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We need to merge this with the page Thermodynamics equations (with an "s"). I think the title "Thermodynamic equations" (without the "s") is a more correct name, so if nobody objects, we could move the material from the "s" page to this page. I started by moving the introduction.
Paul Reiser 04:56, 16 Mar 2005 (UTC)
I added "and reversible" to the the section about adiabatic processes. If we distinguish between the two, the formula is only correct for reversible processes (no raise of entropy due to irreversibility). ThorinMuglindir 22:02, 29 October 2005 (UTC)
While it is a very good start, this page needs adressing the issue of applicability of these equations. Basically all this leaves apart all cases where pressure is not the only source of work. There are some instances where they could encourage some classic mistakes of physics student. For example, if someone tried to solve a problem involving a red-ox battery using the formula for the differential of free energy. I will adress this in the coming weeks. Basically a question: is this article intended to remain as much of a pure formular as can be? Text can be kept as low as possible, but IMO a few explanations wouldn't hurt. Leaving no text at all is not possible as these equations have precise application condions. ThorinMuglindir 23:44, 29 October 2005 (UTC)
In this article, it seems like v and V are being used interchangeably to represent volume. Is this correct, or do they mean different things? If not, it needs to be made consistent to avoid confusion. If so, then the meaning of the two need to be clarified. (BTW, I also agree that the articles should be merged, and in the process, the other article can be cleaned up and sorted.) MagiMaster 17:19, 9 July 2006 (UTC)
This article designates the Helmholtz Free Energy in most places as F, but A is more conventional these days. There are also places at the end where it is listed as A. I think it would be reasonable to go through and change all instances of the variable to A, which is the variable used on the Helmholtz free energy page and is in any case preferred by IUPAC. -- Pmetzger 23:24, 27 September 2006 (UTC)
I'm not a master of equations or anything, but I am confused in the Isothermal equation for the amount of work done by a gas as to whether the negative sign in front of nRTln(V2/V1) is supposed to be there. Under the article of Isothermal Processes, the negative sign is not present, so something must be done to make sure these two equations are consistent.
I have replaced the page with a new page. It gives some structure to what was a disorganized mass of thermodynamic equations and refers the reader to other articles for more detail. Most of what was in the old page is in the new page, but in a more ordered manner. Some equations have been removed since they were just examples of equations that can be found in the links to the more detailed articles. Other equations have been removed because their terms were not defined. The ideal gas table has been moved to the ideal gas page. PAR 22:44, 16 December 2006 (UTC)
I am really, really unhappy with this complete rewrite. Over a long period of time, people contributed a reference page for important thermodynamic equations, much like the table of integrals page and the table of derivatives page. I used this page myself all the time to look up important relations. PAR has butchered this. I'm really unhappy with the changes and intend to revert them unless there is some major objection. Why? Because PAR has effectively removed most of the old content of the page, and replaced it with, dare I say it, incomprehensible prose. -- Pmetzger 23:55, 18 December 2006 (UTC)
Comment (edit conflict) "...vandalism" might be too strong a word here. there seems to be no reason not to assume good faith on PAR's part. both versions are not so bad that they are unreadable. the issue central to the dispute seems to be the intended audience and purpose of the article. the the version before the rewrite, version 1, can be read by anybody with backgound in statisical mechanics. the rewritten version, version 2, has accompanying texts for explanatory purposes.
as was pointed out above, version 1 was serving much like an integral table (hell, i didn't even know WP had those). while almost every elementary calculus text has integral and derivative tables, same seems to not be true for introductory stat mech texts and thermodynamic equations. one can certainly argue, as Pmetzger has, an article listing all common equations one could find, has a place in WP. the accompanying text could be minimal.
on the other hand, if the article is to list the main thermodynamic equations and explain, to some extent, how they are related in the overall scheme, version 2 doesn't do all that shabby in my opinion. such an article necessarily requires some additional text, and its utility as an equation table would be probably reduced. not easy to try to shed light on something while giving all possible information at the same time.
by the way, Pmetzger is probably right in that version 1 contains substantially more equations than version 2. for example, the entire table regarding the ideal gas is absent in version 2. but that's beside the point, seems to me the intended purpose of article needs to be resolved. Mct mht 03:24, 19 December 2006 (UTC)
Hi, generally the idea in WP is to add text to lists, not the other way around as Pmetzer is suggesting. I do, however, see User:Loodog's point that what he wants is an "equation cheat-sheet" to use on tests or whatever; possibly something like the List of laws of science. The present article is a good contrib by User:PAR, I'm presently doing a little cleaning and smoothing to it. Next, to solve the conflict, we could paste the old version into List of thermodynamic equations, and just strip it of text for those who want this kind of stuff. Comment if you like this solution. -- Sadi Carnot 03:34, 19 December 2006 (UTC)
I would probably intersperse some text into this section: Bridgman's thermodynamic equations#Bridgman's thermodynamic equations, to make it more readable as to what these equations are used for. -- Sadi Carnot 05:04, 19 December 2006 (UTC)
I very much prefer the rewritten version. In fact we are having too many equation cheat-sheets and hey ma, I can proof this theorem pages ( Tsirelson's bound anybody?). They are out of scope for an encyclopedia.
But don't worry, they are excellent ideas for a treatment at b:, gaps the size of galaxy superclusters wait to be filled there! With unified login coming Real Soon Now, another excuse for not writing at b: goes down the drain.
Pjacobi 08:45, 19 December 2006 (UTC)
People have a strange idea here of what an encyclopedia is. It functions both as an educational work and as a reference work. I pick up my CRC Handbook and I find tables just like this. The function of an encyclopedia is partially to provide people with information at their fingertips. If you guys are right, why are people so fond of the other tables Wikipedia maintains? Why do we have tables of integrals, for example? There was no reason for this article other than to provide such a table -- the information in the rewrite was around in other articles already.
Let me also say that the rewrite, in and of itself, is awful. It is putatively there to provide information, but it does not. It is written in a style that is opaque even to someone quite familiar to the topic, namely me. I find that the syntax is complicated, the choice of terms is opaque, and the meaning is often so obscure that I cannot tell if PAR is correct or not. This is a serious problem.
If consensus really is to leave the rewrite alone, I'll simply take the content of the old page and create a Table of thermodynamic equations page. I, at least, found the old page a valuable reference work and I don't want to lose it. -- Pmetzger 14:00, 19 December 2006 (UTC)
So it appears that the current feeling is that the new article is good but that the old article did indeed serve a valid purpose. (I apologize to PAR if my reaction was overly heated -- I'm somewhat miffed that he so thoroughly changed the purpose of the original page without discussing it first, but it appears more people seem to agree with him than not.) I'll therefore be copying the old content to Table of thermodynamic equations some time soon, and leaving a link in the edit history to the Thermodynamic Equations page so that people can see the old history. I'll also move some portion of the Talk page from the old version over to the new page as soon as that seems reasonable. I'll also go to the pages linking to Thermodynamic Equations and add links to Table of thermodynamic equations where appropriate. -- Pmetzger 16:35, 19 December 2006 (UTC)
Comment: neither table of derivatives not table of thermodynamic equations are “tables”; it’s like calling a circle a square. But, it’s not a point I am going to bother to argue about. Later: -- Sadi Carnot 22:00, 20 December 2006 (UTC)
Comment: I'll take blame for creating the "so-called" table in the first place, (maybe more than 5 years ago). Technically, yes, table of thermodynamic equations is a table, as in the whole wiki-article is in tabular form. Encyclopedias contain information in various formats: tables, graphs, timelines, etc. While (or if) wiki-articles are not in "journal" style, they are still none-the-less encyclopedic. So, from the discussion above the the conflict is resolved and both articles exist and maintain their uniqueness. Right? Hard Raspy Sci 04:38, 3 January 2007 (UTC)
Pressure is SMALL p, i'm sick of seeing this big P plastered all over wikipedia, hehe!!
... not sure this is meaningful or useful. It also mentions millions of equations, which again looks wrong to me. 82.69.54.182 ( talk) 18:20, 5 August 2008 (UTC)
'The intensive variables may be viewed as a generalized "force". An imbalance in the intensive variable will cause a "flow" of the extensive variable in a direction to counter the imbalance.'
Perhaps 'escaping tendency' would be better? I really hate 'force' of any kind in thermodynamics, though it is related to dynamics. 'Escaping tendency' is at least a scalar quantity.
Also, try the above paragraph out on the Gibbs-Duhem equation, or any heterogeneous mixture with two phases built of the same components, but having different compositions. It can confuse beginning students, for using the paragraph needs careful treatment by experienced hands.
There is also a good argument for using 'dual' rather than 'conjugate', but no one would accept that. Geologist ( talk) 11:43, 7 January 2012 (UTC) :-)
I gather that the differential notation used in the "first law" section is common in physics and/or thermodynamics. However, I don't think it has explicit meaning in mathematics. As a non (physics) specialist I would prefer to see Leibnitz notation or other notation that tells us what the differential is with respect to. Are the differentials on the right in any particular direction? Is the differential of P to be considered with T held constant? Is the differential of G with respect to P and/or V? The accompanying verbage does not make this any clearer.
I've seen elsewhere (link below) where the meaning was given by an associated and more explicit integral equation. Alternatively I think the notation should be explained or a citation should be provided to an explicit definition.
http://en.wikipedia.org/wiki/Stochastic_differential_equation#Note_on_.22the_Langevin_equation.22
Pondhockey ( talk) 21:54, 24 January 2012 (UTC)
Thank you for the reply, and apologies for the very long delay. The differential that you write above is fine in mathematics, and has explicit meaning as a real valued function of the two real valued differentials dx and dy. They are specifically NOT the leibnitz variables of integration, so can you tell me what it means that df "takes on explicit meaning upon integration"? Pondhockey ( talk) 20:02, 8 June 2015 (UTC)
I see that U=TS+pV+...follows Euler's homogeneous function theorem for constant T,P,..., but what connects different temperatures or pressures? Chris2crawford ( talk) 15:43, 19 February 2017 (UTC)
![]() | This ![]() It is of interest to the following WikiProjects: | ||||||||||||||||||||
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We need to merge this with the page Thermodynamics equations (with an "s"). I think the title "Thermodynamic equations" (without the "s") is a more correct name, so if nobody objects, we could move the material from the "s" page to this page. I started by moving the introduction.
Paul Reiser 04:56, 16 Mar 2005 (UTC)
I added "and reversible" to the the section about adiabatic processes. If we distinguish between the two, the formula is only correct for reversible processes (no raise of entropy due to irreversibility). ThorinMuglindir 22:02, 29 October 2005 (UTC)
While it is a very good start, this page needs adressing the issue of applicability of these equations. Basically all this leaves apart all cases where pressure is not the only source of work. There are some instances where they could encourage some classic mistakes of physics student. For example, if someone tried to solve a problem involving a red-ox battery using the formula for the differential of free energy. I will adress this in the coming weeks. Basically a question: is this article intended to remain as much of a pure formular as can be? Text can be kept as low as possible, but IMO a few explanations wouldn't hurt. Leaving no text at all is not possible as these equations have precise application condions. ThorinMuglindir 23:44, 29 October 2005 (UTC)
In this article, it seems like v and V are being used interchangeably to represent volume. Is this correct, or do they mean different things? If not, it needs to be made consistent to avoid confusion. If so, then the meaning of the two need to be clarified. (BTW, I also agree that the articles should be merged, and in the process, the other article can be cleaned up and sorted.) MagiMaster 17:19, 9 July 2006 (UTC)
This article designates the Helmholtz Free Energy in most places as F, but A is more conventional these days. There are also places at the end where it is listed as A. I think it would be reasonable to go through and change all instances of the variable to A, which is the variable used on the Helmholtz free energy page and is in any case preferred by IUPAC. -- Pmetzger 23:24, 27 September 2006 (UTC)
I'm not a master of equations or anything, but I am confused in the Isothermal equation for the amount of work done by a gas as to whether the negative sign in front of nRTln(V2/V1) is supposed to be there. Under the article of Isothermal Processes, the negative sign is not present, so something must be done to make sure these two equations are consistent.
I have replaced the page with a new page. It gives some structure to what was a disorganized mass of thermodynamic equations and refers the reader to other articles for more detail. Most of what was in the old page is in the new page, but in a more ordered manner. Some equations have been removed since they were just examples of equations that can be found in the links to the more detailed articles. Other equations have been removed because their terms were not defined. The ideal gas table has been moved to the ideal gas page. PAR 22:44, 16 December 2006 (UTC)
I am really, really unhappy with this complete rewrite. Over a long period of time, people contributed a reference page for important thermodynamic equations, much like the table of integrals page and the table of derivatives page. I used this page myself all the time to look up important relations. PAR has butchered this. I'm really unhappy with the changes and intend to revert them unless there is some major objection. Why? Because PAR has effectively removed most of the old content of the page, and replaced it with, dare I say it, incomprehensible prose. -- Pmetzger 23:55, 18 December 2006 (UTC)
Comment (edit conflict) "...vandalism" might be too strong a word here. there seems to be no reason not to assume good faith on PAR's part. both versions are not so bad that they are unreadable. the issue central to the dispute seems to be the intended audience and purpose of the article. the the version before the rewrite, version 1, can be read by anybody with backgound in statisical mechanics. the rewritten version, version 2, has accompanying texts for explanatory purposes.
as was pointed out above, version 1 was serving much like an integral table (hell, i didn't even know WP had those). while almost every elementary calculus text has integral and derivative tables, same seems to not be true for introductory stat mech texts and thermodynamic equations. one can certainly argue, as Pmetzger has, an article listing all common equations one could find, has a place in WP. the accompanying text could be minimal.
on the other hand, if the article is to list the main thermodynamic equations and explain, to some extent, how they are related in the overall scheme, version 2 doesn't do all that shabby in my opinion. such an article necessarily requires some additional text, and its utility as an equation table would be probably reduced. not easy to try to shed light on something while giving all possible information at the same time.
by the way, Pmetzger is probably right in that version 1 contains substantially more equations than version 2. for example, the entire table regarding the ideal gas is absent in version 2. but that's beside the point, seems to me the intended purpose of article needs to be resolved. Mct mht 03:24, 19 December 2006 (UTC)
Hi, generally the idea in WP is to add text to lists, not the other way around as Pmetzer is suggesting. I do, however, see User:Loodog's point that what he wants is an "equation cheat-sheet" to use on tests or whatever; possibly something like the List of laws of science. The present article is a good contrib by User:PAR, I'm presently doing a little cleaning and smoothing to it. Next, to solve the conflict, we could paste the old version into List of thermodynamic equations, and just strip it of text for those who want this kind of stuff. Comment if you like this solution. -- Sadi Carnot 03:34, 19 December 2006 (UTC)
I would probably intersperse some text into this section: Bridgman's thermodynamic equations#Bridgman's thermodynamic equations, to make it more readable as to what these equations are used for. -- Sadi Carnot 05:04, 19 December 2006 (UTC)
I very much prefer the rewritten version. In fact we are having too many equation cheat-sheets and hey ma, I can proof this theorem pages ( Tsirelson's bound anybody?). They are out of scope for an encyclopedia.
But don't worry, they are excellent ideas for a treatment at b:, gaps the size of galaxy superclusters wait to be filled there! With unified login coming Real Soon Now, another excuse for not writing at b: goes down the drain.
Pjacobi 08:45, 19 December 2006 (UTC)
People have a strange idea here of what an encyclopedia is. It functions both as an educational work and as a reference work. I pick up my CRC Handbook and I find tables just like this. The function of an encyclopedia is partially to provide people with information at their fingertips. If you guys are right, why are people so fond of the other tables Wikipedia maintains? Why do we have tables of integrals, for example? There was no reason for this article other than to provide such a table -- the information in the rewrite was around in other articles already.
Let me also say that the rewrite, in and of itself, is awful. It is putatively there to provide information, but it does not. It is written in a style that is opaque even to someone quite familiar to the topic, namely me. I find that the syntax is complicated, the choice of terms is opaque, and the meaning is often so obscure that I cannot tell if PAR is correct or not. This is a serious problem.
If consensus really is to leave the rewrite alone, I'll simply take the content of the old page and create a Table of thermodynamic equations page. I, at least, found the old page a valuable reference work and I don't want to lose it. -- Pmetzger 14:00, 19 December 2006 (UTC)
So it appears that the current feeling is that the new article is good but that the old article did indeed serve a valid purpose. (I apologize to PAR if my reaction was overly heated -- I'm somewhat miffed that he so thoroughly changed the purpose of the original page without discussing it first, but it appears more people seem to agree with him than not.) I'll therefore be copying the old content to Table of thermodynamic equations some time soon, and leaving a link in the edit history to the Thermodynamic Equations page so that people can see the old history. I'll also move some portion of the Talk page from the old version over to the new page as soon as that seems reasonable. I'll also go to the pages linking to Thermodynamic Equations and add links to Table of thermodynamic equations where appropriate. -- Pmetzger 16:35, 19 December 2006 (UTC)
Comment: neither table of derivatives not table of thermodynamic equations are “tables”; it’s like calling a circle a square. But, it’s not a point I am going to bother to argue about. Later: -- Sadi Carnot 22:00, 20 December 2006 (UTC)
Comment: I'll take blame for creating the "so-called" table in the first place, (maybe more than 5 years ago). Technically, yes, table of thermodynamic equations is a table, as in the whole wiki-article is in tabular form. Encyclopedias contain information in various formats: tables, graphs, timelines, etc. While (or if) wiki-articles are not in "journal" style, they are still none-the-less encyclopedic. So, from the discussion above the the conflict is resolved and both articles exist and maintain their uniqueness. Right? Hard Raspy Sci 04:38, 3 January 2007 (UTC)
Pressure is SMALL p, i'm sick of seeing this big P plastered all over wikipedia, hehe!!
... not sure this is meaningful or useful. It also mentions millions of equations, which again looks wrong to me. 82.69.54.182 ( talk) 18:20, 5 August 2008 (UTC)
'The intensive variables may be viewed as a generalized "force". An imbalance in the intensive variable will cause a "flow" of the extensive variable in a direction to counter the imbalance.'
Perhaps 'escaping tendency' would be better? I really hate 'force' of any kind in thermodynamics, though it is related to dynamics. 'Escaping tendency' is at least a scalar quantity.
Also, try the above paragraph out on the Gibbs-Duhem equation, or any heterogeneous mixture with two phases built of the same components, but having different compositions. It can confuse beginning students, for using the paragraph needs careful treatment by experienced hands.
There is also a good argument for using 'dual' rather than 'conjugate', but no one would accept that. Geologist ( talk) 11:43, 7 January 2012 (UTC) :-)
I gather that the differential notation used in the "first law" section is common in physics and/or thermodynamics. However, I don't think it has explicit meaning in mathematics. As a non (physics) specialist I would prefer to see Leibnitz notation or other notation that tells us what the differential is with respect to. Are the differentials on the right in any particular direction? Is the differential of P to be considered with T held constant? Is the differential of G with respect to P and/or V? The accompanying verbage does not make this any clearer.
I've seen elsewhere (link below) where the meaning was given by an associated and more explicit integral equation. Alternatively I think the notation should be explained or a citation should be provided to an explicit definition.
http://en.wikipedia.org/wiki/Stochastic_differential_equation#Note_on_.22the_Langevin_equation.22
Pondhockey ( talk) 21:54, 24 January 2012 (UTC)
Thank you for the reply, and apologies for the very long delay. The differential that you write above is fine in mathematics, and has explicit meaning as a real valued function of the two real valued differentials dx and dy. They are specifically NOT the leibnitz variables of integration, so can you tell me what it means that df "takes on explicit meaning upon integration"? Pondhockey ( talk) 20:02, 8 June 2015 (UTC)
I see that U=TS+pV+...follows Euler's homogeneous function theorem for constant T,P,..., but what connects different temperatures or pressures? Chris2crawford ( talk) 15:43, 19 February 2017 (UTC)