Can Burning One Gallon of Gasoline Really Release 21.1 lbs of Carbon?

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Discussion Overview

The discussion centers around the claim that burning one gallon of gasoline releases 21.1 lbs of carbon, exploring the chemistry of combustion, the weight of gasoline, and the implications of these figures. Participants examine the relationship between the weight of gasoline, the carbon content, and the role of oxygen in combustion, with a focus on the accuracy of government claims regarding carbon emissions.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant questions the validity of the claim that burning one gallon of gasoline releases 21.1 lbs of carbon, suggesting it contradicts the weight of gasoline itself, which they estimate to be about 6 lbs per gallon.
  • Another participant explains that burning gasoline requires oxygen, and during combustion, hydrogen bonds with oxygen to form water, while carbon bonds with oxygen to form carbon dioxide, indicating that the mass of combustion products includes both the fuel and the oxygen from the air.
  • A different participant clarifies that the Department of Energy's claim refers to carbon dioxide, not carbon, and provides a calculation showing that the carbon content in CO2 accounts for about 12/44 of its mass, leading to an estimate of roughly 2.6 kg of carbon emitted per gallon of fuel.
  • One participant emphasizes the importance of considering the mass of oxygen needed for combustion, suggesting that the claims about carbon emissions are reasonable when factoring in the total mass of combustion products.
  • Another participant disputes the initial estimate of gasoline's weight, stating that gasoline weighs 8.6 lbs per gallon and calculating that this results in approximately 7.25 lbs of carbon, leading to a conclusion that aligns closely with the 21 lbs of CO2 mentioned in the article.

Areas of Agreement / Disagreement

Participants express differing views on the weight of gasoline and the validity of the carbon emission claims, with no consensus reached on the accuracy of the initial claim regarding the weight of carbon released from burning gasoline. Multiple competing perspectives on the chemistry of combustion and the calculations involved remain present.

Contextual Notes

Some participants rely on specific assumptions about the composition of gasoline and the combustion process, while others challenge these assumptions. The discussion includes varying estimates of gasoline weight and carbon content, as well as differing interpretations of government data.

thetexan
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Please look at this article...

http://www.dailymail.co.uk/news/art...th-Day-emitting-375-TONS-carbon-dioxide.html\

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?

tex
 
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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.
 
thetexan said:
According to the Department of Energy burning one gallon of fuel releases 21.1 lbs of carbon.
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.
 
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?
 
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:
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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