CO2 in Tire

[DGXSER]

That's what the dealers are filling the tires with nowadays. I saw big labels on the tires at my local Saturn dealer a while back, and kinda wondered how someone was supposed to re-fill their tires if they get low... I've never seen a "Free Nitrogen" sign at the corner gas station. Air works fine for me...

Actually, NOS is Nitrous Oxide. It is different than straight Nitrogen. But you won't find either at the corner gas station. You can probably get it pretty darn cheap at the local place that fills your helium balloons though. It is an inert gas and it is used all the time to purge out piping systems before adding whatever gas you will be using in it. It does displace oxygen form the system, so it is used to purge out metal containers for long term storage as well like heat exchangers and such. You could use it to seal your gas tank for long term storage and it will not rust if it is empty. (Knew I could tie it back into motorcycles somehow).

[oseaghdha]

Tru, Dat

Sorry Brian, but this statement is WRONG. ANY gas WILL expand and increase pressure when heated. That is physics in action! Nitrogen works for race cars because of the heat they produce. On the everyday street tire, IF you keep them properly inflated, it makes NO DIFFERENCE! It DOES make the tire companies a BUNCH more money, though! Marketing can be an income monster some times!

Boyle's (simplified) law is:

PV=T


Where P is the pressure and V the volume. T is the temp.

Since V remains the same, when temp goes up pressure must increase as well.

PHYSICS/OFF

[trbig]

The main deal with the nitrogen in tires is that the nitrogen molecules are much larger than oxygen molecules. Over time, the oxygen molecules seep through the tires, leaving the nitrogen, and a slightly low tire. The nitrogen is supposed to help under extreme heat situations, but they talked of the extreme conditions... being tires for aircraft as they go from zero to 200 mph or so instantly.

What I find humerous though, is the cost of getting the tire filled with "nitrogen", when the air you are breathing is approximately 79% nitrogen already. So theoretically, every time you have to refill a tire, what's left in the tire should be mostly nitrogen already since the oxygen molecules seep out first. Can you say "Scam" boys and girls?


Tod

[oseaghdha]

Chemist in the house?

The main deal with the nitrogen in tires is that the nitrogen molecules are much larger than oxygen molecules. Over time, the oxygen molecules seep through the tires, leaving the nitrogen, and a slightly low tire. .......................


Tod

Yeah I've read that in several places.
But I don't get it because N is Atomic Number 7 and O is Number 8. Meaning that Oxygen has one more proton, and this is demonstrated in the atomic weights: 14 and change for N vs almost 16 for O.

I believe both elements generally are diatomic (N2, O2) in the wild.

So how is N a bigger molecule?

It may come down to the propensity of Oxygen to combine with other things, like steel, aluminum, and rubber. Nitrogen is inert, as was pointed out up thread.

[TopCatGr58]

Didn't you guys pay attention in Chemistry class??

Hey folks,

I'm with TOD is it's fairly useless to try to use pure Nitrogen. Secondly, Nitrogen is NOT INERT!! I'm not a chemist, but I do remember a bit from my high school classes...if you look at it on the periodic table, it's 3 positions from the far right....and the far right column IS the NOBLE INERT gases of Helium, Argon, Neon, Krypton, Xenon, etc.!!! Their outer electron shell is FULL, the first layer only needs 2, then the next is 8, and multiples of 8...which is a full electron shell layer! Nitrogen is only 7, 2 inner and 5 outer, needing 3 more to fill it, so it CAN and DOES react with other elements to share/combine electrons to fill it's outer shell to a value of 8.

The reason why Carbon is so strong, is that it needs 4 to fill it's outer shell, and when it combines with other carbons, it has a VERY STRONG bond sharing 4 electrons with other carbons also sharing 4 electrons, etc...!

When I was needing to weld my aluminum saddlebags, I had to use PURE ARGON gas for a shielding gas to keep oxygen and nitrogen from getting to the molten aluminum.
T.C.

[oseaghdha]

Hey folks,

I'm with TOD is it's fairly useless to try to use pure Nitrogen. Secondly, Nitrogen is NOT INERT!! I'm not a chemist, but I do remember a bit from my high school classes...if you look at it on the periodic table, it's 3 positions from the far right....and the far right column IS the NOBLE INERT gases of Helium, Argon, Neon, Krypton, Xenon, etc.!!! Their outer electron shell is FULL, the first layer only needs 2, then the next is 8, and multiples of 8...which is a full electron shell layer! Nitrogen is only 7, 2 inner and 5 outer, needing 3 more to fill it, so it CAN and DOES react with other elements to share/combine electrons to fill it's outer shell to a value of 8.

The reason why Carbon is so strong, is that it needs 4 to fill it's outer shell, and when it combines with other carbons, it has a VERY STRONG bond sharing 4 electrons with other carbons also sharing 4 electrons, etc...!

When I was needing to weld my aluminum saddlebags, I had to use PURE ARGON gas for a shielding gas to keep oxygen and nitrogen from getting to the molten aluminum.
T.C.

You are right TC, it is not trully inert, but N2 is fairly unreactive esp. when compared to O2.

Although it does work good in beer!