Browsing by Author "Liszi, János"

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Calculations on Ionic Solvation Part 1.—Free Energies of Solvation of Gaseous Univalent Ions Using a One-layer Continuum Model
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (07), 1978) Abraham, Michael H.; Liszi, János
    The electrostatic free energy of solvation of an ion has been calculated using a model in which an ion of radius a and dielectric constant εi= 1 is surrounded by a solvent layer of thickness (b–a) and dielectric constant ε1, immersed in the bulk solvent of dielectric constant ε0. The electrostatic energy is combined with the nonelectrostatic free energy of solvation, obtained from experimental data on the free energy of solution of gaseous non-polar solutes, to yield the total free energy of solvation of a gaseous ion in a solvent. It is found that when a is taken as the ionic crystal radius, (b–a) as the solvent radius and ε1= 2 there is excellent agreement with experiment for the solvation of gaseous univalent cations and anions in the solvents, 1,1-dichloroethane, 1,2-dichloroethane, tetrahydrofuran, 1,2-dimethoxyethane, ammonia, acetone, acetonitrile, nitromethane, 1-propanol, ethanol, methanol and water. Limited data suggest that the method can also be applied to solution of ions in benzene, bromobenzene, chlorobenzene, ethyl benzoate, ethyl acetate and nitrobenzene.
  • No Thumbnail Available
    Item
    Calculations on Ionic Solvation Part 2. Entropies of Solvation of Gaseous Univalent Ions using a One-layer Continuum Model
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (09-12), 1978) Abraham, Michael H.; Liszi, János
    The electrostatic entropy of solvation of gaseous ions has been calculated using our previous model in which the ion is surrounded by a local solvent layer, immersed in the bulk solvent. The calculated electrostatic entropy is combined with the nonelectrostatic entropy of solvation, obtained from experimental data on entropies of solution of gaseous nonpolar solutes, to yield the total entropy of solvation of a gaseous ion. The only new parameters involved in the calculations are the variations with temperature of the solvent bulk dielectric constant (a known property) and the dielectric constant in the local solvent layer. We found that if the latter parameter is taken as –0.001 60 (a reasonable value for a region of low dielectric constant), there is excellent agreement with experiment for entropies of solvation of univalent cations and anions in a wide variety of aprotic solvents, and for entropies of transfer of these ions between aprotic solvents. Since no adjustable parameters are used in the calculations, the method can be used to predict entropies of solvation or of transfer in aprotic solvents. Agreement with experiment is not found for solvation entropies of ions in hydrogen bonded solvents.