Gibbs energy of partition

It is important to notice that the standard Gibbs energy of transfer refers to the transfer from pure w to pure organic o. It is therefore different from the Gibbs energy of partition, which refers to the transfer between mutually saturated solvents. Nevertheless, in the case of solvents of low miscibility such as water-DCE or water-nitrobenzene, the transferred ion is practically not hydrated by water present in the organic phase, so that... 

Table 18 Standard Molar Gibbs Energy of Partitioning of Alkali Metal Cations from Solvent-Saturated Water to Water-Saturated Solvents ... 

Standard molar Gibbs energy of partitioning (kJ/mol) refers here to the transfer of an ion from solvent-saturated water to water-saturated solvent... 

The liquid junction potential from the organic side may be negligible, owing to the use of a nitrobenzene-water partition system containing tetraethylammonium picrate as the salt bridge. The mobilities of both ions in nitrobenzene are similar, and they have similar Gibbs energies of... 

A relative scale of the standard Gibbs energies of ion transfer or the standard ion transfer potentials can be established based on partition and solubility measurements. The partition eqnilibrium of the electrolyte can be characterized by a measnrable parameter, the partition coefficient P x-... 

TABLE 32.2 Standard Gibbs Energy of Transfer and Standard Ion Transfer Potentials for Ion Transfer Between Water and Nitrobenzene Derived from Partition Measurements... 

In the framework of the mobile order and disorder (MOD) theory five components contribute most to the Gibbs free energy of partitioning of a solute in a biphasic system of two essentially immiscible solvents [23] ... 

For symmetrical electrolytes, of, e.g., type 1 1, such a liquid-liquid interface, in equilibrium, is described by the standard Galvani potential, usually called the distribution potential. This very important quantity can be expressed in the three equivalent forms, i.e., using the ionic standard potentials, or standard Gibbs energies of transfer, and employing the limiting ionic partition coefficients [3] ... 

For thermochemical uses, an expression for the integral Gibbs energy of formation of the compound ABC can be derived by integration of eq. (9.104), but in order to show clearly some of the main implications of the model a more detailed analysis starting from the partition function is preferred [23]. 

The standard Gibbs energy of the ion transfer is a direct measurement of lipophilicity, and is related to the standard partition coefficient of the ion in the biphasic system through the following equation ... 

When a system at specified T and P contains two species and one of them is in equilibrium with that species in a reservoir through a semipermeable membrane, the transformed Gibbs energy of the system is calculated from the semigrand partition function F(7( P, /q, N2) by use of... 

Rl/+X from w to o, a s are the mean activities, y s are the mean activity coefficients, and cRX s are the equilibrium electrolyte concentrations. A non-thermodynamic assumption has to be introduced to construct the scale of the inner (Galvani) potential differences from the partition measurements. The most commonly used hypothesis is that the tetraphenylarsonium cation (Ph4As+) and the tetraphenylborate anion (PI14 B ) have equal standard Gibbs energies of transfer for any combination of two solvents [iv]. This assumption enables the evaluation of AG 1 and AG j from the partition mea-... 

This equation shows that, contrary to the partition of neutral species for which log PN is a unique quantity related by Eq. (12) to its standard Gibbs energy of transfer, the partition of ionic species is potential dependent, and log P10 represents the proportion of ions present in each phase if the interface is not polarized ... 

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