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    Ionic Solvation in Water4-Co-solvent Mixtures Part 5: Free Energies of Transfer of Large Single Ions from Water into Water + Methanol with the “ Neutral ” Component Removed
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (3), 1978) Wells, Cecil F.
    Values for the change in proton affinity, ΔPa, of large molecules on transferring them from water into mixtures of water with methanol have been calculated. –ΔPa for anions and ΔPa for cations represent an elimination of the non-electrostatic or “neutral” component from the free energy of transfer of the ion i, ΔG°t(i). Although plots of –ΔPa against reciprocal of dielectric constant are linear for the anions, the values of their slopes show that there is a structural component of this “electrostatic” free energy, ΔG°t(i)e, in addition to the Born contribution. ΔG°t(F–) is calculated from data newly available, and ΔG°t(halide) values are compared with ΔG°t(i)e values for the large ions. The negative values for ΔG°t(i)e for large cations confirm that there is a contribution from structural changes in the solvent; these are compared with the negative values for ΔG°t(i) for small cations.
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    The Medium Effect for Single Ionic Species
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (09), 1974) Parsons, Roger; Rubin, Barry T.
    The relation of the “ medium effect ” or “ solvent activity coefficient ” to the directly measurable real free energy of transfer is discussed. Measurements of the latter quantity for solutions in aqueous solvents containing methanol, ethanol, dioxan, acetone, ethylene glycol, formamide or dimethyl sulphoxide are reported and discussed. The surface composition of the solvent mixture is accessible and this information can be used to set reasonable limits on the possible value of the “ medium effect ”. Thus it can be shown that some assignments of single ion medium effects based on oversimplified models of solvation are inadequate. The assignment based on the neglect of liquid junction potentials between solvents is often surprisingly good.
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    Ionic solvation in water + Co-solvent mixtures: Part 2.—Free energies of transfer of single ions from water into mixtures of water with acetone, isopropanol, glycerol or methanol
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (1-6), 1974) Cecil F. Wells
    The method used previously to calculate the free energy of transfer ΔG°t of the solvated proton from water into methanol + water mixtures is applied to mixtures of water with acetone, isopropanol or glycerol. ΔG°t(HCl) for these mixtures has been calculated from values for the standard electrode potentials for appropriate cells, and ΔG°t(Cl–) obtained using the values for ΔG°t(H+). ΔG°t for some silver salts into acetone + water are calculated from solubility products. These ΔG°t and other published ΔG°t(MX) for acetone + water and methanol + water are separated into ΔG°t(M+) and ΔG°t(X–). Values for the ionic product of water in methanol + water are used to calculate ΔG°t(OH–), and values for ΔG°t(NH4+)–ΔG°t(NH3) in methanol + water are also calculated. These ΔG°t values are compared with previous values in methanol + water and the differences between solvent mixtures discussed in terms of solvent structure and ionic solvation.
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    H2O-D20 Solvent Isotope Effects in Adiabatic Compressibility and Volume of Electrolytes and Non-electrolytes: Relation to Specificities of Ionic Solvation
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (1-6), 1974) Mathieson, J. G.; Conway, B. E.
    Adiabatic compressibilities and molar volumes of a number of simple inorganic salts and tetraalkylammonium salts have been measured in H2O and D2O. The infinite dilution values, ϕ°K,S, have been obtained by extrapolations based on results determined down to 0.001–0.002 mol kg–1, i.e., towards the Debye–Hückel limiting law region. With these ϕ°K,S values, hydration effects determining the solvent isotope difference of ϕ°K,S values in D2O and H2O are discussed in terms of electrostriction and differences of local rigidity or relaxation characteristics of the solvent lattice. The solvent isotope effects in ϕ°K,S are related to accessibility of the N+ centre in the organic ions investigated. Comparison with the isotope effects in the infinite dilution partial molal volumes indicate that the series of salts investigated can be classified into three groups according to the hydration behaviour of the cations. The behaviour of salts is compared with that of some neutral molecules, HOD and also some D-labelled acetic acids for which a secondary isotope effect is investigated.
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    Ionic Solvation in Methanol+Water Mixtures: Free Energies of Transfer from Water
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (5), 1973) Wells, Cecil F.
    The free energy of transfer ΔG°t(H+) of the solvated proton from water to methanol + water mixtures up to 50 % w/w methanol is considered as the sum of two processes, the transfer of a tetrahedral aqua-proton from water into the mixture using the Born expression and the subsequent replacement of an H2O molecule in the tetrahedron by a methanol molecule according to the equilibrium, H+(H2O)4solv+ CH3OHsolv⇌ H+(CH3OH)(H2O)3solv+ water. These values for ΔG°t(H+) are subsequently used to derive values for ΔG°t(halide ion) from the ΔG°t for the appropriate hydrogen halides, and ΔG°t(Cl–) then used to produce values of ΔG°t for other cations from ΔG°t for simple salts. These values for ΔG°t for the single ions are discussed with respect to solvation of ions by H2O and CH3OH molecules and structural effects in the bulk solvent.