The combustion of 1 mole of methane (CH4) in a domestic furnace requires 2 moles of O2 molecules, assuming the combustion was complete or ideal. To solve this problem, use stoichiometry of the reaction's balanced chemical equation:
CH4 + 2O2 --> CO2 + 2H2O
The ratio of CH4 to O2 in terms of moles is 1:2. So 1 mole of CH4 needs 2 moles of O2.
