of octane had been converted to carbon dioxide CO₂.
Octane has a molar mass of
1.000 gallon of this fuel would have a mass of 2.650 kilograms or , which corresponds to
of octane.
Octane undergoes complete combustion to produce carbon dioxide and water by the following equation:
An incomplete combustion of octane that gives rise to carbon monoxide and water but no carbon dioxide would consume not as much oxygen:
The mass of the product mixture is heavier than that of the octane supplied. Thus
of oxygen were consumed in the combustion. There are
of oxygen molecules in
of oxygen.
Let the number of moles of octane that had undergone complete combustion as seen in the first equation be (
). The number of moles of octane that had undergone incomplete combustion through the second equation would thus equal
.
25 moles of oxygen gas is consumed for every two moles of octane that had undergone complete combustion and 17 moles if the combustion is incomplete.
Therefore out of the 23.2 moles of octane had undergone complete combustion to produce carbon dioxide.