ΔGθ, ΔHθ, ΔSθ de transfert de H2O et du couple H+, OH− de l'eau à ses mélanges contenant jusqu'à 40% de EtOH, tert-BuOH, DMSO, acétone et urée à 25 °C

1975 ◽  
Vol 53 (3) ◽  
pp. 455-462 ◽  
Author(s):  
Henri Gillet ◽  
Lévon Avédikian ◽  
Jean-Pierre Morel
Keyword(s):  
Dielectric Constant ◽  
Free Energy ◽  
Alkali Halides ◽  
Ion Pair ◽  
Pure Liquid ◽  
Thermodynamic Quantities ◽  
Simple Correlation ◽  
Organic Mixtures ◽  
The Media ◽  
Isobaric Expansion

We have measured the heat of neutralization of dilute solutions of HCl in aqueous–organic mixtures containing up to 40% by weight of t-BuOH, DMSO, acetone, and urea; autoprotolysis constants of the mixtures H2O–DMSO and H2O–urea also were determined. Thus the usual thermodynamic quantities ΔGθ, ΔHθ, and ΔSθ could be determined for the dissociation of water in these mixtures. The results for the H2O-urea mixtures must be accepted with caution because the dissociation of urea itself is not negligible compared to that of water. Using various literature data we have calculated values of the Gibbs free energy and the enthalpy for the transfer of a molecule of water from the pure liquid to the mixtures noted above. (We also have calculated for these mixtures the coefficients of isobaric expansion and those for the variation with temperature of the dielectric constant.) In addition, the values for the transfer of the ion pair H+, OH− have been determined as well as those for the transfer from water to H2O–EtOH mixtures. These are com pared to those already known for HCl and the alkali halides. It is not possible to establish a simple correlation between the differing variations of these quantities with the structural prop erties usually considered to exist in the media studied. [Journal translation]

scholarly journals Solubility of Polar and Non-Polar Aromatic Molecules in Subcritical Water: The Role of the Dielectric Constant

2019 ◽  
Author(s):  
Nuno Galamba ◽  
Alexandre Paiva ◽  
Susana Barreiros ◽  
Pedro Simões
Keyword(s):  
Dielectric Constant ◽  
Free Energy ◽  
High Temperatures ◽  
High Pressures ◽  
Subcritical Water ◽  
Hot Water ◽  
Model Systems ◽  
Pure Liquid ◽  
Hydration Free Energy ◽  
Polar Solutes

Liquid water at temperatures above the boiling point and high pressures, also known as pressurized hot water, or subcritical water (SBCW), is an effective solvent for both polar and non-polar organic solutes. This is often associated to the decrease of water's dielectric constant at high temperatures, apparently allowing water to behave like an organic solvent. The decrease of the solubility at high pressures, in turn, is explained by a mild increase of the dielectric constant of water. Nevertheless, the relationship between the dielectric constant of water, hydration, and the solubility of polar and non-polar molecules in SBCW, remains poorly understood. Here, we study through molecular dynamics, the hydration thermodynamic parameters and the solubility of non-polar and polar aromatic model systems, for which a solubility increase in SBCW is observed. We show that the temperature dependence of the hydration free energy of the model non-polar solutes is nonmonotonic, exhibiting a solute size independent maximum at ~475 K, above which hydration becomes entropically favorable and enthalpically unfavorable. The monotonic increase of the solubility, separated here in hydration and vaporization or sublimation components of the pure liquid or solid solute, respectively, is, in turn, related to the temperature increase of the latter, and only to a minor extent with the decrease of the hydration free energy above ~475 K, via the hydration entropy. A solubility increase or decrease is also found at high pressures for different solutes, explained by the relative magnitude of the hydration and the vaporization or sublimation components of the solubility. For the model solid polar system studied, the hydration free energy increases monotonically with the temperature, instead, and the solubility increase is caused by the decrease of the sublimation component of the solubility. Thus, despite of the observed increase of the hydration free energy with pressure, related to the entropic component decrease, our results indicate that the dielectric constant plays no significant role on the solubility increase of non-polar and polar solutes in SBCW, opposite to the dielectric constant picture. The structure of water next to the solutes is also investigated and a structural enhancement at room temperature is observed, resulting in significantly stronger pair interactions between a water molecule and its third and fourth nearest water neighbors. This structural and energetic enhancement nearly vanishes, however, at high temperatures, contributing to a positive hydration entropy. <br>

scholarly journals Solubility of Polar and Non-Polar Aromatic Molecules in Subcritical Water: The Role of the Dielectric Constant

2019 ◽  
Author(s):  
Nuno Galamba ◽  
Alexandre Paiva ◽  
Susana Barreiros ◽  
Pedro Simões
Keyword(s):  
Dielectric Constant ◽  
Free Energy ◽  
High Temperatures ◽  
High Pressures ◽  
Subcritical Water ◽  
Hot Water ◽  
Model Systems ◽  
Pure Liquid ◽  
Hydration Free Energy ◽  
Polar Solutes

Liquid water at temperatures above the boiling point and high pressures, also known as pressurized hot water, or subcritical water (SBCW), is an effective solvent for both polar and non-polar organic solutes. This is often associated to the decrease of water's dielectric constant at high temperatures, apparently allowing water to behave like an organic solvent. The decrease of the solubility at high pressures, in turn, is explained by a mild increase of the dielectric constant of water. Nevertheless, the relationship between the dielectric constant of water, hydration, and the solubility of polar and non-polar molecules in SBCW, remains poorly understood. Here, we study through molecular dynamics, the hydration thermodynamic parameters and the solubility of non-polar and polar aromatic model systems, for which a solubility increase in SBCW is observed. We show that the temperature dependence of the hydration free energy of the model non-polar solutes is nonmonotonic, exhibiting a solute size independent maximum at ~475 K, above which hydration becomes entropically favorable and enthalpically unfavorable. The monotonic increase of the solubility, separated here in hydration and vaporization or sublimation components of the pure liquid or solid solute, respectively, is, in turn, related to the temperature increase of the latter, and only to a minor extent with the decrease of the hydration free energy above ~475 K, via the hydration entropy. A solubility increase or decrease is also found at high pressures for different solutes, explained by the relative magnitude of the hydration and the vaporization or sublimation components of the solubility. For the model solid polar system studied, the hydration free energy increases monotonically with the temperature, instead, and the solubility increase is caused by the decrease of the sublimation component of the solubility. Thus, despite of the observed increase of the hydration free energy with pressure, related to the entropic component decrease, our results indicate that the dielectric constant plays no significant role on the solubility increase of non-polar and polar solutes in SBCW, opposite to the dielectric constant picture. The structure of water next to the solutes is also investigated and a structural enhancement at room temperature is observed, resulting in significantly stronger pair interactions between a water molecule and its third and fourth nearest water neighbors. This structural and energetic enhancement nearly vanishes, however, at high temperatures, contributing to a positive hydration entropy. <br>

System of thermodynamic quantities in the McMillan-Mayer solution theory

1985 ◽  
Vol 50 (4) ◽  
pp. 791-798 ◽  
Author(s):  
Vilém Kodýtek
Keyword(s):  
Free Energy ◽  
Generating Function ◽  
Simple Form ◽  
Unit Volume ◽  
Thermodynamic Quantities ◽  
Solution Theory ◽  
Pure Solvent ◽  
Second Derivatives ◽  
Definition Of ◽  
Derivatives Of

The McMillan-Mayer (MM) free energy per unit volume of solution AMM, is employed as a generating function of the MM system of thermodynamic quantities for solutions in the state of osmotic equilibrium with pure solvent. This system can be defined by replacing the quantities G, T, P, and m in the definition of the Lewis-Randall (LR) system by AMM, T, P0, and c (P0 being the pure solvent pressure). Following this way the LR to MM conversion relations for the first derivatives of the free energy are obtained in a simple form. New relations are derived for its second derivatives.

Kinetics of Ion-Pair Effect of Aquation of Bromopentaammine Cobalt(III) Complex in Different Dicarboxylate Media

2011 ◽  
Vol 324 ◽  
pp. 166-169 ◽  
Author(s):  
Farah Zeitouni ◽  
Gehan El-Subruiti ◽  
Ghassan Younes ◽  
Mohammad Amira
Keyword(s):  
Free Energy ◽  
Solvent Effect ◽  
Compensation Effect ◽  
Ion Pairing ◽  
Reaction Rates ◽  
Ion Pair ◽  
Free Energy Of Activation ◽  
Different Types ◽  
Different Temperatures ◽  
Kinetics Of

The rate of aquation of bromopentaammine cobalt(III) ion in the presence of different types of dicarboxylate solutions containing tert-butanol (40% V/V) have been measured spectrophotometrically at different temperatures (30-600°C) in the light of the effects of ion-pairing on reaction rates and mechanism. The thermodynamic and extrathermodynamic parameters of activation have been calculated and discussed in terms of solvent effect on the ion-pair aquation reaction. The free energy of activation ∆Gip* is more or less linearly varied among the studied dicarboxylate ion-pairing ligands indicating the presence of compensation effect between ∆Hip* and ∆Sip*. Comparing the kip values with respect of different buffers at 40% of ter-butanol is introduced.

The transmission of polar effects. Part VII. A proton magnetic resonance spectra study of substituted mesitylenes, durenes, anthracenes, and triptycenes

1968 ◽  
Vol 46 (24) ◽  
pp. 3903-3908 ◽  
Author(s):  
Keith Bowden ◽  
J. G. Irving ◽  
M. J. Price
Keyword(s):  
Dielectric Constant ◽  
Free Energy ◽  
Carbon Tetrachloride ◽  
Field Effect ◽  
Proton Magnetic Resonance ◽  
Chemical Shifts ◽  
Linear Free Energy ◽  
Solvent Dependence ◽  
Similar Dependence ◽  
Energy Relations

The chemical shifts of the ring protons in a series of monosubstituted mesitylenes and durenes, and of the 10-protons of a series of 9-substituted triptycenes and anthracenes have been measured in dimethyl sulfoxide, acetone, 2-methoxyethanol, and carbon tetrachloride. The solvent dependence of the substituent chemical shifts has been analyzed by linear free energy relations. The systems all show similar dependence which increases with increasing dielectric constant of the solvent. This does not result from the field effect being transmitted through the medium, but appears to arise from the formation of a hydrogen-bonded interaction between the solvent and the hydrogen of the solute. The substituent chemical shifts appear to arise from contributions from substituent field, resonance, magnetic anisotropy, and solvent effects.

Higher Order Conditional Probabilities and Thermodynamics of Binary Molten Alloys

1997 ◽  
Vol 11 (02n03) ◽  
pp. 93-106 ◽  
Author(s):  
O. Akinlade
Keyword(s):  
Free Energy ◽  
Experimental Evidence ◽  
Cluster Model ◽  
Excess Free Energy ◽  
Higher Order ◽  
Thermodynamic Quantities ◽  
Equiatomic Composition ◽  
Conditional Probabilities ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

The recently introduced four atom cluster model is used to obtain higher order conditional probabilities that describe the atomic correlations in some molten binary alloys. Although the excess free energy of mixing for all the systems studied are almost symmetrical about the equiatomic composition, most other thermodynamic quantities are not and thus, the study enables us to explain the subtle differences in their physical characteristics required to describe the mechanism of the observed strong heterocoordination in Au–Zn or homocoordination in Cu–Ni within the same framework. More importantly, we obtain all calculated quantities for the whole concentration range thus complimenting experimental evidence.

scholarly journals Homogenization of composite ferromagnetic materials

2015 ◽  
Vol 471 (2182) ◽  
pp. 20150365 ◽  
Author(s):  
François Alouges ◽  
Giovanni Di Fratta
Keyword(s):  
Free Energy ◽  
Ferromagnetic Material ◽  
Energy Functional ◽  
Ferromagnetic Materials ◽  
Rigorous Derivation ◽  
Free Energy Functional ◽  
Landau Free Energy ◽  
Ferromagnetic Body ◽  
The Media

The objective of this paper is to perform, by means of Γ - convergence and two-scale convergence , a rigorous derivation of the homogenized Gibbs–Landau free energy functional associated with a composite periodic ferromagnetic material, i.e. a ferromagnetic material in which the heterogeneities are periodically distributed inside the media. We thus describe the Γ -limit of the Gibbs–Landau free energy functional, as the period over which the heterogeneities are distributed inside the ferromagnetic body shrinks to zero.

Modelling of interactions in solutions: alkali halides in DMSO

1979 ◽  
Vol 57 (5) ◽  
pp. 538-551 ◽  
Author(s):  
Peeter Kruus ◽  
Barbara E. Poppe
Keyword(s):  
Reasonable Agreement ◽  
Minimum Energy ◽  
Alkali Halides ◽  
Ion Pair ◽  
Point Of View ◽  
Ion Solvation ◽  
Solvation Energies ◽  
Solvent Molecules ◽  
A Charge ◽  
Energy Configurations

A model of solutions of alkali halides in DMSO is developed. Each ion is described by a radius, a charge, a polarizability, and an exponential repulsion parameter. Each molecule is described by a polarizability, charges, 6-12 energy parameters, and 6-12 distance parameters centered on each of the 10 atoms in the molecule. The model is applied to calculate (i) the vaporization energy of solvent molecules, (ii) single ion solvation energies and configurations of the solvating molecules, and (iii) the energy as a function of reaction coordinate for the formation of an ion pair. The energies and configurations are obtained by allowing the systems to relax to minimum energy configurations by allowing motion of the molecules. The results of (i) give a vaporization energy 60% of the experimental. The results of (ii) give solvation energies in reasonable agreement with the experimental, and configurations which are reasonable from the point of view of mobilities of ions. The results of (iii) show the presence of a distinct solvent separated ion pair which actually has an energy lower than the contact ion pair. Advantages and problems involved in using this approach to model solutions are discussed.

Variation of the Dielectric Constant of the Alkali Halides with Pressure

Nature ◽  
1962 ◽  
Vol 193 (4822) ◽  
pp. 1275-1276 ◽  
Author(s):  
G. J. HILL
Keyword(s):  
Dielectric Constant ◽  
Alkali Halides
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