Talk:Phase diagram

message: Don't chemists use the term phase diagram for the P-T diagrams showing the lines of equilibium (and the triple point) between eg solid, liquid and gas phases of a pure substance?
Linuxlad 22:54, 18 Feb 2005 (UTC)
replies: text: I now have permission from Pearson to include this. Linuxlad 22:00, 23 May 2005 (UTC)

message: When people talk about phase diagrams they usually mean Pressure on the ordinate, T on the abscissa, for one particular material.  When talking about binary phase diagrams, two different materials (usually pure metals) are mixed on a continuum in the abscissa, with T on the ordinate.  Currently Binary phase diagram links to this page, when it actually needs its own.
Riceplaytexas 07:09, 13 January 2007 (UTC)
replies: text: I disagree with you on this point. In my experience, people use "Phase diagram" about both P-T diagrams, binary and ternary phase diagrams. This is just my personal experience though, it may be that it is different from field to field, university to university, or country to country. Dr bab 07:51, 25 April 2007 (UTC)
thread_title:  Phase Diagram ≠ Binary Phase Diagram 

message: In the table of transitions plasma is reached only from gas/fluid. But this is not so obvious from the P-T diagram - there it seems that if P is high enough maybe solid-to-plasma transition can occur. It is not very clear, because plasma is not shown on the P-T diagram. So, we should either mention solid-to-plasma or change the P-T diagram so that it shows a negative slope on the solid/liquid line after some point so that there is no solid-to-plasma. In either case the plasma phase should be added to the P-T diagram. Alinor (talk) 17:50, 4 October 2009 (UTC)
thread_title:  solid to plasma transition 

message: There is a problem with the first diagram for one component in two dimensions. The regions labelled "superheated vapour" and "gaseous phase" should be interchanged. A vapour is defined as a gas which is below its critical temperature, so the region T > Tc cannot be described as a vapour and should simply be labelled "gas". The low-T region can be described as "vapour", though "vapour (gas)" would probably be better, since the vapour phase is physically a gas. 
As for the word "superheated", this term is used mostly for steam (water), for which superheated steam is steam above the normal boiling point. This is not really a useful term to explain phase diagrams and should be omitted.
This problem was noted on 27 January 2010 in the Gibbs' phase rule article which uses the same diagram. As far as I can figure out, the diagram was originally drawn by an editor who is now inactive. Can someone please redraw the diagram and label it correctly?  Dirac66 (talk) 03:02, 2 February 2010 (UTC)
replies: text: You are talking about :File:Phase-diag2.svg, right? The explanation of the image on it's description page says it's for water, therefore it is currently correct, I think. I'm not sure I completely follow what you are trying to say. If you can accurately explain what is should be I can fix it for you. Wizard191 (talk) 13:58, 2 February 2010 (UTC)
replies: text: Thanks. Yes, you have the right file. The required changes to the diagram are (1) change the label "superheated vapour" to "gas phase" and (2) change the label "gaseous phase" to "vapour". The reason is that vapour is defined as a gas below the critical temperature, not above as in the present diagram.  Dirac66 (talk) 15:10, 5 February 2010 (UTC)
replies: text: Done! Wizard191 (talk) 17:32, 5 February 2010 (UTC)
replies: text: Thank you - the diagram is now more accurately labelled. And a note to others who read this - if like me you don't see the change at first, try renewing the cache (F5 on a PC) where your computer stores the old version. Dirac66 (talk) 20:27, 5 February 2010 (UTC)
thread_title:  Vapour and gas interchanged 

message: To Wizard 191: I think you were too quick to revert the edit by 86.16.21.74 as "vandalism". Yes, this editor deleted a whole diagram without explanation in the edit summary. However the section Crystal phase diagrams now contains two very similar diagrams both showing the phases of high-pressure phases of ice as a function of log P and T, so I think 86.16.21.74 was justified in deleting the less aesthetic version. Please revert your edit and delete this diagram again.Dirac66 (talk) 19:20, 24 May 2011 (UTC)
replies: text: Materialscientist already reverted me. I didn't realize there were two similar images, but the edit looked like vandalism so I reverted it. Sorry about that. Wizard191 (talk) 16:10, 25 May 2011 (UTC)
replies: text: Actually, those deletions almost tripped me to revert too, and I went looking for the duplicates of this diagram and got here. IP edits w/o edit summaries are a nuisance. Materialscientist (talk) 00:49, 26 May 2011 (UTC)
thread_title:  One diagram for high-pressure ice is enough 

message: This diagram currently attributed to Cmglee is derivative of phase diagrams on my website over the years and should reference this website http://www1.lsbu.ac.uk/water/water_phase_diagram.html81.157.18.224 (talk) 12:00, 30 June 2015 (UTC)
replies: text: I think you mean the one in the section Crystal phase diagrams which has crystalline phases up to Ice XI. Cmglee claims to have drawn the actual file which appears in Wikipedia, but not that the schema is entirely original. I would presume that similar diagrams can be found not only on your website, but also in some number of books or articles on the subject. Perhaps the simplest solution would be to add a note saying that "A similar diagram may be found on the site http://www1.lsbu.ac.uk/water/water_phase_diagram.html." Dirac66 (talk) 02:08, 1 July 2015 (UTC)

text: OK, I have made the suggested addition to the figure title, and included the website title. Dirac66 (talk) 21:57, 2 July 2015 (UTC)
thread_title:  The Phase Diagram of water. 

message: There are, imho, lots of problems with this article (specifically in the earlier parts, I didn't read it in its entirety). Firstly, it seems to assume that the phases are of the thermodynamical variables P and T. In reality, as most here know, a phase diagram may indicate a variety of phases including composition or spin or a host of others. Secondly, in  reading the article lede and overview, I'm still not sure what it is that a phase diagram is showing. For instance the text claims that the blue line in the first figure shows the 'boiling point' as a function of pressure. BUT typically the independent variable is on the x-axis (horizontal) so, the line would (to someone not ever having learned better) show the boiling point varying with Temperature. Maybe its "toe may toe" vs "tah mah toe", but isn't clear.  The text CLAIMS that the lines mark the conditions which allow multiple phases to co-exist. This OBVIOUSLY implies that away from the lines, only ONE PHASE will exist. We know this just ain't so.
For a P-T phase diagram, typically TWO phases will coexist (in most (many?) areas of a PT diagram). If I look up STP on the water p.d. I see water exists as vapor, supposedly. That would be real news to fish the world over. I actually came to this article looking to refresh my memory of what the various areas in a PT p.d. represent and man, did I NOT find anything intelligible! So, I'll either have to recreate what I learned about p.d.s in school those many decades ago and 'fix' the article myself, or rely on others to do it. At this point, I'm hoping someone else will jump in, since I'm just not clear enough about what these things are showing to express it in a simple way. They don't show "equilibrium" processes at all, rather they indicate the boundary lines, on ONE SIDE of at which, as either (2° diagram) variable CHANGES, and ONE phase MIGHT disappear. So two major issues: one - the lede and overview fail to inform a casual reader what the typical diagram is showing and the article confuses the reader by implying that only one phase exists at a given P and T. It also seems to confuse a reversible DYNAMIC system with a system at equilibrium.  I also add that in a gravitational field (don't know where those don't exist, do you?) pressure/density can only approximately be uniform for a finite (say, macroscopic) volume. (this is a nit-pick, but should be made explicit somewhere in the article). I also don't at all agree that a Temperature-Entropy diagram (or a Pressure-enthalpy or entropy-enthalpy diagrams) are "PHASE" diagrams. Certainly the HUGE diagram of T-E is inappropriate here.  (eg. ONLY liquid water exists 'to the left of the dome'???). If a diagram doesn't have phases in it, it isn't a phase diagram (the lower 3 diagrams "for steam" apparently are of a SINGLE phase? At the very least they add nothing to the intelligibility of the article, regardless if we have permission to use them. Simply because some diagram has two or more phases (of a material) indicated, DOESN'T make it a "phase diagram". [just like it isn't useful to describe any bus which happens to have a celebrity on board as a celebrity bus.]
First thing that needs doing is a clear, concise, simple, and USEFUL explanation for someone picking an arbitrary point on a diagram, either on or off a phase transition line, that clearly and simply explains how to interpret the p.d. for that point. 216.96.77.80 (talk) 20:20, 7 August 2015 (UTC)
thread_title:  Typical phase diagram 

message: Hello fellow Wikipedians,
I have just modified 2 external links on Phase diagram. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
*Added archive https://web.archive.org/web/20080216023642/http://www.sv.vt.edu/classes/MSE2094_NoteBook/96ClassProj/examples/kimcon.html to http://www.sv.vt.edu/classes/MSE2094_NoteBook/96ClassProj/examples/kimcon.html
*Added archive https://web.archive.org/web/20060427102513/http://www.matter.org.uk/steelmatter/metallurgy/6_1_3_1.html to http://www.matter.org.uk/steelmatter/metallurgy/6_1_3_1.html
When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.
Cheers.—InternetArchiveBot (Report bug) 20:21, 5 December 2017 (UTC)
thread_title:  External links modified 

message: This page could be improved by the addition of a description of how phase diagrams are generated using modern methods and instrumentation.  — Preceding unsigned comment added by 75.80.48.54 (talk) 16:41, 24 June 2021 (UTC)
thread_title:  How are phase diagrams generated? 

message: I had my comment that nitrogen ice floats in its liquid reverted because some reference claimed this happened at very high pressures only. Not true. I pumped on my dewar of LN2 to get my sample below 77K. I watched as small ice particles then large chunks formed floating on the surface. Then the whole surface froze, got thicker and eventually froze the entire dewar solid N2 - from top to bottom. I got down to 54K. I don’t have a reference - just experimental fact. Bscip (talk) 19:25, 25 August 2021 (UTC)
replies: text: I agree that the observations you describe seems to be at much lower pressure than the results of Mukherjee and Boehler in their Physical Review Letter. But to appear in Wikipedia, your observation has to be supported by a published reference so we can be certain it has been observed and interpreted correctly, at least in the opinion of a journal referee. You might try checking the articles on solid nitrogen and liquid nitrogen to see if anyone has reported observations similar to yours. Dirac66 (talk) 01:12, 26 August 2021 (UTC)
thread_title:  Nitrogen ice