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Former good article nominee Gas was a good articles nominee, but did not meet the good article criteria at the time. There are suggestions below for improving the article. Once these issues have been addressed, the article can be renominated. Editors may also seek a reassessment of the decision if they believe there was a mistake.
Article milestones
Date Process Result
February 26, 2008 Peer review Reviewed
February 27, 2008 Good article nominee Not listed
Current status: Former good article nominee
Wikipedia CD Selection
WikiProject icon Gas is included in the Wikipedia CD Selection, see Gas at Schools Wikipedia. Please maintain high quality standards; if you are an established editor your last version in the article history may be used so please don't leave the article with unresolved issues, and make an extra effort to include free images, because non-free images cannot be used on the DVDs.
edit·history·watch·refresh Stock post message.svg To-do list for Gas:

Here are some tasks awaiting attention:
  • Cleanup : *Random grammatical errors that haven't been found.
  • Expand : *Lead Section to avoid confusion with plasma. See: Wikipedia:Lead section.
    • Summary of Kinetic Theory under the Microscopic section.
    • Wikify : *Bulleted list of simplified gas models. Make sure to maintain clarity of the list of assumptions made for each model. If the message is lost that the models are actually models and not reality, then the purpose is lost.
    • Historical Synthesis section

Unsorted "Talk"[edit]

Uh, isn't 'gel' another state of matter?

Removed the following: "(Incidentally, these phases correspond to the four basic elements distinguished in Antiquity: earth (solid), water (liquid), air (gas) and fire (plasma))." That's just silly. It's incredibly anachronistic (do you honestly think the ancient Greek had knowledge of plasma?) and it's not even technically correct - the four elements are made up of four properties - hot, wet, dry and cold, which arguably correspond far more closely to the states of matter anyway.

I think there should be a link to four elements somewhere, either in this article or in the disambig page. Something like "Gas is one of the four classical elements". --Stevage 14:21, 3 December 2005 (UTC)
But it's not one of the four classical elements! (unsigned, anon)
That's...a good point. Stevage 21:02, 4 December 2005 (UTC)

Can you tell me about why the gas prizes are so high?

See Gasoline - JM 12:50, 25 August 2005 (UTC)

More about use?[edit]

Shouldn't there be a section about the use of gas here, the growing importance of gas (for instance for heating etc.) and domestic uses? --Vikingstad 23:45, 21 November 2005 (UTC)

Ah, nevermind, I suppose the See Also link to Natural Gas is good enough... --Vikingstad 23:50, 21 November 2005 (UTC)

water vapor[edit]

1st para: "which will then boil or evaporate to become a gas (e.g. water vapor)" Surely water vapour is not a gas, but particles of water suspended in air? Water in its gaseous state is Steam, an invisible gas which can only be produced under presure.

Water vapor is the gaseous form, usually used for conditions below the boiling point. Stream is water vapor at or above the boiling point. At least that has been my understanding. Thanks, Vsmith 13:12, 9 January 2006 (UTC)
The definition of gas versus vapour that I'm familiar with is that if a substance in a certain condition is above its critical point then it's a gas, otherwise it's a vapour. Hence steam coming out a kettle is vapour, but steam at the top end of a supercritical steam turbine is a gas. Haven't got time to have a proper look around but the page on critical pressures for gas will no doubt cover this. 21:23, 2 May 2007 (UTC)

Definition of gas[edit]

The article lacks a more precise definition of gas (i.e. how can I know if a substance is in a gas state?). The article cites many properties of gases, but does not say which of them (if any of them) completely characterizes a gas. I don't know if there is a generally accepted definition, in case there is more than one we could write a discussion paragraph comparing them. I've seem somewhere that gas is a state where matter occupies any container. That is a very simplistic one (and formally wrong, I believe), does someone know a more technical definition? I like the fire article, maybe we could use it as a parameter for quality. Rend 01:06, 20 April 2006 (UTC)

agreed this article after 4 years is still lacking a definition as a student i will refrain to edit this article my sell for somebody who may have more experince in this topic also it would help if this article was styled like the the other states of matter IE luquid solid have really strong opening paragraphs24.113.207.119 (talk) 01:52, 21 September 2010 (UTC)

No intermolecular forces?[edit]

In the gas phase, the atoms or molecules constituting the matter basically move independently, with no forces keeping them together or pushing them apart.

I thought there still are intermolecular forces, but that these forces can be neglected in the gas phase, especially when the gas is considered as an ideal gas.

Why are the gas prices so high?[edit]

|. Because of all the energy there is know in this world and all the things are chanqeinq all the prices are qoinq uhp.!*''

Because Uncle Sam hasn't really done much in the search of alternative energy sources. How about solar 

power? Dont hear much about that, and the sun is on a stringent and dependant time schedule! Very dependable! Something is fishy. Forget the other countrys, center on America. Wait a second.... We are in debt and most our investors are foreigners... There is nothing we can do to become dependant because We would ween ourselves off the other countrys that are investing in this country. We will, as a group, never become independant with our own system of fuel... The saudis, or whoever owns the oil, own us.

How do I know this? Because many years ago, I devised a simple soulution for a diverse system of 

ecomical fuel supply partly involving the wind and sunlight. Shortly there after, some men in black came to my door and destroyed everything! My complex blueprints for a stronger America went down the

The conspiracy involves very rich people investing in other countrys. Mostly polititians, the people who

alledgedly work for the Americans in this country. The foreigners are supposed to be second to us. Maybe we just aren't vocalizing our concerns loud enough. The men in black told me, the real solution is easy, start riding a bicycle. I was so mad.

Common type of gases[edit]

Would flatus be considered a trace gas, or what? Or should it have its own listing under "types?" --Jay (Histrion) (talkcontribs) 20:05, 28 December 2006 (UTC)


Should it be 'gases', or 'gasses'? Theoretically, it should be the latter, since 'gases' should be pronounced 'gai-ses'. But I don't know. That should be in there somewhere, right? -Uagehry456|Talk 20:27, 12 April 2007 (UTC)

how many gases?[edit]

It seems that there must be a finite number of gases. For example at say atmospheric pressure and room temperature hexane is not a gas but methane is. So there are maybe 50 hydrocarbon type gases (including halogenated hydrocarbons, unsaturated ones etc.), and so on for elements such as oxygen etc.

So is there a list somewhere of all the gases which exist?

Just a dabbler 10:09, 30 May 2007 (UTC)

Gas does not "expand to fill whatever space it can"[edit]

If you spray CO2 from a fire extinguisher, does it fly out in all directions to fill the entire room? No, it pours out, lands on the floor, and forms pools. Gas only expands to fill whatever space it can if that space is a vacuum. [1]BRIAN0918 • 2007-06-08 14:51Z

Your observation is correct, but you are mistaken in your conclusion. A gas will expand to uniformly distribute itself in any container in the absense of any external forces acting on the gas. In the case of your observation, the external force is gravity. It does not have to be a vacuum for the gas to diffuse. Consider opening a small cannister filled with gasous nitrogen. Its density is extremely close to that of air, and so the force of gravity can be ignored since the nitorgen will be neutrally buoyant. In this case the nitorgen gas will expand until it is homogenously mixed with the rest of the air. CoolMike 21:28, 1 August 2007 (UTC)

The forces acting on gas particles are pretty complicated if you're gonna get all nit-picky about it. i guess if someone had some time, they could add some info to this article or link to another one. One thing about the Fire Extinguisher example is that different kinds of gasses(or gases) have different properties. And also, CO2 wil eventually mix into the atmosphere just like Nitro will, just might take a little bit longer for CO2 to do it. —Preceding unsigned comment added by ROBO HEN5000 (talkcontribs) 20:54, 24 September 2007 (UTC)

We need to get the addition of gas being affected by gravity into the article. Physics kooks are citing this article in support of their assertion that gravity doesn't affect gases or plasmas. Specifically, this phrase, "Finally, gas particles spread apart or diffuse in order to homogeneously distribute themselves throughout any container." There needs to be an addition of, "in the absence of external forces like gravity and air pressure." This needs to be corrected to ensure wikipedia isn't used to support crackpot theories. Trinioler (talk) 16:59, 3 January 2011 (UTC)

WikiProject class rating[edit]

This article was automatically assessed because at least one WikiProject had rated the article as start, and the rating on other projects was brought up to start class. BetacommandBot 09:52, 10 November 2007 (UTC)

Article Rewrite[edit]

Hi! I am currently re-writing this article so it makes more sense and is more "wikified". I am doing this as a 10-step process. while I complete this, please leave comments on this page until I'm done. Thanks! Katanada (talk) 05:28, 25 February 2008 (UTC)

STEP 1: Definition > COMPLETE
STEP 2: Characteristics > COMPLETE
STEP 3: Macroscopic Properties > COMPLETE
STEP 4: Microscopic Properties > NEEDS EXPANSION - Its currently "Stub-like"
STEP 5: "Gas Models" > COMPLETE
STEP 6: Special Topics > NEEDS EXPANSION - Its currently "Stub-like"
STEP 7: History > COMPLETE
STEP 8: References > COMPLETE
STEP 9: Clean-up > COMPLETE


The mass of a gas enters into the definition of specific volume, but apparently not elsewhere in the article.

A gas is 'ideal' at sufficiently low pressure, p. Then the fraction pV/T is proportionate to number of molecules of the gas, n. The constant value of the expression pV/nT is Boltzmann's constant. Deviations from the ideal state means that the number of molecules changes, due to condensation or to chemical reactions.

I suggest that the mass of the gas is treated late in this article. Mass is irrelevant in many applications.

Bo Jacoby (talk) 10:25, 26 February 2008 (UTC).

I'm currently editing from my phone so I'll keep it short for the moment and later finish. To answer the second part of your statement, I havent considered the mass of the gas. I agree that the mass is irrelevant so that's why its specific volume and not just volume. Specific volume is scalable for the amount of mass. Visit the NASA website on the reference list and read the section on density and specific volume. Katanada (talk) 14:08, 26 February 2008 (UTC)
I'm a little confused with the first statement you make. "A gas is 'ideal' at sufficiently low pressure, p." I'm not arguing it but I feel like theres two ideas in there that are a little confusing... a gas can act any which way it wants to at any given ambient conditions, whether under those conditions it follows the model stated by the "Ideal Gas" is a totally different thing. If we consider a "gas" as one model and an "Ideal Gas" as another then we can see where the two correlate (under what conditions they correlate). Whether they correlate more at "sufficiently low pressure" is fine but thats not what I'm trying to explain in the article. The model for an "Ideal Gas" has is own conditions and assumptions, thats the only thing I'm trying to display in the method of writing this article. Most people confuse the concept of an Ideal Gas and other simplifications of gases with the actual gas itself. Basically, I'm trying to have people say "This gas behaves as an Ideal Gas under these conditions" instead of "This gas is an Ideal Gas". I don't have any issue with your equations, I don't understand where that brings any more clarity to the statement. Katanada (talk) 23:28, 26 February 2008 (UTC)
Also, deviations from the "Ideal Gas model" is not necessarily just phase-changes or chemical reactions. I can theoretically squeeze enough gas into a container to where intermolecular forces would become significant enough to where the gas deviates from the ideal model. (this is just one example) Katanada (talk) 23:28, 26 February 2008 (UTC)

GA review[edit]

Symbol unsupport vote.svg

I quick-failed this article at GA because it seemed to have been submitted without reference to the GA criteria. It has no proper introduction (WP:LEAD), has no in-line citations, and does not conform to WP:MOS Jimfbleak (talk) 07:44, 27 February 2008 (UTC)

JamAKiska (talk) 22:52, 18 October 2009 (UTC) these notes have been incorporated into the main article and are no longer required.


Shouldn't the definition not contain the phrase "more or less random"? There is nothing random about the way particles in the atmosphere move, even if they can't be modeled in a real world application. Physics and calculus are quite capable of predicting the movement patterns of a small amount of an element in a gaseous state.-- Overdunn

I understand your point, although I'd like to point out one thing you said: "...movement patterns of a small amount of an element..." . This is one particular modelization of a gas. There are many different models that try to predict how gases/fluids move on the micro and macro scale. I have mentioned some of these models within the article (Extended hydrodynamics [this one is for rarified gases on the macro scale], and Navier-Stokes [moderate pressure gasses/fluids on the macro scale]) there are many others which are also mentioned in the article as far as particular molecular motion. If you feel the lead is unclear, it could maybe suggest that there are different models to different situations but I feel like that would detract from the general overview of the atricle... so I left it as "more or less" because we don't really know what happens, we just guess, and can statistically show 'more or less' what SHOULD be happening, given a set situation. If you want to discuss it further, let me know. I'd be glad to talk about it.Katanada (talk) 17:16, 29 September 2008 (UTC)

Uses of gasses?[edit]

This info is all great and everything, but what about how gas is used and how it affects us in our lives? How about for the rest of the species on the planet? Or on other planets? Where can you find certain gasses, and how are they useful or harmful? Are there gasses on, say, mars or the moon that can be mined and taken back to earth for new fuels? How about CFC's and other man-created harmful gasses? (careful not to be nature-biased on this. Even if nature is totally awesome, Wikipedia isn't the place) This article is far from complete, and very important. It's really just a bunch of stuff about how gas acts and gas' properties, which is fine for a portion of the article, but this article makes gasses seem fairly useless. G man yo (talk) 12:25, 17 November 2008 (UTC)

The focus of this article is as every other state of matter article and deals with the physical properties of gases as a whole. Katanada (talk) 19:37, 22 January 2009 (UTC)

Atomic Gas[edit]

I didnt check who suggested it -- but just a comment. maybe it would be good to have a reference posted on the atomic gas page before merging. I'm not sure that theres a whole lot of new information contained in the Atomic gas page though... opinions??? Katanada (talk) 10:28, 18 May 2009 (UTC)

It is an addition in terminology though -- so its probably good to include it here =] Katanada (talk) 10:29, 18 May 2009 (UTC)

If I am not mistaken, an atomic gas would be a noble gas or a highly reactive atom looking for partners like hydrogen that normally forms a covalent bond with another hydrogen atom (perhaps the reactiveness drops off at low temps). The new intro distinguishes between diatomic and compound molecules as well. The only new information provided by that article was the final line which could easily be pasted into the lead paragraph.

JamAKiska (talk) 13:48, 19 October 2009 (UTC)

Lead section now contains merged material from atomic gases.

JamAKiska (talk) 14:20, 19 October 2009 (UTC)
JamAKiska (talk) 14:27, 19 October 2009 (UTC) Merged content from atomic gases.


Smoke picture[edit]

Smoke isn't a gas. I suggest a caption change to e.g. "smoke particles show movement of atmospheric gas" (talk) (user:Totnesmartin at work, not logged in) 12:40, 17 October 2009 (UTC)

PS why are there two space shuttle pictures?

Thanks for the feedback. Hope the new caption is more to the point. I initially was looking for an image that illustrated the flow field of gases, along the lines of wind tunnels. While "smoke" has many negative connotations associated with it, in this case the use is reasonable. Another option would be to use a photo of tattle tails on a mainsail. I found the smoke image first. I'll switch the 1st shuttle photo for the sake of variety. A previous comment questioned the limitations of ideal gas laws. The first image illustrates the upper limit for the use of IdGL that aligns with most aero texts. The latter NASA image illustrates a flight regime in which computational fluid dynamics would be used to determine safety factors for the structural materials under loading in this image.

JamAKiska (talk) 14:58, 17 October 2009 (UTC)

inaccuracy on page.[edit]

A big inaccuracy in the first paragraph.

It's a common error to mix up ie and eg but they give very different meanings to a sentence. eg means "for example" and ie means "that is".

For example in the sentence:

A pure gas may be comprised of individual atoms (ie a noble gas or atomic gas like neon), elemental molecules made from one type of atom (ie oxygen), or compound molecules made from a variety of atoms (ie carbon dioxide).

This means that Oxygen is the only gas of elemental molecules and that carbon dioxide is the only gas from a variety of atoms. We know this is not true. Can someone who can unlock the page, correct this?

Could you take a look at the "real gas" section in the article to ensure I've used those latin abreviations correctly? Thanks... JamAKiska (talk) 13:27, 13 November 2009 (UTC) Adjusting article to proper use of latin abbreviations.

For reference:
"I.e." stands simply for "that is," which written out fully in Latin is 'id est'. "I.e." is used in place of "in other words," or "it/that is." It specifies or makes :more clear.
"E.g." means "for example" and comes from the Latin expression exempli gratia, "for the sake of an example," with the noun exemplum in the genitive (possessive case) to :go with gratia in the ablative (prepositional case). "E.g." is used in expressions similar to "including," when you are not intending to list everything that is being :discussed.
Katanada (talk) 15:50, 15 November 2009 (UTC)

In the section "Perfect gas", I found this: Perfect Gas equation of State (where n represents moles of a substance, all other terms see notation from Macroscopic section - Absolute temperatures and pressures apply)

   * Chemist version- PV = nRT
   * Gas dynamicist version- P = ρRT (note R in this expression has different units than the chemist version)

I could find no explanation of R anywhere on this page. c.pergiel ( (talk) 01:39, 21 November 2009 (UTC))

From Ideal gas: R is the gas constant (8.314 J·K−1mol-1 in SI units. Vsmith (talk) 02:29, 21 November 2009 (UTC)

Thank-you! Please take another look at this section for readability. I simply provided a link to the "gas constant" article to provide background material. JamAKiska (talk) 15:59, 23 November 2009 (UTC) /* Perfect gas */ Wikifying gas constant.

JamAKiska (talk) 16:26, 23 November 2009 (UTC) /* Perfect gas */ Tweaks for clarification and readability.
JamAKiska (talk) 12:57, 25 November 2009 (UTC) /* Perfect gas */ Tweaks for readability.

simplified model section[edit]

That section needs a going over, I'll do what I can but would love some help. As it is, there is a false distinction between Perfect gas and Ideal gas when they are really the same thing. The ideal gas is one made up of non-interacting point particles, and a real gas consists of an astoundingly large number of charged particles (lumped into what we think of as atoms and molecules) which obey the well-established laws of quantum mechanics when interacting with each other. There is a range of different levels of theory to which a real gas can be approximated. I think this is the direction this section should take. mislih 00:17, 5 May 2010 (UTC)

HAHA you want to bring up that argument again? lollllllzzz --- anyway .. the Real gas page has a bunch of models for it already. Gas just sort of introduces it Katanada (talk) 18:03, 5 May 2010 (UTC)
Go read "Elements of Gas Dynamics" by H. W. Liepmann and A. Roshko. Also read "Modern Compressible Flow: With Historical Perspective" by John Anderson. Otherwise, take a glance at Katanada (talk) 18:35, 5 May 2010 (UTC)
We should have something on the "Granular gas" model as well. We don't have anything at the moment. -- Derek Ross | Talk 20:26, 20 June 2010 (UTC)

Modified Introduction.[edit]

Try this adjustment to the introduction which is intended to broaden the appeal for the reader. I am sure the technical folks may want to adjust image locations and the like. Good luck...CUoD (talk) 00:57, 13 September 2010 (UTC)

See Also list needs trimming[edit]

More than half of them have no direct relationship to the subject at hand. Plus, the long list clutters and distracts. Could someone please start trimming the more unrealted ones? Thanks. Softlavender (talk) 08:29, 22 April 2012 (UTC)