Talk:Gibbs free energy/Archive 1

message: In the section that derives Gibb's free energy, an explanation of what Q is, is missing. Perhaps someone who knows exactly what Q is defined as, could edit the page with an explanation.
:Q is heat transfer, and the article says so repeatedly. — Miguel 03:21, 2004 Oct 28 (UTC)
:: Q must be dimensionless for ln(Q) to make sense. I think it is the relative pressure (the ratio between the actual pressure and the atmospheric pressure)
::--HenrikMidtiby 21:06, 16 January 2006 (UTC)
replies: text:  Q, if I remember correctly, is the reaction quotient.  It is similar to the equilibrium constant expression; they are the same after the reaction has gone to completion.  Hope that helps.  Gchriss 18:24, 5 February 2006 (UTC)
replies: text: heat transfer is small "q" --M1ss1ontomars2k4 18:39, 13 May 2006 (UTC)
thread_title:  '04 questions 

message: the identity relating nFE to RTlnK is incorrect (there shouldn't be a minus there)
:You're right. It's been changed. --M1ss1ontomars2k4 18:43, 13 May 2006 (UTC)
thread_title:  identities 

message: The article states "Such processes do not seem to move on a P-V diagram; they do not seem to be dynamic at all."  I take issue with this, because I can name a million isothermal, isobaric processes that definitely move on a P-V diagram.  Consider boiling water at atmospheric pressure and 100 degrees C... it goes from liquid to gas, and therefore the volume changes drastically.  Shall we remove this statement? Ed Sanville 21:54, 10 November 2005 (UTC)
thread_title:  Isothermal, isobaric processes 

message: What does the G equate to in conceptual terms? Is it for instance, the amount of thermal energy contained in a given volume? Could it be expressed as 'the amount of energy that would dissipate if the mass of given material were released to the great vacuum of space', not considering radioactive decay or chemical interactions? -- Pinbucket 00:06, 18 March 2006 (UTC)
replies: text: No, basically, if you do an energy balance on constant-temperature, constant-pressure reacting system, i.e. final "total energy" = initial "total energy", you can facilitatively divide this total energy [H] released from the chemical reaction into two parts: (a) useable part = [G]; (b) un-useable part = [TS].--Sadi Carnot 21:05, 11 April 2006 (UTC)
replies: text: The decrease of the Gibbs free energy equals the maximum non-volume (non-boundary) work a system can perform under isothermal, isobaric conditions. That's not quite the same as the maximum work, which is the decrease in the Helmholtz free energy. As correctly noted above, enthalpy [H] equals [G] plus [TS]. For example, a fuel cell can convert the decreased enthalpy into electrical work, the latter equal to the decrease in [G], with the remainder lost as heat. ----PotomacFever 14:24, 21 June 2006 (UTC)
thread_title:  What is it? 

message: DIV, I happen to be coincidently reading Baierlein’s 2003 Thermal Physics (textbook) and in chapter 10 “The Free Energies”, section 10.4, the topic is Gibbs free energy.  Imaging that!  Maybe they didn’t get that 1988 IUPAC memo?  The point here is that this is an article for the English speaking world, we have to go with the most common term, i.e. the one that is most commonly used in textbooks, lectures, and in the common tongue.  Maybe, in the future, things will change and the majority will start to use IUPAC standards? 
Coincidently, off Amazon this last month I ordered over 30 new thermodynamic books (Sandlers I bought years ago), from virtually every branch of thermodynamics, you name it and I probably ordered it (or have it).  My point is that I am going to reason that I am familiar with what is commonly used.  To clarify this discussion one last time, the chapter “History of Thermodynamic Terminology and Notation”, in the book Drug-Receptor Thermodynamics, we find: 
:“Two conveniently defined functions are those that were originally described by using the word ‘free’ to indicate that under special conditions these were energies that were ‘free’ or available for work.  In modern terms we use Gibbs energy or Gibbs function and Helmholtz energy or Helmholtz function; the descriptive ‘free’ has been banished (Mills et al. 1988), although it unfortunately continues to be used.” [(1)Mills I, Cvitas T, Homann K, et al. (1988). Quantities, Units and Symbols in Physical Chemsitry, IUPAC, Blackwell Scientific Publications, Oxford.; (2)Raffa, R.B. (2001). Drug-Receptor Thermodynamics: Introduction and Application. New York: John Wiley & Sons, Ltd.]
Strange, the descriptive 'free' was banished over 20 years ago?  Maybe the people who started this article in 2003 weren't aware of the banishment?  Now, here are the stats for Google hits:
:for the term “Gibbs free energy”:
:Results 1 - 10 of about 2,310,000 for Gibbs free energy [definition]. (0.19 seconds)
:for the term “Gibbs energy”:
:Results 1 - 10 of about 3,680,000 for Gibbs energy. (0.17 seconds) 
As we see there is a toss-up.  Yet when it is referenced in scientific encyclopedias we find a common standard.  For example, here is the article as found in Eric Weissteins World of Physics:
Gibbs Free Energy.  The same is true for Britannica, here is a  2002 reprint of their section on free energy:
:In thermodynamics, energylike property or state function of a system in thermodynamic equilibrium—it has the dimensions of energy and its value is determined by the state of the system and not by its history—expressed in two forms: the Helmholtz free energy, A, sometimes called work function, and the Gibbs free energy, G, sometimes F. If E is the internal energy of the system, PV the pressure–volume product, and TS the temperature–entropy product, then A = E - TS and G = E + PV - TS. Free energy is an extensive property; i.e., the magnitude depends on the amount of the substance present in a given thermodynamic state.
:The changes in free energy, ΔA or ΔG, are useful in evaluating certain thermodynamic processes. In a reversible process, the work under constant temperature and constant volume is equal to the change in the Helmholtz free energy, ΔA, and the work under constant temperature and constant pressure is equal to the change in the Gibbs free energy, ΔG.
:Changes in free energy can be used to judge whether certain transformations of state can occur spontaneously. Under certain conditions of constant temperature and volume, the transformation of state will occur spontaneously, slowly or rapidly, if the Helmholtz free energy of the final state is smaller than that of the initial state; that is, if the difference ΔA between the final and the initial state is negative. Under conditions of constant temperature and pressure, the transformation of state will occur if the change in the Gibbs free energy, ΔG, is negative.
We can go on and on but the fact remains that when people write up the entry in the encyclopedias (as the above two) exacting clarification is used along with a tendency to use the most informative and common term.  In wikipedia, we have 120+ links to the Gibbs free energy page and 0 links to the Gibbs energy page.  I would assume the 120 people who made these links didn’t get the 1988 IUPAC memo either? It is one thing for small committee of chemists to supposedly "ban" a term, and quite another for the world to want the term banned.  As we see, we are in the middle of a 100+ year terminology evolution or transformation window, since the concept was developed by Gibbs in 1876.  In time, maybe another 100 years, we will naturally (hopefully) gravitate towards a final agreement.  To solidify my point, I have added 7 external links to the article (as shown below) --Sadi Carnot 02:56, 20 June 2006 (UTC)
thread_title:  Second conversation 

message: A Request for comment has been made concerning the title of this article here, cross-posted to WikiProject Chemistry and WikiProject Physics. Physchim62 (talk) 23:58, 28 December 2006 (UTC)
thread_title:  RFC 

message: I support keeping 'Gibbs free energy' as the name of the article rather than 'Gibbs energy'. The comments given above seem to be very thorough on both sides of the argument. I note that the large section  provides ample ventilation of the naming issue. The only thing that might potentially be added are references to published debates in scientific journals about which term is better.  EdJohnston 18:40, 28 December 2006 (UTC)
replies: text: The question of naming always raises more dust than light. My own view is that Gibbs energy should be used, following IUPAC unless clear authoritive sources from a standards organisation that covers disciplines other than chemistry that uses the term Gibbs free energy can be cited. I do not think historical useage is in any way important in deciding the name of the article, although it should be mentioned in the article. I agree with Itub that if free energy remains as the title, the IUPAC name should be in the first paragraph. Whatever is decided, the other should be a redirect. There should not be a discussion of the name in the article itself. --Bduke 20:57, 28 December 2006 (UTC)
thread_title: Yet another view on the article name

message: Someone is requesting outside comments on this debate, and here's mine.  Many concepts are known by more than one name. You're never going to settle which name is best. The first sentence of the article can mention the 2 or 3 most common names, and futher discussion of various names, abstracted from your lengthy debate, can be written up as a section. I didn't read too much of your debate, but it seems like there is some concern over breaking links.  The is very simple to deal with using redirects (although eventually these should be cleaned up). My bottom line opinion is that if you can agree on 2 or 3 versions of the name to stick in the first sentence, who cares what the real name of the article is? ike9898 22:27, 1 January 2007 (UTC)
replies: text: It seems to me that that IUPAC tells chemists what to call it, but there is far from any consensus in other disciplines. I suggest that the most likely compromise is to call the article "Gibbs free energy", have a redirect from "Gibbs energy", and mention the latter as the IUPAC recommendation in the lead of the article. Can everyone live with this? --Bduke 23:18, 1 January 2007 (UTC)
replies: text: Yes, I agree with this. --Sadi Carnot 00:25, 2 January 2007 (UTC)
replies: text: I could live with that too. Itub 14:55, 2 January 2007 (UTC)

text: Having quickly read through the comments here, this seems sensible to me. I care less about page titles than that readers get something useful when they search. Tom Harrison Talk 21:43, 2 January 2007 (UTC)
replies: text: Thanks for everyone's opinion, I have changed the intros of both Gibbs free energy and Helmholtz free energy to reflect this view (the redirects already exist). --Sadi Carnot 22:23, 2 January 2007 (UTC)

text: I'd still like to see what the corresponding advice was on the physics side: Cohen, E. R.; Giacomo, P. (1987). "Symbols, Units, Nomenclature and Fundamental Constants in Physics (1987 Revision), Document IUPAP-25 (IUPAP–SUNAMCO 87–1)". Physica A 146: 1–68, as mentioned by User:Physchim62 in the section above. This work is safely locked behind pay walls, so someone will have to go to the library to consult it. If they agree with the chemists, I'd be more inclined to switch to the name 'Gibbs energy'. EdJohnston 23:26, 1 January 2007 (UTC)
replies: text: As to physics consensus, I have copies of Schroeder's 2000 Thermal Physics, Baierlein's 2003 Thermal Physics, and Chang Lee's 2004 Thermal Physics - Entropy and Free Energies, and they all use Gibbs free energy and Helmholtz free energy.  Not only that they also discuss the Landau free energy, the Landau-Ginnzburg free energy, the minimum free energy principle, the Grand free energy, thermodynamic free energy, and others. --Sadi Carnot 00:25, 2 January 2007 (UTC)

text: The recommendation published in Physica A, 146, p. 31 is "Gibbs function" (and "Helmholtz function"). It also includes names in French: "fonction de Gibbs" and "enthalpie libre" (but there is no "free enthalpy" in English); and for Helmholtz, "fonction de Helmholtz" and "énergie libre" (but again, no "free energy" in English). Itub 14:55, 2 January 2007 (UTC)
thread_title: Outsider comment on name discussion

message: Has anyone, other than myself, noticed that DIV is going around Wikipedia and removing all the incidences of the term "free", so far to about 30 articles, with no avail (see: DIV's contributions ), even though there is no consensus and the issue is far from agreed upon? --Sadi Carnot 00:46, 2 January 2007 (UTC)
replies: text: Thanks to User:Physchim62 for fixing this problem! --Sadi Carnot 22:24, 2 January 2007 (UTC)
thread_title: DIV's contributions

message: I'd like to ask a question, or so, here.  First, is the relationship of Gibbs' free energy to life processes seems self evident. (Yes?)  Next, life forms are highly ordered (low entropy) aggregations of matter.  Their formation, therefore, I presume, occurs as another process 'externalises' these, localised, reversals of entopy increase, and of Free Energy decrease. (Is that so?)  Also, have, for example, any measurements of photosynthesis, animal metabolism, etc?, ever been quantified to demontrate the fidelity of these life processes to the Gibbs'(etc) thermodynamic equations. (yes or no?) One final point, I've pondered whether the (human) 'wealth creation' processes could be described by the following word equation:
    Raw Materials + Energy --> Wealth + Pollution
Any comments on this proposition? Thanks! John Courtneidge (presently in Toronto, Canada)
:Yes, many people have stabbed in this direction.  The first was Herbert Spencer in his 1880 book First Principles, but he only speaks in terms ‘available energy’ and resources, dissipation, evolution, etc., not necessarily free energy as it is in the article.  In 1922, Frederick Soddy applied steam engine theory to human life; he states: “life derives the whole of its physical energy or power not from anything self-contained in living matter, but solely from the inanimate world.  It is dependent for all necessities of its physical continuance upon the principles of the steam engine.  The principles of ethics of all human conventions must not run counter to those thermodynamics.”  In 1926, in his book The Biosphere, Vladimir Vernadsky states: “Living matter, as a whole, is a unique system which accumulates chemical free energy G in the biosphere by the transformation of solar radiation.” 
:You might also want to check out Erwin Schrodingers 1944 book What is Life?, his book is the most referenced book in regards to free energy, entropy, negentropy, solar energy input, and evolution.  Another good one is the 1998 book Thermodynamic Theory of the Evolution of Living Beings by Russian physical chemist Georgi Gladyshev.  Also, on the back cover of the 2003 book Information Theory and Evolution by theoretical physicist and chemist John Avery we are told that the paradox between the complexity produced by living systems and the seeming contraction between the second law of thermodynamics has its resolution in the Gibbs free energy that enters the biosphere from outside sources.  This is just quick list. I hope this helps.  Adios:--Sadi Carnot 06:29, 9 July 2006 (UTC)
replies: text:  OK, it being nearly six months on, I'm going to try to do this - I hope many will weigh in with improvements. Best, john John courtneidge 16:55, 23 December 2006 (UTC)
replies: text: Hi John, first I commented to your query on your "new" talk page.  Second, your present contribution is a good topic, however, it will no doubt get reverted by another user fairly soon for a number of reasons, namely we can’t use unsubstantiated theories (every sentence has to be established knowledge); so I will move it here; so we can discuss your contribution, references, and ideas further on that talk page. Thanks: --Sadi Carnot 20:48, 23 December 2006 (UTC)
thread_title:  Gibbs Free Energy, Life Processes and 'Wealth' creation 

message: Lochnagar, 
Good question.  Gibbs free energy is my favorite topic.  As to being able to conceptually understand what Gibbs free energy is; essentially, it is a more advanced and accurate replacement for the term “affinity” used by chemists, of olden days, to describe the “force” that caused chemical reactions.  The term dates back to at least the time of Albertus Magnus in 1250.
From the 1998 textbook Modern Thermodynamics by Nobelist and chemical engineering professor Ilya Prigogine’s we find: “as motion was explained by the Newtonian concept of force, chemists wanted a similar concept of ‘driving force’ for chemical change?  Why do chemical reactions occur, and why do they stop at certain points?  Chemists called the ‘force’ that caused chemical reactions affinity, but it lacked a clear definition. 
During the entire 18th century, the dominate view in regards to heat and light was that put forward by Isaac Newton, called the “Newtonian hypothesis”, which stated that light and heat are forms of matter attracted or repelled by other forms of matter, with forces analogous to gravitation or to chemical affinity.
In the 19th century, the French chemist Marcellin Berthelot and the Danish chemist Julius Thomsen had attempted to quantify affinity using heats of reaction.  In 1875, after quantifying the heats of reaction for a large number of compounds, Berthelot proposed the “principle of maximum work” in which all chemical changes occurring without intervention of outside energy tend toward the production of bodies or of a system of bodies which liberate heat.
In addition to this, in 1780 Antoine Lavoisier and Pierre-Simon Laplace laid the foundations of thermochemistry by showing that the heat evolved in a reaction is equal to the heat absorbed in the reverse reaction.  They also investigated the specific heat and latent heat of a number of substances, and amounts of heat evolved in combustion.  Similarly, in 1840 Swiss chemist Germain Hess formulated the principle that the evolution of heat in a reaction is the same whether the process is accomplished in one-step or in a number of stages.  This known as Hess's law.  With the advent of the mechanical theory of heat in the early 19th century, Hess’s law came to be viewed as a consequence of the law of conservation of energy.
Based on these and other ideas, Berthelot and Danish chemist Julius Thomsen, as well as others, considered the heat evolved in the formation of a compound as a measure of the affinity, or the work done by the chemical forces.  This view, however, was not entirely correct.  In 1847, English physicist James Joule showed that raise the temperature of water by turning a paddle wheel in it, thus showing that heat and mechanical work were equivalent or proportion to each other, i.e. approximately, dW α dQ.  This was a precursory form of the first law of thermodynamics.
By 1865, the German physicist Rudolf Clausius had showed that this equivalence principle needed amendment.  That is, one can use the heat derived from a combustion reaction in a coal furnace to boil water, and use this heat to vaporize steam, and then use the enhanced high pressure energy of the vaporized steam to push a piston.  Thus, we might naively reason that one can entirely convert the initial combustion heat of the chemical reaction into the work of pushing the piston.  Clausius showed, however, that we need to take into account the work that the molecules of the working body, i.e. the water molecules in the cylinder, do on each other as they pass or transform from one step of or state of the engine cycle to the next, e.g. from (P1,V1) to (P2,V2).  Clausius originally called this the “transformation content” of the body, and than later changed the name to entropy.  Thus, the heat used to transform the working body of molecule from one state to the next cannot be used to do external work, e.g. to push the piston.  Clausius defined this transformation heat as dQ = TdS.
Hence, in 1882, after the introduction of this argument by Clausius, the German scientist Hermann von Helmholtz stated, in opposition to Berthelot and Thomas’ hypothesis that chemical affinity is a measure of the heat of reaction of chemical reaction as based on the principle of maximal work, that affinity is not the heat evolved in the formation of a compound but rather it is the largest quantity of work which can be gained when the reaction is carried out in a reversible manner, e.g. electrical work in a reversible cell.  The maximum work is thus regarded as the diminution of the free, or available, energy of the system (Gibbs free energy G at T = constant, P = constant or Helmholtz free energy F at V = constant, P = constant), whilst the heat evolved is usually a measure of the diminution of the total energy of the system (Internal energy).  Thus, G or F is the amount of energy “free” for work under the given conditions.
Up until this point, the general view had been such that: “all chemical reactions drive the system to a state of equilibrium in which the affinities of the reactions vanish”.  Over the next 60 years, the term affinity came to be replaced with the term free energy.  According to chemistry historian Henry Leicester, the influential 1923 textbook Thermodynamics and the Free Energy of Chemical Reactions by Gilbert N. Lewis and Merle Randall led to the replacement of the term “affinity” by the term “free energy” in much of the English-speaking world. 
I hope this helps?  As to a good book, one that I'm reading this week is the 1967 textbook Nonequilibrium Thermodynamics in Biophysics published by Harvard University Press.  It’s written by A. Katchalsky (Polymer Chemistry Department, Institute of Science Rehoveth, Israel) and Peter R. Curran (Biophysical Laboratory, Harvard Medical School, Boston Massachusetts).  I’m about halfway through the book and it is very juicy.  All the derivations are built from the ground up so you don’t miss any key pieces and they are easy to follow.  It shows how the Gibbs free energy equation, in an expanded form, can be applied to very exotic situations, such as when the transport of a substance into muscle tissue causes a chemical reaction, which then does the work of stretching or contracting a muscle fiber.  Very stimulating book!  As to good chemical engineering thermodynamics textbooks, Smith, Van Ness and Abbott’s textbook is good as well as Sandler’s textbook.  Adios: --Sadi Carnot 02:10, 30 July 2006 (UTC)
thread_title: Reply

message: In the Derivation section,
"Thus, Gibbs energy is most useful for thermochemical processes at constant temperature and pressure: both isothermal and isobaric. Such processes don't move on a P-V diagram; and therefore appear to be thermodynamically static."
if the process is isothermal and isobaric, shouldn't it say, "Such processes don't move on a P-T diagram..."?Brian Wowk 21:32, 3 August 2006 (UTC)
replies: text: Yes! The Gibbs function is at constant pressure, so specifically includes pV work preformed in changing the volume of a system. Physchim62 (talk) 16:01, 4 August 2006 (UTC)
thread_title:  Should P-V be P-T ? 

message: Please merge Standard Gibbs free energy change of formation here to get rid of a stub which will likely remain undeveloped and which has been tagged for cleanup for over a year, if it's at all possible.  Thanks. -THB 02:09, 16 October 2006 (UTC)
replies: text: Done, thanks: --Sadi Carnot 23:53, 3 November 2006 (UTC)
thread_title: Merge

message: The data is currently given in terms of (some indeterminate) "cal" — see calorie.  Should be SI.
—DIV (128.250.80.15 (talk) 04:34, 1 April 2008 (UTC)
thread_title: Data

message: I know this may not be the correct place but I need some help with calculating the Enthalpy (ΔH) of a reaction given the following data:
*Mass of salt that dissolved in 5ml water
*Temperature at which it completely dissolves
* Mass of Salt in solution of water
*Mole of Salt in 100 g solution water
*Density of solution at 20 Degrees celcius
*Density of solution at Temperature in which it dissolves
*Volume of 100g of solution
*Molarity of salt
*Equilibrium constant 
Tourskin 19:51, 23 March 2007 (UTC)
thread_title:  Help!!