Showing papers on "Gibbs–Helmholtz equation published in 2010"
TL;DR: In this article, the Gibbs equation was deduced from the identity of the chemical potential of each component, including the solvent, in the bulk and the surface phase, and relations were obtained between surface pressure, adsorptions and molar fractions.
Abstract: From the identity of the chemical potential of each component, including the solvent, in the bulk and the surface phase, the Gibbs equation is deduced. Relations are obtained between surface pressure, adsorptions and molar fractions in the bulk phase. The equations hold both for adsorbed and for spread films. A penetrated film is also considered. The relation between molar fraction and surface pressure was tested for the system Na-laurate and sapoalbin, having very different saturation adsorption values. Agreement between theory and experiment is satisfactory.
71 citations
TL;DR: The Legendre-transformed Gibbs energy change for a biochemical reaction, Delta(r)G', is shown to be equal to the nontransformed Gibbs energies of reaction,Delta( r)G, of any single reaction involving selected chemical species of the biochemical system.
Abstract: The Legendre-transformed Gibbs energy change for a biochemical reaction, Delta(r)G', is shown to be equal to the nontransformed Gibbs energy change, Delta(r)G, of any single reaction involving selected chemical species of the biochemical system. These two Gibbs energies of reaction have hitherto been thought to have different values. The equality of the quantities means that a substantial part of biochemical and chemical thermodynamics, previously treated separately, can be treated within a unified thermodynamic framework. An important consequence of the equality of Delta(r)G and Delta(r)G' is that the Gibbs energy change of many enzyme reactions can be quantified without specifying which chemical species is the active substrate of the enzyme. Another consequence is that the transformed standard Gibbs energy change of a reaction, Delta(r)G'(0), can be calculated by a simple analytical expression, rather than the complex computational methods of the past. The equality of the quantities is restricted to Gibbs energy changes and does not apply to enthalpy or entropy changes.
23 citations
TL;DR: In this paper, the Gibbs energy of formation from Cd and Te2(g) and from the solid or liquid elements as a function of temperature was derived for CdTe(c).
Abstract: The high temperature heat capacity, Gibbs energy of formation, and standard enthalpy and entropy of formation at 298 K are combined with thermodynamic data for Cd and revised data for Te to provide an internally consistent data set for CdTe(c). Equations are given for the Gibbs energy of formation from Cd(g) and Te2(g) and from the solid or liquid elements as a function of temperature. These give values similar to those used before. However, the derived enthalpy and entropy of formation are significantly different due to a revised heat capacity for CdTe(c). The standard enthalpy and entropy of formation at 298.15 K from the gases are −293262 J/mol and −200.593 J/mol K, respectively. From the solid elements they are −100270 and −4.5334.
12 citations
TL;DR: In this paper, the authors measured the heat capacity of YVO4 by adiabatic calorimetry in the region of 13.11 −347.14 K. The values of thermodynamic functions (the entropy, enthalpy change and reduced Gibbs function) were calculated using smoothed heat capacity values.
Abstract: The heat capacity of YVO4 was measured by adiabatic calorimetry in the region of 13.11–347.14 K. The values of thermodynamic functions (the entropy, enthalpy change and reduced Gibbs function) were calculated using smoothed heat capacity values. The value of the Gibbs energy of formation from simple compounds was calculated.
5 citations
TL;DR: In this paper, the entropy and Gibbs free energy of the formation of C 60 Cl 30 · 0.09 Cl 2 have been derived for a crystal solvate of fullerene chloride.
2 citations
TL;DR: In this paper, it is shown that application of theory to experiments requires several intermediate layers where theory and experiment commingle, and in the process, it is also shown that the relation between Gibbs energy and the equilibrium constant is deduced from fundamental laws of thermodynamics.
Abstract: Varieties of chemical and phase equilibria are controlled by the minimum Gibbs energy principle, according to which the Gibbs energy for a system will have the minimum value at any given temperature and pressure. It is understood that the minimum is with respect to all nonequilibrium states at the same temperature and pressure. The abstract relation between Gibbs energy and the equilibrium constant is deduced from fundamental laws of thermodynamics. However, actual use of this relation calls for the Gibbs energy as a function of concentrations of the chemicals. Since thermodynamics is formulated without any reference to materials, how does one get that relation? This article provides the answer, and in the process shows that application of theory to experiments requires several intermediate layers where theory and experiment commingle.
2 citations
14 Sep 2010
TL;DR: Goldberg et al. as discussed by the authors presented a table of the standard conditions of enzyme characterizations (ESCEC) for biochemical reactions, which can be used to construct a thermodynamic network, i.e., a system of linear equations that can be solved for the desired formation properties.
Abstract: Both organic and inorganic chemistry have benefited greatly from the availability of tables of standard enthalpies of formation DfH, standard Gibbs energies of formation DfG0, and standard entropies S These tables of standard thermodynamic properties allow the user to calculate values of enthalpy changes DrH0, Gibbs energy changes DrG0, equilibrium constants K, and entropy changes DrS for any reaction in which these standard thermodynamic properties are known for all of the reactants and products Thus, it is not necessary that actual measurements have been performed on the reaction of interest While several tables of standard thermodynamic properties have been prepared for biochemical substances, they are not as extensive as the corresponding tables for organic and inorganic substances or as extensive as they might be if all of the available experimental results in the literature 213 http://wwwbeilstein-institutde/ESCEC2009/Proceedings/Goldberg/Goldbergpdf Experimental Standard Conditions of Enzyme Characterizations, September 13 – 16, 2009, Rudesheim/Rhein, Germany 1 This is an official contribution of the National Institute of Standards and Technology and is not subject to copyright in the United States Certain commercial items are identified in this paper Such identification is not intended to imply recommendation or endorsement by the National Institute of Standards and Technology (NIST), nor is it intended to imply that these items are necessarily the best available for the purpose had been utilized Nevertheless, comprehensive tables could be produced by utilizing all of the data {apparent equilibrium constants K’ and calorimetrically determined enthalpies of reaction DrH(cal)} in the Thermodynamics of Enzyme-catalyzed Reactions Database [1] together with related property values such as standard enthalpies of combustion, entropies and heat capacities, solubilities, enthalpies of solution, pKs, and enthalpies of binding for the substances of interest This large set of property values can be used to establish a thermodynamic network, i e, a system of linear equations that can be solved for the desired formation properties Such an undertaking requires extensive literature work, a substantial amount of analysis and computation on the results of the individual studies, and a careful fitting together of the property values by means of a judicious weighting of the property values It can be viewed as a very large ‘‘jig-saw puzzle’’ of information But the proper construction of such a network would serve to bring together a large body of related property values and would be of immense practical value to the scientific community In addition to the aforementioned utility of the standard thermodynamic properties, there are also the following additional benefits: (1) the consistency or lack of consistency of related results are made visible and needed measurements are identified straightforwardly; (2) the calculated formation properties can be easily updated and revised by a relatively quick calculation so as to allow for the inclusion of both new measurements, remeasurements, corrections, and a revised weighting of results; and (3) the calculated formation properties can, based on structural similarity, serve as the basis for the estimation of property values that have not yet been measured The table of formation properties and the estimation procedures can also be embedded in computer codes which a user could use to calculate the position of equilibrium of numerous biochemical reactions The aim of this chapter is to briefly describe the use of these tables, how they are prepared, the current status of existing tables that pertain to biochemical reactions, and to provide a vision of what is possible Introduction This chapter is an extension of the chapter [2] that I contributed to the Proceedings of the 3 International Beilstein Workshop on Experimental Standard Conditions of Enzyme Characterizations (ESCEC) An important point made in that chapter was that one can use an equilibrium model together with values of equilibrium constants K and standard enthalpies of reaction DrH0 for chemical reactions (i e, reactions that involve specific species; both atoms and charges must balance in chemical reactions) to calculate the proper214
2 citations
TL;DR: It is suggested to introduce an information term into the Gibbs thermodynamic equation in the case of living systems to describe the behavior of organisms by means of such an approach.
Abstract: It is suggested to introduce an information term into the Gibbs thermodynamic equation in the case of living systems. The possibility of describing the behavior of organisms by means of such an approach is shown.
1 citations
25 Jan 2010
TL;DR: In this paper, the Gibbs energy of binary and ternary systems of alkali metals Cs-Na, K-Na and K-K-Na was determined using partial pressures of the components measured according to the effusion method.
Abstract: A detailed procedural analysis is given and results of implementation of the new version of the effusion method for determining the Gibbs energy (thermodynamic activity) of binary and ternary systems of alkali metals Cs-Na, K-Na, Cs-K, and Cs-K-Na are presented. The activity is determined using partial pressures of the components measured according the effusion method by the intensity of their atomic beams. The pressure range used in the experiment is intermediate between the Knudsen and hydrodynamic effusion modes. A generalized version of the effusion method involves the pressure range beyond the limits of the applicability of the Hertz-Knudsen equation. Employment of this method provides the differential equation of chemical thermodynamics; solution of this equation makes it possible to construct the Gibbs energy in the range of temperatures 400 ≤ T ≤ 1200 K and concentrations 0 ≤ xi ≤ 1.
01 Jan 2010
TL;DR: In this paper, the Gibbs energy of a chemical in solution and a formula for calculating Gibbs energy in a chemical reaction are presented. But they do not consider the effects of different concentrations.
Abstract: I already said that it is important to understand and to know how to calculate and prepare different concentrations. Many chemical reactions – and all the biochemical reactions that run our bodies – take place in a solution. Now we are going to put together a formula for the Gibbs energy of a chemical in solution and a formula for calculating the Gibbs energy in a chemical reaction.
01 Jan 2010
TL;DR: In this paper, the Gibbs free energy (GFE) was used to calculate the entropy of mixing in a solution of urea, O=C(NH2)2, in water, H2O.
Abstract: We have shown that when two things are mixed together we can calculate the entropy of mixing. We can also calculate the concentration of this mixture, as we did in the previous three examples. A most complete description of the chemicals and their mixtures is by using Gibbs free energy (we say it is free because it does not contain any pV work, like when we are working with gases). Let us think for a moment of the following mixture: a solution of urea, O=C(NH2)2, in water, H2O. Water, a liquid, is present in larger quantity so we call it the solvent.