Carbon, Hydrogen, and OXYGEN: Why didn’t someone tell me?

Posted: March 7th, 2009 | Author: admin | Filed under: environment, sketches | Tags: , , , , , , , , , , | 6 Comments »

I recently read that burning one gallon of gasoline releases about 19 lbs of carbon dioxide.

The mass on either side of a chemical reaction must balance, so I thought to myself, “If a gallon of fuel weighs 6 lbs, where is the other 13 lbs coming from?”

Well, it turns out that the additional weight is from the 21 lbs of oxygen that your car sucks from the atmosphere to burn that gallon of gas! Your car also spits out one gallon (8 lbs) of water in the process. 21 lbs of oxygen fills about four phone booths (~250 cu. ft.), and 19 lbs of carbon dioxide fills about two and a half phone booths (~150 cu. ft.). If your fuel economy is 25 mpg, then the above quantities occur every 25 miles you drive.


Here’s a simple mass equation:
C8H18 + (25/2) O2 = (8) CO2 + (9) H2O
hydrocarbon + oxygen = carbon dioxide + water

Basically, each Carbon atom broken from a fuel molecule grabs two Oxygen atoms from the air, and every two Hydrogen atoms grab one Oxygen atom from the air. Breaking these bonds yields heat energy.

Is this surprising to anyone else?
Disclaimer: As this not my area of expertise, I make absolutely no guarantees regarding the accuracy of this very simple example. The real-world process of combustion involves many variables.

6 Comments on “Carbon, Hydrogen, and OXYGEN: Why didn’t someone tell me?”

  1. 1 Dad said at 9:31 am on March 8th, 2009:

    the scaling is worth doing to get the air volume across, but the booths are not bad

    Sub – out the blue V and put in a silver c’vert

  2. 2 admin said at 11:16 am on March 8th, 2009:

    you don’t think the bright blue coupe matches the aesthetic nicely? hmmm.

  3. 3 admin said at 11:16 am on March 8th, 2009:

    Viggen ‘Verts are rare you know

  4. 4 tom said at 11:52 am on March 8th, 2009:

    two links from 2006 about this
    http://www.slate.com/id/2152685
    http://www.terrapass.com/blog/posts/how-to-turn-8-p

  5. 5 Vanessa said at 11:54 pm on March 8th, 2009:

    I like this much better than just hearing about the equation :) Agree with your dad that scaling the phone booths would drive the point home (really no pun intended…)

  6. 6 Yvonne said at 8:28 am on March 17th, 2009:

    also change the gas jug to one of those little red emergency refill ones with a black spout – at first glance it looks same as water and doesn’t communicate as well.

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