"basskisser" wrote in message
om...

That has absolutely nothing to do with the fact that that nitrogen
doesn't expand at the same rate as oxygen for any given temperature
change. Do you deny this?

Yes. I deny this.

Mr. Boyle denies this. Mr. Charles denies this. Mr. Gay and Mr. Lussac
deny this. They wrote laws of physics about it. Every chemistry, physics and
thermodynamics class uses these laws. Here, don't take my word for it, let's
take a look at some of the information available from the net.

As an example:

Department of Chemistry
California State University, Sacramento
http://kekule.chem.csus.edu/gaslaws

Boyle's Law
Simply stated, Boyle's Law indicates that for a fixed amount of gas (fixed
number of moles) at a fixed temperature, the pressure and the volume are
inversely proportional.
pV = constant or p1V1 = p2V2


In other words, as the pressure increases, the volume decreases. (When you
squeeze on a balloon to increase the pressure, the volume of the balloon
goes down.)



Charles' Law
Simply stated, Charles' Law indicates that for a fixed amount of gas (fixed
number of moles) at a fixed pressure, the volume is proportional to the
temperature.

V/T = constant or V1/T1 = V2/T2


In other words, as the temperature increases, the volume increases. (When
you heat a balloon the volume of the balloon goes up.)



Gay-Lussac's Law
Simply stated, Gay-Lussac's Law indicates that for a fixed amount of gas
(fixed number of moles) at a fixed volume, the pressure is proportional to
the temperature.
p/T = constant or p1/T1 = p2/T2


In other words, as the temperature increases, the pressure increases. (When
you put a pickle jar in the refridgerator, the drop in pressure from the
trapped air becoming colder makes it hard to open the jar later!)





Note that there is no factor in these equations for the type of gas. If you
take a rigid container that contains a gas, any gas and heat it up the
pressure will increase a known and predictable amount. You double the
temperature, you double the pressure.

These three laws combine together to create the "ideal gas" law, whihc is
PV=nRT. This law relates Pressure, Volume and Temperature. Give me the
starting values, how much you changed the other two variable and I can tell
you exactly what the third variable will be. I don't need to know what the
gases are involved.

The only time that you deviate from the ideal gas law is if you reach a
pressure/temperature point where the gas might change state into a liquid.
You had some basis for an argument with water at room temperatures, but
oxygen and nitrogen are not ever going to be liquid at any pressure you are
likely to have in your tires. Air will obey the ideal gas law as long as it
isn't saturated with water vapor, and as I pointed out earlier you would
have to try hard to get saturated air into the tires.

Rod