How much CO2 is produced from a litre of petrol?
It seems improbable that a litre of petrol, which weighs about 740g, could produce 2.7kg of CO2 when burned. However, most of the weight of the CO2 doesn't come from the petrol itself, but from the oxygen in the air.
When petrol burns, the carbon and hydrogen separate. The hydrogen combines with oxygen to form water (H2O), and carbon combines with oxygen to form CO2. A carbon atom has a weight of 12, and each oxygen atom has a weight of 16, giving each single molecule of CO2 an atomic weight of 44 (12 from carbon and 32 from oxygen). To calculate the amount of CO2 produced from a litre of petrol, the weight of the carbon in the petrol is multiplied by 44/12 or about 3.7.
Since petrol is about 87% carbon and 13% hydrogen by weight, the carbon in a litre of petrol weighs 644g. (740g x 0.87).
We can then multiply the weight of the carbon (644g) by 3.7, which equals 2.7kg of CO2!
Imperial calculation.
