Talk:Partial pressure

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	Portal This article is within the scope of WikiProject Physics, which collaborates on articles related to physics.
A	This article has been rated as A-Class on the assessment scale.
High	This article is on a subject of High importance within physics.
Help with this template Comments: edit – history – watch – refresh I have rated this article as being in Class A because it has all of the elements required for that class as described in the Assessment article. It is well written and has all of sections required by standard Wiki practice. However, I do feel it could still benefit from more improvement. It is of High importance to chemists and to chemical engineers. I cannot speak for its importance to Physicists. - mbeychok 05:45, 4 December 2006 (UTC)

[edit] Technical accessibility

This article could use some work to make it more accessible to people who are not already familiar with the principles of thermodynamics and kinetic theory. I'm sure that schoolchildren and even adults who haven't had basic science education would find the explication of fundamental concepts here to be quite helpful. I've already drafted similar improvements for Phase (matter) (see my 10 July 2005 edits there), which are illustrative of what I have in mind. -- Beland 13:29, 10 July 2005 (UTC)

Think I made it about as simple/accessible as it's going to get; just wanted to mention here that I removed the technical template from here as well as the main article (there was one here, on the talk page, for some reason) - Straker 20:26, 18 October 2005 (UTC)

I appreciate the effort of writing the article, however I agree it could be more approachable for a wider audience. That doesn't mean you have to remove any equations. Rather just add some clarifying examples.

For example, add to the first section something like this: "Earth's atmosphere is 14.7 psi at sea level, and is composed of 79% nitrogen and 20% oxygen. The partial pressure of oxygen is therefore 20% * 14.7, or 2.94 psi. The partial pressure of nitrogen is 79% * 14.7 or 11.61 psi."

Further you could illustrate this by saying: "Astronauts wearing space suits breath pure oxygen at 4.2 psi. Despite the low pressure, they have more breathable oxygen available than at sea level on earth. This is because the partial pressure of pure oxygen at 4.2 psi is just that -- 4.2 psi, whereas on earth at sea level the partial pressure of oxygen is 20% * 14.7 psi or 2.94 psi".

Suggest revising the last section about safe ppO2 ranges, since the actual safe range is a function of time AND ppO2. Humans can survive with less than 1 psi O2 for short periods without developing anoxia, and 90 psi pure O2 for short periods without developing oxygen toxicity. There's a nice graph you could probably get from this page to illustrate: [1] Joema 04:19, 25 December 2005 (UTC)

[edit] Biological Applications

Whilst this article is very well written and very fully instructed in the ideals of pressures and pressure gradients, it is missing something. I am thinking of the possibilty of a biological side to this topic. The ideas surrounding partial pressures of gases in the blood systems of animals allowing for transport and dissociation at tissues and the lungs. This is a relatively simple idea but one I think would greatly benefit this already good area of research. —Preceding unsigned comment added by 86.144.167.89 (talk • contribs) April 26, 2006 (UTC)

[edit] Needs quite a bit of editing

In my opinion, this article needs quite a bit of editing to make it scientifically and technically sound. It also needs to be consistent throughout the article (for example, it uses different notation in different sections, notably the section on diving breating gases). The categories to which it is assigned really need to be more appropriate. For example, the list of categories needs to include Category:Chemical properties. Also, there is very little thermodynamics involved in the article as it now stands.

Someone who is really experienced in physical chemistry needs to do some major revisions. I will make some of the more obviously needed changes today .. and I may return later to do some re-writing. - mbeychok 17:23, 24 May 2006 (UTC)

It took me a bit longer than I estimated a few days ago, but I have now completely re-arranged and hopefully improved this article. I believe it is now much more scientifically and technically correct. I not only re-arranged and re-titled some of the sections, I also eliminated some of the redundant material which is very adequately contained in other articles (see the links in the "See also" section). - mbeychok 22:44, 26 May 2006 (UTC)

[edit] How do you spell jargon?

J-A-R-G-O-N... make it easier to understand for the rest of us... --toaster 22:16, 27 September 2006 (UTC)

toaster, there are quite literally hundreds, if not thousands, of articles in Wikipedia that I find completely incomprehensible. For example: Quantum mechanics, atomic physics, Psycholinguistics, Generative linguistics, Algorithmic information theory, String theory, Cosmology, at least 75% or more of the Thermodynamics articles, and 90% or more of the advanced Mathematics articles, etc. etc. All of those subjects have arcane terminologies or jargons that are beyond my fields of knowledge.I just accept the fact that those subjects simply cannot be "dumbed down" enough for me to understand them unless I am willing to spend months or years of study to become familiar with them. None of us can know everything. - mbeychok 23:55, 27 September 2006 (UTC)

But all is not lost. With some short intro phrasing and use of metaphor, even highly technical articles can in theory be made somewhat accessable to intelligent layman, until you get to the math. See the Feynman physics lectures (and even more, his QED book) for a valiant attempt at this. Also books by Steven Weinberg and Leon Lederman. See technical writing for more on the problem. This is very difficult writing to do, since people who really know the subject often forget how much they know, and are used to years of shorthand use. Those who are in a better position to explain to laymen, often lack the actually rigorous tech understanding, particularly when the math gets upper-division. SBHarris 19:19, 8 December 2006 (UTC)

[edit] Henry's constant

why is henry's constant labeled as "k" instead of "H"? —Preceding unsigned comment added by 68.107.105.71 (talk • contribs) November 6, 2006 (UTC)

Just by convention ... although some books and other references do use H. However, as someone said, "a rose is a rose by any another name" if I got that quotation right??? mbeychok 19:02, 6 November 2006 (UTC)es

No. "Rose is a rose is a rose"-- Gertrude Stein. "What's in a name? That which we call a rose by any other name would smell as sweet." -- Romeo and Juliet/Shakespeare. H is not used for Henry's law because in chemistry it's already taken as the symbol for enthalpy, where the H no doubt is used because it signifies "Heat" (the same as enthalpy at constant pressure)-- a much more important concept. SBHarris 23:29, 18 June 2007 (UTC)

I just to know what is the relation between the henry's constant and temperature as well as the solubility of the given liquid?--59.95.203.103 17:28, 10 September 2007 (UTC)hetal shah

Hetal shah, to answer your comment, see the Henry's law article ... especially the section on Temperature dependence of the Henry constant. - mbeychok 18:34, 10 September 2007 (UTC)

[edit] Partial pressures in liquids are not the same as pressures that would obtain if the liquid vanished

The article text states:

In chemistry, the partial pressure of a gas in a mixture of gases or of a gas dissolved in a liquid is the pressure which that gas would have if all other components of the gas mixture or liquid suddenly vanished without its temperature changing.

This is true for ideal gases, but in general not true of liquids (nor does the ref given say it's true in liquids), and this fact is due to non-unity Henry's constants. Obviously, two different ideal gases at the same gas partial pressures have the same concentration, but they may well have (and generally will have) differing concentrations in a liquid in equilibrium with the gas. In such a case, if the liquid vanished, the relative gas concentrations would change. Liquids can pack more or less gas moles per volume than the gas above them. Cold water, for example, has about half as much oxygen per liter as the air above it. If the water vanished in an equilibrium mix of air and water, obviously the remaining air would have to accomodate a volume of gas with a lower oxygen volumetric content than air, and thus O2 partial pressure for the new mix would drop. I'll fix this in the text. SBHarris 22:45, 23 November 2006 (UTC)

[edit] Very good article. Helped me a lot.

In my opinion it is a very good article it helped me a ton with my science fair project and it is very useful in learning about lung capacity. —Preceding unsigned comment added by 66.119.143.249 (talk • contribs) December 7, 2006

[edit] Disagree with the proposed merger

I thoroughly disagree with the proposed merger. There may be some redundancy between the two articles, but that is true of a great many Wikipedia articles. I see no great benefit or reason for this specific proposed merger. - mbeychok 19:22, 12 March 2007 (UTC)

I also disagree. This law belongs here. It can be copied, but not moved elsewhere. Xyzt1234 14:37, 26 April 2007 (UTC)

It is not necessary .. the link to the partial pressure is working enough. —Preceding unsigned comment added by 58.181.106.119 (talk • contribs) 18 June 2007 (UTC)

[edit] Removing proposed merger tag

The proposed merger tag was placed on Feb.22, 2007. After 4 months, there have been 3 comments disagreeing with the proposed merger and none that agree with it. I am therefore removing the tag. - mbeychok 18:45, 18 June 2007 (UTC)