How is it possible that a gallon of gas emits 19.4lb of CO2?

Question

A gallon of gas isn't even 7 pounds. How is it possible that the CO2 emissions can be almost three times that?

(Source: http://www.epa.gov/otaq/climate/420f05001.htm)

Answer 1

Because when you burn carbon you have the reaction

C+O2 ---> CO2

for 12g of carbon burned , you have 12+2*16 = 44g of CO2

44/12=3.66 the weight of CO is 3.66 more than carbon

Answer 2

Your forgetting to include the weight of the O2 that is reacting with gasoline. Now gasoline is a mixture of hydrocarbons ranging from chains with 6 carbon atoms to chains of 12 carbon atoms. Keeping things simple lets say the only products formed from burning gasoline are CO2 and water. Each carbon in the chain reacts with to O2 to form CO2. Now each Carbon atom weights 12.01 atomic mass units (amu), and each O atom weights 16 amu with a total of 32 amu of O2 reacting. If we keep things simple still basically means if you burn 12 pounds of gasoline you'll produce 44 pounds of CO2 pounds.

Answer 3

Perhaps the gas is compressed? That may explain the large mass of CO2 produced from a small volume.

Answer 4

Whoa thats a good one.....maybe Al Gore's claim of 70 million pounds of CO2 a day is a little high then?

By the way, I couldn't get that link to work, maybe EPA is reading this and discovered they were off just a little.

Answer 5

Yes. Say it's all octane C8H18 MW = 102g/mole

7lb = 3175g = 31.12 moles (*8) = 249 mole CO2 (8 mole CO2)=10,956 g CO2
=24lb CO2