Gibbs free energy of solvation

Within the framework of the same dielectric continuum model for the solvent, the Gibbs free energy of solvation of an ion of radius and charge may be estimated by calculating the electrostatic work done when hypothetically charging a sphere at constant radius from q = 0 q = This yields the Bom equation [13]... 

Kirkwood generalized the Onsager reaction field method to arbitrary charge distributions and, for a spherical cavity, obtained the Gibbs free energy of solvation in tenns of a miiltipole expansion of the electrostatic field generated by the charge distribution [12, 1 3]... 

As with SCRF-PCM only macroscopic electrostatic contribntions to the Gibbs free energy of solvation are taken into account, short-range effects which are limited predominantly to the first solvation shell have to be considered by adding additional tenns. These correct for the neglect of effects caused by solnte-solvent electron correlation inclnding dispersion forces, hydrophobic interactions, dielectric saturation in the case of... 

M. D. Tissandier, K.A. Cowen, W.Y. Feng, E. Gundlach, M. H. Cohen,A. D. Earhart, J. V Coe, T. R. Tuttle Jr. The Proton s Absolute Aqueous Enthalpy and Gibbs Free Energy of Solvation from Cluster-Ion Solvation Data. J. Phys. Chem. A 1998, 102, 7787-7794. 

The Gibbs free energy of solution is the difference between the Gibbs free energy of solvation of the solute in the solvent and any Gibbs free energy of interaction in the pure solute that are lost on dissolution, if it is a solid, a liquid, or a nondilute gas. 

The differences in solvation of the reactants and the products constitute in general the major difference between the driving force for the equilibrium reaction in solution and that in the gas phase. The molar Gibbs free energy of solvation for any species I that participates in the equilibrium in a given solvent S can be written as... 

In the present context, the solvation of a solvent molecule in its own liquid (i.e., condensation from the vapour, the opposite of evaporation) is of interest, and molar quantities are employed, rather than quantities pertaining to a single particle (Ben-Naim and Marcus 1984). The Gibbs free energy of solvation of a solvent in itself is ... 

Returning to the solvation of gaseous or liquid solutes in solvents, the Gibbs free energy of solvation is given by ... 

A comparison of anion solvation by methanol, a protic solvent, and dimethylformamide, a dipolar aprotic solvent, is instructive. The electrostatic contribution, d/i , to the Gibbs free energy of solvation per mole of an ion is sometimes estimated quite successfully (Stokes, 1964) from the Bom model, in which a charged sphere of radius r is transferred from vacuum to a medium of uniform dielectric constant, c. The Bom equation (17) suggests that an anion should be similarly solvated in methanol and in DMF, because these solvents have effectively the same dielectric constant (33-36). The Born equation makes no allowance for chemical interactions, such as hydrogen-bonding and mutual... 

The Henry s law constants (77) for triazine-derived herbicides have been calculated using quantum-chemical solvation models, SM2, SMS, PCM-DFT, and CPCM-DFT, and their performances have been discussed. The results showed considerable differences in performance among the different levels of theory. The differences were discussed in terms of the different contributions, electrostatic and nonelectrostatic, to Gibbs free energy of solvation <2003JCI1226>. 

Acidity and basicity in the gaseous phase are intrinsic properties of individual molecules. For substances in the liquid state these properties belong to the entire phase and have less localised meanings. The transfer of a reaction from the gaseous to the liquid phase involves the Gibbs free energies of solvation of reactants and products... 

The medium effect is proportional to the reversible work of transfer of one mole of protons from infinite dilution in water to infinite dilution in solvent S. A negative value of the medium effect indicates that the proton is more stable in S, a positive value that it is more stable in water. The medium effect will thus depend on the relative basicities of water and S, basicity being understood to include not only the proton affinities of the gaseous solvent and water molecules but also the Gibbs free energies of solvation of the ions in water and in S,... 

The largest source of error in pK calculations is the change in Gibbs free energy of solvation calculation for the reaction, which is based on the type of solvation model used and the specific level of theory [8.11.15.39.55]. The... 

Along with deciding whether to use implicit or implicit-explicit solvent models, a specific level of theory and basis set must be used for the calculation of the change in Gibbs free energy of solvation. Similar to the gas phase Gibbs free energy, there are a variety of methods and it can be difficult to determine what combination is the most accurate. 

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