I've got another Brainteaser, but this time from the emissions group...A person fills his/her SUV’s 20 gallon tank with gasoline. The density is .8g.How many grams of CO2 would be created from 20 gallons of gasoline?

The question is unsolvable. If the combustion is not complete, CO or even Carbon atom rather than CO2 will produce.If combustion is complete, we calculate how many carbon atoms exist in 20 gallons of Gasoline. Assume all the carbon atoms can be converted into CO2. From there, we can obtain the weight of CO2.

a generic saturated hydrocarbon is C(n) H(2n+2) which produces n CO2 and n+1 H2O molecules on burning. assuming:(a) the hydrocarbons present are either saturated or don't have too many double/triple bonds(b) they are complex which means n is high(c) burning is almost complete then we can see that there is about 1 carbon atom for every 2 hydrogen atoms. so C is 12/14 by weight of gasoline.Now 1 gallon = 3.8 litres => 3.8*800 g = 3040 g, so 20 gallon = about 60kg of gasoline. weight of C should be about 60*12/14 kg = 51 kg approx. but when this gets converted to CO2, the weight of O2 is added and so this becomes 51 * (12+2*16)/12 = 51*44/12 = 187kg.on the other extreme, suppose all of gasoline was benzene C6H6. then the molecular ratio will be C:H = 1:1 and weight ratio is 12/13. this shouldn't make much difference to the calculation. in otherwords, condition (a) is not very important.so, i believe the answer should be about 187 kg which is 187/0.45 lb = 416 lb approx.it does seem quite a bit of CO2 to unleash with just one full tank... (edited)

QuoteOriginally posted by: needaclueso, i believe the answer should be about 187 kg which is 187/0.45 lb = 416 lb approx.it does seem quite a bit of CO2 to unleash with just one full tank... I think you've just put your finger on the crux of CO2 pollution issues!It seems about right, a quick sanity check is that the CO2 release should be about 3 times the weight of the fuel.Now for your next trick, how long would it take a human to exhale an equivilent amount?

I'm not certain these are bang on but from memory;a) we breath about 1Hz (ish)b) lung capacity is? about 0.5L for normal breathingc) exhaled air is about 4% CO2d) inhaled air is about 0% CO2 (0.04% actually?)so we exhale 0.02L of CO2 per second, which is 0.00083 mol of CO244g = 1 mol CO2So 0.0367g of CO2 per secondSo the tank of fuel produces as much CO2 as a human in 5,100,000 s = 59 days

i guess it's worth noting that humans and other living things are part of the natural carbon cycle so the CO2 they produce is not really an excess.

good point needaclue, and of course when we bury people we are laying down oil reserves for the future