Given the balanced equation representing the reaction between methane and oxygen: according to this equation, what is the mole ratio of oxygen to methane?.

The reaction considered here is

a CH₄ + b O₂   ⇒   c CO₂ + d H₂O

where a, b, c, d are unknown coefficients.

To balance the reaction, we want the same number of the same atoms on either side, so

• C : a = c

• H : 4a = 2d

• O : 2b = 2c + d

Suppose a = 1; then c = 1 and d = 2 and b = 2. So the balanced reaction is

CH₄ + 2 O₂   ⇒   CO₂ + 2 H₂O

and this means the mole ratio of oxygen to methane is 2 to 1.