How Big Is Your Footprint?

Have you ever stopped to wonder how much waste you generate?  Just out of curiosity, I wondered to myself today how much waste I put out driving back and forth from college.  Now don't get me wrong, I'm no economist, but the results astounded me.

Here's how my calculations went:

My vehicle holds about 20 gallons of gasoline.  Gasoline is comprised mostly of octane, or C8H18. (Yes, there are other hydrocarbons, alcohols, functional groups, and such in there, but it's pretty well represented just by octane.) The balanced equation for the combustion of octane is as follows:

2C8H18 + 25O2 →16CO2 + 18H2O

We'll say that gasoline has about the same density as water, or 1kg per liter.

So here's the math:

20 gallons x (3.8 liters per gallon) = 76 liters of octane

76 liters x (1kg per liter) = 76 kg of octane

76 kg x (1000 grams per kg) = 76,000 grams of octane

Using the molecular weight of octane,
76,000 grams x (1 mol per 114.224 g) = 664.21 mol (this is a measurement of how many molecules of octane are being burned. 1 mol = 6.022*1023 molecules.)

For every molecule of octane burned, 17 molecules of exhaust are produced. So,
664.21 mol of octane x (17 mol of exhaust per mol of octane) = 11291.57 mol of exhaust.

A mol of gas (like exhaust) at standard temperature and pressure (i.e. normal conditions) takes up 22.4 liters of volume. So,
11291.57 mol of exhaust x (22.4 liters per mol) = 252,931.168 liters of exhaust.

TWO HUNDRED FIFTY-THREE THOUSAND LITERS OF EXHAUST from one tank of gasoline.

Maybe tomorrow I'll ride my bike.