The anti-fossil fuel “save the world” from people ecowackos have correctly gauged that one gallon of gasoline (which weighs about 6.3 lbs) produces about 20 lbs of CO2. They base that on the fact that when gasoline burns carbon and hydrogen atoms separate. Hydrogen then combines with oxygen to become water and the carbon atoms combine with oxygen to become carbon dioxide. To calculate the amount of CO2 produced from a gallon of gas, the weight of the carbon atom (12) is added to the weight of two oxygen atoms (32) for a total weight of 44/12 or 3.7. Since gasoline is about 87% carbon and 13% hydrogen by weight, if we multiple the weight of carbon (5.5 lbs) by 3.7 we have about 20 lbs of CO2.
Okay, now that I fed you the boring stuff, here’s the interesting stuff. A single mature tree absorbs carbon dioxide at a rate of about 48 lbs per year, and releases enough oxygen back into the atmosphere to support two human beings. One acre of trees annually consumes about the same amount of carbon dioxide produced by driving a car 26,000 miles. That same acre produces enough oxygen to keep 18 people alive for a year .... http://www.conservativeactionalerts.com