wa8yxm
Wherever I happen to park
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Joined: 07/04/2006
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RamTX wrote:I don't believe CO2 is considered an inert gas by definition.
Where as I believe it is, and my degree is in Science
However it does not matter
That said www.powertank.com
Nothin adds excitment like something that is none of your business
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Aridon
SE Florida
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Why do people believe stupid things? Seriously, the size difference in O2 and N molecules is so small its not even worth considering. People want to feel better about spending $5 a tire to fill up.
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Chemgoddess1
Suburbs of Cleveland, Ohio
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It was my understanding that it was not size that mattered.....
N2 does not have the same heat capacity as O2, tires stay cooler therefore having less issues with thermal expansion while driving. Cooler means the molecules are not as active which means they are not migrating out of the tire as quickly. While this may be an issue for race cars and those doing a lot of driving in warm climates, it probably is not so much for the rest of us.
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BCSnob
Knoxville, MD
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I seriously doubt the difference in specific heat capacity of nitrogen (1.040 J g-1 K-1) and oxygen (0.918 J g-1 K-1) accounts for the difference in tire pressure changes with temperature. What is important is moisture content (water vapor: 2.080 J g-1 K-1) in the gas and possibly the reactivity of the gas (reactivity: oxygen > carbon dioxide > nitrogen). The main advantage of the air alternatives is the ease with which they are available with low moisture content and possibly the availability of them in liquid form (gasses compressed to liquid form take up less volume).
Mark (trained to pile it high and deep in chemistry)
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Mousefart
New Jersey
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tatest wrote:Chemgoddess1 wrote:Shearwater wrote:Nitrogen molecular weight (N2) = 28
Oxygen molecular weight (O2) = 32
CO2 molecular weight (CO2) = 44
Nitrogen molecules are NOT bigger than oxygen or CO2.
Ummmm....molecular weight has nothing to do with molecular size. Size of O2 is ~ 2.96 A, N2 ~ 3.16 A. It has to do with the electron energy an the size of its cloud.
So I guess all tires have been carefully designed to be 3.05 Angstrom osmosis membranes, so as to separate the molecules, and leak out only the oxygen?
Yes, it's a conspiracy to get us to buy Nitrogen of our tires!! 
Paul (Mouse)
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TAS
Baton Rouge, La
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I've got a CO2 set-up for my jeep and I love it. I like the portability of it. there ARE cheaper ways to air up. CO2 just seems to do it quicker than any 12V compressor I've ever used. I'm a very impatient person and I like thinks to happin quickly. Well...not that but, most everything else! lol
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Chemgoddess1
Suburbs of Cleveland, Ohio
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Mark, then why is this so prevalent (N2) in racing? I always thought it was that it keeps the tires cooler.
....not trained to pile it high and deep but have learned from the years of stepping in it!
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Cloud Dancer
San Antonio and Livingston TX USA
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Chemgoddess1 wrote:Mark, then why is this so prevalent (N2) in racing? I always thought it was that it keeps the tires cooler.
....not trained to pile it high and deep but have learned from the years of stepping in it!
The reason we used it in racecars is because the pressure remained constant, or more so than compressed air. In dirt Sprint Cars, the pressure was selected anywhere from 4 to 18 psi, in 1/2 psi increments, depending on racetrack traction character and moisture content. Therefore, constant pressure was an advantage.
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BCSnob
Knoxville, MD
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Cloud Dancer wrote:The reason we used it in racecars is because the pressure remained constant, or more so than compressed air. Were the temperature induced pressure changes less with nitrogen than with compressed air due to differences in moisture content or the lack of the other gasses (pure nitrogen vs. nitrogen/oxygen/argon/carbon dioxide)? Gases with low moisture content are readily available when produced from "pure" liquefied gases.
There were scientific instruments in grad. school that required a very low moisture content atmosphere in order to make proper measurements (for example: Michelson interferometer) and we used the nitrogen gas that boiled off a large tank of liquid nitrogen. This yielded nitrogen that had 0.000000002% moisture (20 ppb by volume).
Mark
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K3WE
Missouri
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wa8yxm wrote:RamTX wrote:I don't believe CO2 is considered an inert gas by definition.
Where as I believe it is, and my degree is in Science
However it does not matter
That said www.powertank.com
I think that the original poster is talking about the "noble elemental gasses" which are called noble because they are relatively inert, and yes, C02 is not an elemental gas.
And, I also think that "inert" is a relative term. Solid C02 sealed in a coke bottle at room temperature is pretty explosive.
(No degree in chemistry- just took a bunch of it).
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