Burning one gallon of gasoline produces 20 pounds of Carbon Dioxide or CO_{2}.
It seems paradoxical that a gallon of gasoline weighing 6.25 pounds (2.83 kg) can produce 20 pounds of anything but let's investigate that.
Gasoline (or octane) has the chemical formula C_{8}H_{18} or 8 parts carbon and 18 parts hydrogen.
Looking up the atomic mass  carbon is 12 and hydrogen is 1.
So, the molecular mass of gasoline is 12 × 8 plus 18 × 1 which equals 114.
Okay getting technical here, a mole of gasoline weighs 114 grams and a gallon of gas weighs 2,834 grams.
Therefore a gallon of gas contains (2,834 ÷ 114) 24.86 moles.
The chemical equation for the combustion of gasoline is:
2 C_{8}H_{18} + 25 O_{2} → 16 CO_{2} + 18 H_{2}O
Which can be rewritten as:
C_{8}H_{18} + 12½ O_{2} → 8 CO_{2} + 9 H_{2}O
This means that burning 1 mole of gasoline produces 8 moles of carbon dioxide.
Therefore, a gallon of gasoline (24.86 moles) produces 198.91 moles (24.86 × 8 = 198.91) of carbon dioxide.
And what is the mass of 198.91 moles of carbon dioxide? (Basically, what does it weigh?)
First we have to determine the molecular mass of carbon dioxide.
Atomic mass of O_{2} = 32 plus the atomic mass of carbon,12, equals 44.
So, the mass of 198.91 moles of carbon dioxide = 198.91 × 44 = 8,752 grams = 8.752 kilograms,
which converts to 19.3 pounds.
We can therefore say that burning 100 gallons of gasoline produces one ton of carbon dioxide!
