This is an oxidation-reduction (redox) reaction:

C-IV - 8 e- → CIV (oxidation)

4 O0 + 8 e- → 4 O-II (reduction)

CH4 is a reducing agent, O2 is an oxidizing agent.

### Word equation

methane + oxygen → carbon dioxide + water

### Input interpretation

CH4 + O2 → CO2 + H2O

Methane oxygen carbon dioxide water

### Balanced equation

Balance the chemical equation algebraically:

CH4 + O2 → CO2 + H2O

Add stoichiometric coefficients, c;, to the reactants and products:

c1CH4 + c2O2 → c3CO2 + c4H2O

Set the number of atoms in the reactants equal to the number of atoms in the products for C, H and O:

C: c1 = c3

H: 4c1 = 2c4

O: 2c2 = 2c3 + c4

Since the coefficients are relative quantities and underdetermined, choose a coefficient to set arbitrarily. To keep the coefficients small, the arbitrary value is ordinarily one. For instance, set c1 = 1 and solve the system of equations for the remaining coefficients:

c1=1 c2=2

c3 = 1 c4=2

Substitute the coefficients into the chemical reaction to obtain the balanced equation: