Talk:Ideal gas law
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[edit] Noting that PV=nRT is an approximation
I think it would be very helpful to change the equality to an approximate equality. Denoting that the law only works for ideal gases is important - because some people somehow never fully understand what "ideal" means. Being still a student - I find the use of approximations taught to kids as being truths is uterly ridiculous. People should learn what is and isn't an approximation - and then if they care, they can look up the more accurate equations. Fresheneesz 08:00, 21 November 2005 (UTC)
I respectfully disagree. The gas constant R is known with many significant digits. If you change some of these digits the formula is still approximately true, but not exactly true. So PV=nRT is more than an approximation. It is exact in the limit. Bo Jacoby 10:06, 21 November 2005 (UTC)
Ideal Gas is hypothetical and does not exist in any form in reality and therefore the Ideal gas law is an approximation. "The approximation breaks down at high pressures and low temperatures, where the intermolecular forces play a greater role in determining the properties of the gas." taken from [Ideal gas]. It is important to note that the ideal gas law is accurate but not precise. Physics is a description/approximation of reality, it is not a prescribed rule. Furthermore most laws and theories are unable to account for a number of physical phenomenons. --ANONYMOUS COWARD0xC0DE 05:12, 29 November 2006 (UTC)
- Seems I didn't completely read the first statement now that I look at it again. I have to agree with Bo Jacoby, although the equations approximate reality the equations are themselves exact. That said it is still important to note that ideal gases are approximations of reality. So I will compromise by adding the statement "a hypothetical gas" (same wording from Ideal_gas) after the first use of the phrase "ideal gas". --ANONYMOUS COWARD0xC0DE 06:03, 23 December 2006 (UTC)
[edit] Name: Universal gas equation
I changed the name of the article from Universal gas equation (UGE) to Ideal gas law (IGL) for the following reasons:
- IGL is in much wider use than UGE. For proof of this, a search of "universal gas equation" on http://scholar.google.com yielded one hit (and that was in a farming education manual), while a search of "ideal gas law" yielded 3,110, and it's used in every thermodynamics textbook I've seen.
- The IGL isn't in fact "universal". There isn't anything universal about it, because it's a simplification. In fact, no gas actually follows it, just an imaginary ideal gas.
COGDEN 01:05, Nov 19, 2004 (UTC).
[edit] Derived n
Is n=(PV)/(RT)?
Someone should put up the derived formulas for n,P,V,R, and T. That would help a lot.
--
Why? The equation is ridiculously simple as it is - finding any of the five just involves some very simple algebra. It would just clutter the article to state them explicitly. --193.11.221.16 09:51, 5 Jan 2005 (UTC)
the pressure needs to be in atmospheres, not pascals.
No. The SI unit for pressure is the pascal, not the atm. The formula nR=PV/T shows that actually there are two SI units of measurement for amount of substance: nR measured in J/K, and n measured in mol. The gas constant R is the conversion factor, telling how many J/K make one mol. Bo Jacoby 00:12, 20 February 2007 (UTC).
[edit] Edit by 134.82.125.70
Please log in to identify yourself. I do not agree that the preferred unit of pressure is the atm, because the SI says pascal. I don't think that the values of the gas constant should be quoted here because it has an article of its own. The inaccuracy of the gas law should not obscure the fact that the gas law determines the gas constant with many significant digits. It is more than just an approximation: It is asymptotically exact. The statement: At high temperatures, there are high energy collisions between particles, making intermolecular forces seem negligible, is not true. Even a single molecule constitutes an ideal gas. Bo Jacoby 08:56, 5 December 2005 (UTC)
[edit] Rewrite
I went ahead and rewrote everything in LaTeX. I removed the references to 
because that information is more relevent in a discussion of 
. Also, I don't know who wrote the passage about the ideal gas law not covering condensation and thus being less accurate than the Van der Waals equation. The correct reasoning is on the page now.
Let me know if there's something missing or incorrect. Cheers! Isopropyl 05:51, 2 March 2006 (UTC)
[edit] Added alternate forms
I added the alternate forms section, showing the common derivations using molar mass, or specific gas constants. Also, I made note that the temperature has to be in K or R... That's something that always nips me when working with this. KMossey 03:28, 8 June 2006 (UTC)
- the other parameters need to be in terms of R too, if you are a fan of R. maybe a comment to that effect needs to be added? Xcomradex 03:31, 25 July 2006 (UTC)
[edit] Hard-sphere gas is not an ideal gas
The hard-sphere gas is, in fact, a much-analyzed non-ideal gas. It probably deserves an article of its own. It should *not* be confused with the ideal gas.
