What are the coefficients needed to balance the equation for the combustion of methane?
CH4 + O2 + CO2 + H2O

CH
4
+ O
2
→
CO
2
+ H
2
O
First look at the C atoms. At first glance they are balanced with 1 C on each side.
Now look at the H atoms. They are not balanced. There are 4 H atoms on the left side and 2 H atoms on the right. Place a coefficient of 2 in front of the
H
2
O
. We now have 4 H atoms on both sides.
CH
4
+ O
2
→
CO
2
+ 2H
2
O
Now look at the O atoms. They are not balanced. There are 2 O atoms on the left side and 4 on the right. Place a coefficient of 2 in front of the
O
2
. We now have 4 O atoms on both sides.
CH
4
+ 2O
2
→
CO
2
+ 2H
2
O
The equation is now balanced. Each side has 1 C atom, 4 H atoms, and 4 O atoms.