Gibbs free energy of transfer

For two relatively immiscible solvents log P can be considered [1] proportional to the molar Gibbs free energy of transfer between octanol and water ... 

In principle, Gibbs free energies of transfer for trihalides can be obtained from solubilities in water and in nonaqueous or mixed aqueous solutions. However, there are two major obstacles here. The first is the prevalence of hydrates and solvates. This may complicate the calculation of AGtr(LnX3) values, for application of the standard formula connecting AGt, with solubilities requires that the composition of the solid phase be the same in equilibrium with the two solvent media in question. The other major hurdle is that solubilities of the trichlorides, tribromides, and triiodides in water are so high that knowledge of activity coefficients, which indeed are known to be far from unity 4b), is essential (201). These can, indeed, be measured, but such measurements require much time, care, and patience. 

As indicated in the previous section, the derivation of Gibbs free energies of transfer, and thence of entropies of transfer, from trichloride... 

The HSAB (hard and soft acids and base) principle is that hard acids prefer to interact with a hard base, and soft acids with soft bases. Hard bases are not polarizable, and inclnde those with 0-donor atoms. Soft bases are more polarizable, and inclnde S-donor bases. Solvent hardness/softness can be assessed by comparing the Gibbs free energy of transfer of a soft cation like Ag from hard water to the solvent with the Gibbs free energy of transfer of similarly sized hard cations like Na and K. Table 3.9 shows some solvents listed in increasing softness. ... 

Standard Gibbs Free Energy of Transfer of n-Bu4NBr from Water to Water-Organic Solvent Mixtures as Deduced from Precise Vapor Pressure Measurements at 298.15°K... 

Incremental Gibbs free energy of transfer from n-octanol to water... 

Note that RT ln(P/P0), i.e., 2303RTtt, is the incremental Gibbs free energy of transfer of the group R from n-octanol to water (relative to the hydrogen atom H). Some values of 77 are listed in Table 11.4. Points to be noted are ... 

The factor FHA in equation (94) can be replaced by F a if it is permissible to assume that Gibbs free energies of transfer are linear functions of n. With this simplification the consequences of the transfer effect are reduced to the inclusion of a single parameter in the expression for the solvent isotope effect. 

For purely electrostatic solute/solvent interactions, the Kirkwood equation, Eq. (4-27) [56], is applicable, which relates the standard molar Gibbs free energy of transfer of spherical dipolar molecules of radius r and dipole moment // from the gas phase (fir = 1) to a continuous medium of relative permittivity r-... 

AGt° is the standard Gibbs free energy of transfer of the ionic surfactant between water and the solvent s AG °mlc is the same quantity defined between a micelle in water and in solvent s. 

Figure I. Single-ion standard Gibbs free energy of transfer from water to water + acetone mixtures based on S.F.T. calculations for the tetrabutylammonium ion (mole-fraction...

Rodnguez O, Madeira PP, Macedo EA (2008) Gibbs free energy of transfer of a methylene group in buffer ionic hquid biphasic systems. Ind Eng Chem Res 47 5165-5168... 

The product, —AF0F, in which A 0 is the difference of any two of these standard potentials, is the Gibbs free energy of transfer of hydrogen chloride, at infinite dilution, from one solvent to another. 

The standard potential of transfer for an individual ion, A cp , is not amenable to thermodynamic measurement. Its value can be determined by measuring the distribution ratio of its salt, for which the Gibbs free energy of transfer of the counterion is already known. From the experimentally accessible partition coefficient of the salt, the standard Gibbs free energy of transfer of the salt, AG aI7P, from phase a to phase p is calculated as... 

The position of chemical equilibria as well as the direction of all spontaneous chemical change is determined by free energies. The partition constant of a sample molecule between two phases A and is directly related to the Gibbs free energy of transfer [6]... 

Finally, because of its definition, the separation factor for two compounds is related to the difference between the corresponding Gibbs free energies of transfer from one phase to the other ... 

---