However, the number of hydrogen (H) atoms is not balanced on both sides. We need to make use of another coefficient in front of H2. This time, we put a coefficient of 3 in front of H2 tobalance the chemical equation.

Answer 2

equate the number of atoms of each element on both sides of reaction.
$H_{2} +O_{2} = 2H_{2} O$
here H and O on both sides is balanced