How much CO2 produced by burning one barrel of oil?

Answer 1

For the oil
Mineral oil has a density of around 0.8 g/cm3, "good" crude oil of around 0.8 - 0,83 g/cm3 and "heavy" crude oil is above 0,92 g/cm3

Crude oil consists (by weight) of 83% to 87% carbon.

One barrel is about 159 liters. Assuming a density of 0,85g/cm3 for our oil we would end up with 135 kg of oil, which contains on the higher end (87% carbon) 118 kg of carbon.

For the carbon dioxide:
Carbon Standard atomic weight: 12.0107(+/- 0.00008) g·mol−1
Oxygen Standard atomic weight: 15.9994(+/- 0.00003) g·mol−1
Lets say: Carbon = 12 and 2 x Oxygen = 2 x 16 = 32 => Total: 44
(12/44 = 27.27% of Carbon in CO2)

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Assuming that all the carbon will find its oxygen to form CO2, that would be 433 kg of carbon dioxide.

With above assumptions:
1 barrel of oil could produce 433 kg of carbon dioxide.
(Ignoring all other side products)

Sources:
http://en.wikipedia.org/wiki/Oxygen
http://en.wikipedia.org/wiki/Carbon
http://en.wikipedia.org/wiki/Mineral_oil
http://en.wikipedia.org/wiki/Crude_oil
http://en.wikipedia.org/wiki/API_gravity#Classifications_or_grades