1. Gasoline is a remarkably interesting soup of hydrocarbons of various sorts, with bits of this and that added, but the average chemistry is not too far from being carbon and hydrogen, with two hydrogen atoms for each carbon. Burning involves combining gasoline with oxygen to make water and carbon dioxide. (Other things that are made in small quantities, such as carbon monoxide, are not as nice.)

The chemical formula for burning gasoline can then be written something like:

CH2+1.5 O2 --> CO2+H2O

(If you don't like having one-and-a-half oxygen molecules, you can think of two hydrocarbons plus three oxygens making two carbon dioxides and two waters; it is the same thing, really.)

In burning, each carbon atom, C, in gasoline eliminates two hydrogens and replaces them with two oxygens

each carbon atom weighs 12 atomic mass units
each hydrogen weighs 1
each oxygen weighs 16;

So, CH2 starts out weighing 14 (12 from carbon and 2 from hydrogen), and CO2 ends up weighing 44 (12 from carbon and 32 from oxygen)-the weight has more than tripled.

Rounding that off a little, the total weight of CO2 put out by a typical U.S. driver is three times larger than the weight of gasoline burned.

To get the number of pounds of CO2 per year from a typical car, then, multiply your answer from the previous question by 3.
A) 108,000 pounds / year
B) 216,000 pounds / year
C) 1,080 pounds / year
D) 10,800 pounds / year

2. Total Pounds (or Tons) of CO2 Produced by U.S. Drivers per Year Calculation:

Imagine for a moment that the CO2 behaved like horse ploppies, making a pile in the road, rather than wafting away in the atmosphere.

How much would we have?

Here are your necessary facts:

There are roughly 140,000,000 cars in the country
Each car averages 12,000 miles per year
Each car is producing @ 1 pound of CO2 per car per mile

How many pounds of CO2 are produced each year by U.S. drivers?

To get this number, simply multiply the 3 variables above for this answer. This is a big number - one that cheaper calculators won't be able to handle. In this case, you'll want to come up with the number of tons instead of the number of pounds of CO2 . (2000 lbs = 1 ton).

The formulas will look like this;

Total Pounds of CO2 produced in a year by U.S. drivers: # of cars X # of miles per car X pounds of CO2 per mile

Total Tons of CO2 produced in a year by U.S. drivers:(# of cars / 2000) X # of miles per car X pounds of CO2 per mile

-- or --

Total Tons of CO2 produced in a year by U.S. drivers: # of cars X (# of miles per car / 2000) X pounds of CO2 per mile

So, what do YOU come up with for this answer?
A) 1,680,000,000,000 pounds / year (or 840,000,000 tons )
B) 16,800 pounds / year (or 8.4 tons )
C) 16,800,000 pounds / year (or 8,400 tons )
D) 32,000,000,000 pounds / year (or 16,000,000 tons )

3. Pounds of CO2 per Square Foot of Road per Year Calculation:

There are about 15,000 square miles of paved roads in the U.S. (the roads are long and skinny, but if you took roads and made them into a giant tennis court, you'd have about 15,000 square miles), or about 15,000 x 5280 x 5280 = 420,000,000,000 square feet (rounding off just a bit).

For this answer, then, simply divide the answer from the previous question (number of pounds of CO2 per year produced by U.S. cars) by the total highway square footage number above.

Cheap calculators? You likely won't be able to type in the number of square feet; in that case, if you calculated a number of tons (T) in the previous question, you should do T x 2000 / 15,000 / 5280 / 5280, giving an answer very near to:
A) 0.004 pounds per square foot / year
B) 0.4 pounds per square foot / year
C) 0.04 pounds per square foot / year
D) 4 pounds per square foot / year

4. Now, imagine that instead of CO2, our cars putout horse ploppies that fell on the road. U.S. cars would be delivering the number of pounds of horse ploppies you just calculated, each year, to each square foot of paved road in the country. The CO2 from our cars, if turned to horse ploppies, would make a one-inch-thick layer spread across all the paved roads in the entire country each year.

Just take a moment and think of this-what would happen if you stomped on the accelerator in an inch of recycled hay? How about braking? After a few decades, would all the roads look like pickup-truck commercials, with giant sprays of something like mud coming off the tires? Would you enjoy being a pedestrian? Would joggers switch to cross-country skiing?

To get total U.S. CO2 production, you need to multiply again by about 3-we heat and air condition our homes, etc., as well as driving our cars, and most of the heating and cooling comes from fossil fuels, too. So, spread that inch of horse ploppies across your living-room carpet, and across every other living space in the nation. Put differently, the average American generates 22 tons of CO2 per year. (Compare this to a bit over half a ton per person per year of solid waste put out in garbage cans to go to landfills.)

With about 5% of the world's population, we are generating about25% of the world's CO2. If you had an inch-thick layer of horse ploppies each year on every square inch of paved road in America, you very clearly would smell it everywhere-the volatile organic molecules wafting off the mess would quickly be blown around the country and the world. We don't smell the CO2, but it is everywhere, building up steadily in the atmosphere, changing the climate... and we humans clearly are influential enough to do this.

So, for you alert readers playing along at home, how thick would the layer be if all the CO2 released by U.S. cars were converted to an equivalent weight of horse ploppies and spread uniformly across all the paved roads in the U.S.?(you've already seen this answer several times, actually, so for those paying attention, consider this your reward)
A) 1 inch
B) 1/10 inch
C) 1/100 inch
D) 1/1000 inch