Gibbs energy interaction

Gibbs transfer energy of an ion i from phase a to p AG g Gibbs energy for ion-solvent interaction in phase a A log P partition coefficient difference between two solvent systems A 0 Galvani potential difference between a and p phases Ag(pi/2 half-wave potential... 

The Gibbs energy of an ion changes on transfer from one solvent to another primarily because the electrostatic interaction between ions and the medium changes as a result of the varying dielecric constant of the solvent. This can be expressed roughly by the Born equation (see Eq. 1.2.7),... 

The difference between the electronic energies of the final and initial states must include the energy of ionization of the ion B(z-1)+ in vacuo (where its ionization potential is complemented by the entropy term TA5/), the interaction energy of the ions Bz+ and B(z-1)+ with the surroundings, i.e. the solvation Gibbs energies, and finally the energy of an electron at the Fermi level in the electrode. These quantities can be expressed most simply... 

Complex formation between a metal ion and a macrocyclic ligand involves interaction between the ion, freed of its solvation shell, and dipoles inside the ligand cavity. The standard Gibbs energy for the formation of the complex, AGjv, is given by the difference between the standard Gibbs... 

The formation of the hydrogen bond between hydroperoxide and polar monomer, for example, methyl acrylate or acrylonitrile, does not influence the rate constant of the reaction of hydroperoxide with the double bond of monomer [101]. The values of the rate constants of the reaction of hydroperoxide with olefins are given in Table 4.13. The effect of multidipole interaction was observed for reactions of hydroperoxide with polyfunctional monomers (see Table 4.14, Ais the Gibbs energy of multidipole interaction in the transition state). 

If the Gibbs energy of adsorption AG-M is considered as independent of the coverage the resulting formula is known as the Langmuir isotherm this assumption is reasonable when the interaction between the adsorbed particles is small. 

For a large number of the more commonly used microscopic solution models it is assumed, as we will see in Chapter 9, that the entropy of mixing is ideal. The different atoms are assumed to be randomly distributed in the solution. This means that the excess Gibbs energy is most often assumed to be purely enthalpic in nature. However, in systems with large interactions, the excess entropy may be large and negative. 

In the two-state model [20,21] the two different species interact and the interaction can be expressed using the regular solution model. Thus the Gibbs energy of the liquid is... 

Assuming this standard state, the AC° value expresses a change in the Gibbs energy of adsorption of one molecule B upon being moved from the hypothetical ideal solution onto the electrode surface. This enables the particle-particle interactions on the surface to be separated from any other interactions and to be included in the term/(/i). 

Therefore the determination of the standard Gibbs energies of adsorption at various symmetrical or unsymmetrical standard states leads directly to derivation of the particle-particle interaction parameter. The same result may be obtained from the difference of AG"" values calculated at zero surface coverage (0 = 0) and at saturated surface coverage (0=1), using Eqs. (30a) and (30b). 

The interdependence of the Gibbs energy of adsorption and the molecular interaction parameter was recently discussed in detail by Karol-czak, who used a six-parameter model. Contrary to the rather general Damaskin model, no relation between the molecular interaction parameter A and AGads was assumed. It was suggested that this is an arbitrary relation dependent on the theoretical model used in fitting experimental data within acceptable experimental errors. 

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