Talk:Compressibility factor

Discussion Section
I added a discussion of significance and removed what I thought was a redundancy in introduction. I think any kind of graphic could really improve this page. I did a compressibility determination for CO2 lab a while back; I could include some of the graphs I generated there. 14 June (talk) 20:01, 29 February 2008 (UTC)

Including a compressibility chart
I think this article could benifit greatly from an actual compressibility chart, and the only good one i have encountered is the Nelson-Obert generalized compressibility chart, which is stated as being 'used with permission of Dr. Edward E. Obert, University of Wisconsin'. If someone can find a good chart, please upload it, or maybe somebody can track down Dr. Obert and ask him to release it as he does not appear in the persons search on the universities website and mail to edwardobert@wisc.edu fails to send. powerfool 15:45, 20 November 2006 (UTC)


 * I have moved the compressibility chart article here to compressibility factor. The following "discussion" is from the talk page of compressibility chart. I am including it here for reference and further discussion. -Myth (Talk) 05:02, 22 February 2007 (UTC)


 * There is an excellent online compressibility chart Here. If someone could contact Dr. Igor Voronkov of the Physics Dept. at the University of Alberta (Canada) and at this email address at igor@space.ualberta.ca ... he might be helpful in getting a GFDL License to use the chart in Wikipedia. - mbeychok 06:14, 18 July 2007 (UTC)

General trend of compressibility
"The value of Z generally increases with pressure and decreases with temperature." This statement is too vague. Does Z increase with increasing pressure or decreasing pressure; and the same for temperature. the statement would seem to imply that Z increases with changing pressure regardless of wether or not the pressure is getting bigger or smaller; and the same for temperature. Specifically say if it is increasing or decreasing pressure, and increasing or decreasing temperature. Although it may be obvious from the equations for the compressibilty i feel it should still say so.128.111.34.165 (talk) 19:48, 6 May 2009 (UTC)

Based on the formula, Z would increase with higher pressure and temperature. Z would then decrease with low pressure, high temperature, showing deviations from the ideal. However, doesn't a higher pressure and lower temperature (increased Z) lead to Z > 1? That seems counter-intuitive to me. MinkeyBuddy (talk) 15:16, 29 May 2009 (UTC)

Quantum gas formulae dimension error
Dimensions in quantum gas formulae are inconsistent. In T_r=T/(T_c+8) T_c is carrying dimensions while 8 is just a number (no dimensions). Likely to mean 8K. The same stands in P_r=P/(P_c+8), where here there is no way to assess the unit of pressure referred to that 8.

Consider "T_r=T/(T_c+b) where b=8K" and pretty much the same for the equation on P.

Etaoin Shdrlu (talk) 08:43, 26 October 2009 (UTC)


 * I also would like to know what the units are of the mysterious 8 in each of the two equations. I dug back through the history of the page and found that these were added at this point:


 * http://en.wikipedia.org/w/index.php?title=Compressibility_factor&oldid=237011358
 * at 05:25, 8 September 2008 by‎ Rikki1989.


 * However, it seems that username Rikki1989 no longer exists. I was hoping to request the source  of that information.


 * Kimaaron (talk) 04:08, 7 April 2012 (UTC)


 * I found the equations in question at this location:
 * http://en.citizendium.org/wiki/Compressibility_factor_%28gases%29#cite_ref-Rao_3-0
 * and there they state that the units are Kelvin and atmosphere, so I added a line to our main page indicating that.
 * Note, this is the first external reference on our page.
 * I also added a reference cited at that same location.


 * Kimaaron (talk) 05:52, 26 April 2012 (UTC)

Link to the potential of intermolecular forces

 * It seems that there are inconsistencies between various sources/textbooks regarding the presence/absence of some coefficients like Avogadro's number in the equation connecting the compressibility factor to the potential of intermolecular forces:


 * $$Z= 1 + 2 \pi \frac {N_A}{V_M} \int_{0}^\infty (1 - exp ({\frac{\varphi}{kT})) r^2 dr}$$

I think it should be clarified.--188.26.22.131 (talk) 12:19, 8 December 2014 (UTC)

New section on physical reasons for behavior
I have inserted a new section giving the physical reasons why the compressibility factor varies as it does. I think this at least partially addresses the first two comments above. Also this section is linked to in the article on the Joule-Thomson coefficient (sort of, there is a silly issue with the link). Retired Pchem Prof (talk) 04:24, 19 January 2016 (UTC)

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is there a reason the Generalized compressibility factor diagram is in italian?
is there an english version? — Preceding unsigned comment added by 81.109.61.206 (talk) 15:35, 7 March 2021 (UTC)