Talk:Gas laws

Merger proposal
I propose that Gas laws be merged into Gas. I think that the content in the Gas laws article can easily be explained in the context of Gas, and the Gas article is of a reasonable size in which the merging of Gas laws will not cause any problems as far as article size or undue weight is concerned. Katanada (talk) 07:33, 27 March 2011 (UTC)

I disagree. If we include everything about gas in the gas article it will get to large. I think it is better if we provide a short section and a link (as already exists with many other gas related topics). Modularity is great. — Preceding unsigned comment added by Youarefunny (talk • contribs) 15:57, 12 June 2011 (UTC)

I think that the articles should not be merged as the Gas article would become too large. Also, if a user is searching for Gas laws it would be harder for them to find the information if the article was merged. — Preceding unsigned comment added by Pineapple Head0000 (talk • contribs) 17:04, 11 July 2011 (UTC)

Other talk
Ideal gas and Gas laws are both currently stubs. They both deal with the same topic, as far as I can tell: Gas laws are laws of Ideal Gases, and Ideal Gases are hypothetical gases which obey those laws. Does anyone have objections to me merging the two & leaving one as a redirect? (and which one to choose as the main page?) -- Tarquin 04:59 Jul 30, 2002 (PDT)

Hmm... how about we axe everything under the summary? I mean, we really don't need brief summaries of two different random gas laws when there are individual entries for them. I think we should leave this up otherwise, because I think someone looking up "gas laws" wants a brief overview of various gas laws... maybe they're looking for one in particular, or wants to know the major ones. Have a link to ideal gases, sure, but not the whole page... anyway, my 2 cents. Lepidoptera 03:59, 16 July 2005 (UTC)

Potential Inconsistancy?
Is it a contradiction between this article, where:
 * p=const*T or p/T=const

and the Law of Charles and Gay-Lussac, where:
 * T/V=const or V/T=const

or am I wrong? First version presumes V=const, the second p=const. Could someone explain this to me in here? Excuse my language but it's not my native. C4 10:57, 6 May 2004 (UTC)

There's no inconsistancy. There are three laws: Charles, Boyle's, and Gay-Lassac. In Charles's law, you assume that pressure is constant, and V1/T1=V2/T2. In Boyle's law, you assume that temperature is constant, and P1V1=P2V2. In Gay-Lassac's law, you assume that volume is constant, and P1/T1=P2/T2.

Someone got the brilliant idea that you could combine all these individual laws into one law, called the Combined Gas Law, which states that (P1V1)/T1= (P2V2)/T2 Lepidoptera

The gas laws are valid only for special conditions and ideal gas behavior. Ideal gas properties (laws) operate only when attractions between neighboring gas molecules are small compared to their average kinetic energy. The volume of the space available has to be big compared to the size of the gas particles.

Boyles law, P1V1 = P2V2 is valid only when the temperature and number of mols of gas are constant.

Charles law V1/ T1 = V2/T2 is valid only when the number of mols of gas and the pressure are constant.

All of these describe what happens to a fixed amount of gas (constant mols) when one variable in the combined gas law is held constant.Moleculedoctor (talk) 20:34, 24 February 2009 (UTC)

Graham's law

 * Graham's law, named after Thomas Graham, states that the kinetic energy of two samples of different gases at the same temperature is identical.

I don't think that it says any such thing - see Talk:Graham's law. Cutler 13:38, July 14, 2005 (UTC)

Yeah, Graham's law is about diffusion... Lepidoptera 03:54, 16 July 2005 (UTC)

Boyle's Law
If an exhaust pump is connected to a fixed 100cm^3 flask, the volume of liquid swept out by the piston is 25cm^3 each stroke and the pressure in the vessel is originally 1 atm, what is the pressure in the flask after 2 strokes?

Homework question?

Please do not come on Wikipedia looking for help on specific homework. There's Wikianswers or other boards for this purpose.74.131.137.194 (talk) 23:58, 8 March 2011 (UTC)

Use of SI units
I think the article should be converted to SI units. The official unit for pressure is Pascal, not atmosphere. The unit for volume is m^3, not liters.

I defiantly agree. Also it says Kelvins where I'm pretty sure it is just Kelvin.

Disputed
Do the units even matter as long as they are persistence throughout the equation on which one uses for each of the three "things"? In other words, the article needs to mention whether the units have to be in those mentioned for the laws to work. I don't think they do. Bayerischermann 01:49, 7 June 2006 (UTC)


 * Quite right; I have made a suitable addition. --Runcorn 19:30, 7 June 2006 (UTC)

Indeed physical quantities, hence quantity relationship equations, are independent of units as long as you use a coherent system such as the SI. What isn't independent of units is the value of constants. 195.23.97.225 14:24, 26 April 2007 (UTC)
 * Yes, I think that the article already says that.--Runcorn 21:10, 26 April 2007 (UTC)

Hi, I've corrected 'amount' to 'number' in several places throughout this page. the rule of thumb: If you can count it, use 'number'; if you can weigh it, use 'amount'. Steev (talk) 23:58, 14 October 2011 (UTC)

Clarification of purpose?
The lead implies that the article is describing the historical "gas laws" rather then a detailed treatment of the laws themselves - better placed elsewhere. Have tidied up a bit to emphasise this. Pdch (talk) 12:59, 1 January 2008 (UTC)

Avogadro's law mistake
There is a mistake in Avogadro's law, says P1/T1=P2/T2 when it should have mole number, not temperature, and should probably have a fancy-pants image for the equation like all the other sections. I don't have the expertise or impetus to make it look nice, so I'll leave it to someone who is actually a legitimate Wikipedia editor instead of a random guy, so I thought I'd just point it out here. — Preceding unsigned comment added by 131.215.6.227 (talk) 05:21, 4 December 2011 (UTC)

Combined and ideal gas laws: k5
What's the meaning of k5? Could somebody clarify this in the text? Wikispaghetti (talk) 12:16, 3 September 2012 (UTC)

It's a constant, named "constant 5". Usually, when teaching Gas Laws, you are dealing with many constants. So you use subscript to avoid confusion. As in: PV=K1, V/T=K2, etc.

The problem is that the article does NOT use this notation anywhere else. — Preceding unsigned comment added by 2001:1388:803:11F2:2C54:AF34:5759:9C8F (talk) 21:16, 10 December 2014 (UTC)

Conundrum: Inverse relationship between P and T
If I combine Boyle’s and Charles’ laws I get an absurd relationship.

(1) Boyle’s Law: PV=k1

(2) Charles’ Law: V/T=k2 or V=k2T.

Substituting for V in (1),

k2PT=k1 or PT=k1/k2, or P=k3/T. (Inverse relationship. Absurd!)

I would appreciate it very much if a person more learned than me would point out the error in this operation. --Prof. Bleent (talk) 16:12, 17 April 2015 (UTC)


 * Boyle's law only holds when T is constant, while Charles' law only holds when P is constant. In order for them to both hold at the same time, P and T must both be held constant.  So yes PT=k3 but only when both are held constant; varying either one violates that assumption.  Vaughan Pratt (talk) 02:00, 12 November 2022 (UTC)

Going beyond classical ideal gases
As the article currently stands, all the stuff only applies up to the classical ideal gas law. No attempt is made at handling the general ``gas laws". Hence, no Van der Waals equation of state, which is equally a valid gas law that one would think comes under this heading. I think a change in the name of this article and at least a hint and link to stuff beyond the simplistic classical ideal gas is both the cheapest way to handle this problem, and also in accordance with the reason of existence of this article. 42.60.85.76 (talk) 11:28, 3 November 2015 (UTC)