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Isnt this a bogus claim?

  1. Apr 22, 2014 #1
    Please look at this article...


    Gasoline weighs about 6lbs per gallon. According to the Department of Energy burning one gallon of fuel releases 21.1 lbs of carbon. How is this possible?

    That would be getting something for nothing wouldn't it. In no case will you get more than the component weight of carbon in the gas molecule, right. So it couldn't be more than 6 lbs of carbon released and probably much less than that...proportional to the amount of carbon atoms in the molecule.

    Isnt this a bogus government claim that supports their agenda? In fact, what would be the amount of carbon in a gallon of gas?

  2. jcsd
  3. Apr 22, 2014 #2
    When you burn the gasoline, you require oxygen. Gas is a hydrocarbon. When it is burned, the hydrogen bonds with oxygen in the air to form 2(H20), and the Carbon bonds with O2 to form CO2. There is a lot of air required to burn one gallon of gasoline.
  4. Apr 22, 2014 #3


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    Gold Member

    It doesn't say that. It says carbon dioxide.

    Carbon makes about 12/44 of CO2 by mass. That gives roughly 2.6 kg of carbon emitted per 3.8 litres of fuel as per the USDoE source(http://www.eia.gov/environment/emissions/co2_vol_mass.cfm).

    Assuming the jet fuel is kerosene, 1 gallon makes about 3kg. Kerosene is C12H26, with carbon making up roughly 144/160 by mass.
    The end result of complete burning of 1 gallon of kerosene is ~2.7 kg of carbon released to be bound with oxygen to form CO2. Looks like it's about right.
  5. Apr 22, 2014 #4


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    Staff: Mentor

    What does it mean to "burn" something?

    What is the other thing - apart from fuel - that is required for a combustion engine to work?

    Hint: will the combustion engine work under water?
  6. Apr 22, 2014 #5
    When you factor in the mass of oxygen needed for the fuel to undergo a combustion reaction the claims in the article seem to be reasonable. It is the carbon(and hydrogen) in the fuel and the oxygen drawn in from the atmosphere that contribute to the weight of combustion products (mainly carbon dioxide and water) produced.
    Last edited: Apr 22, 2014
  7. Apr 24, 2014 #6
    Gasoline's weight ( mass) is mostly from the carbon it contains
    I disagree with your 6 pounds - gasoline I buy here in Maryland weighs just 8.6 US pounds per gallon.
    So for rough math, 8.6 pounds of gasoline is almost 7.25 pounds of carbon (about 84% by weigh)
    When used as in burned ( think about the cars engine) it combines with a lot of oxygen from the air
    There they are talking about CO2 - 1 carbon atom combined with 2 oxygen atoms
    Oxygen weighs a little more than carbon, but for here we will use the same . so simple simple math - 7.25 times 3 is 21.75
    Close to the 21 pounds of CO2 in the article.
    It also makes 1.5 gallons of water ( ever notice the puddle of water behind a tailpipe of a idling vehicle?)
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