Ion free energy

R. Gomer, and G. Tryson, An experimental determination of absolute half-cell emfs and single ion free energies of solvation, J. Chem. Phys. 66, 4413-4424 (1977). 

Design principles of new sensors for ionic drugs follow from application of potential gjnerjtion theory using three ions M, X and Y, or M, N and Y. Studies of liquid/liquid interface transport identify single-ion free energies of partition as the figures of merit for selectivity and sensitivity. New liquid membranes with sensitivities to 10 mol/1 for bisquaternary muscle relaxants and phenytoin serve as examples. 

These subtleties sometimes lead to a casual view of detailed molecular calculations such as are suggested by Eq. (4.22). If the potential of the phase is always irrelevant to neutral linear combinations of which are thermodynamically measurable, then perhaps it is unimportant to be precise about an assumed value. Our suggestion is that results obtained by molecularly detailed calculations of solvation free energies of single ions are compared and tabulated. Thus, precision and clarity in the assumptions underlying a calculated or tabulated result are important. Indeed, if calculated or tabulated values based upon different assumptions for the potential of the phase were to be combined, it would be essential that the assumptions be precisely known. Nevertheless, an ultimate thermodynamic test of a calculation should be made on thermodynamically measurable combinations of single ion free energies. 

Grunwald et al. (1960), that the enthalpies of transfer from water to DMSO for tetraphenylarsonium cation and the tetraphenylboride anion are equal. They thus derive the single-ion enthalpies of transfer shown in Table 22. We have used the same assumption (cf. Table 5) to derive single-ion free energies of transfer from DMF to various solvents. 

Alkali metal Crystal Charge density radius r [A] [Coulomb/A3] Stokes radiia) of hydrated ions rs[A] Relative size of alkali metal ions Free energy of Rate constant hydration of inner sphere substitution - AGulkcal/mole] A [sec-1] ... 

Acidithiobacillus ferrooxidans anaerobically oxidizes elemental sulfur and formate with ferric ion (Sugio et al., 1985 Pronk et al., 1991a Das et al., 1992). The bacterial oxidation of elemental sulfur and formate with ferric ion is inhibited by HOQNO but not by azide. In the oxidation of elemental sulfur with ferric ion free energy of 75 kcal/S° is liberated, which is enough to support the growth of the bacterium. Thus, the bacterium grows anaerobically by oxidizing elemental sulfur with ferric ion (Pronk et al., 1992). 

The solvation of ions in different solvents is described most satisfactorily in terms of ai le-ion free energies, enthalpies and entropies of solvation. These quantities are related by the well-known Gibbs-Helmholtz equation. 

Single Ion Free Energies of Transfer from Water to Organic Solvents at 25°C ... 

Gomer, R. Tryson, G., An Experimental Determination of Absolute Half-Cell Emf s and Single Ion Free Energies of Solvation. J. Chem. Phys. 1977,66, 4413-4424. 

The index i denotes the states with energy ,/ = e so for nondegenerate states i there is no sum over i. Considering the operator JitA 0) tf 0 in eq. (79) to be the perturbation, one obtains the single-ion free energy (78) in the following form ... 

---