Browsing by Author "Lilley, Terence H."

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Aqueous solutions containing amino acids and peptides. Part 5.—Gibbs free energy of interaction of glycine with some alkali metal chlorides at 298.15 K
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (09-12), 1978) Kelley, Barry P.; Lilley, Terence H.
Cells with transference have been used to investigate the free energy of interaction of glycine with LiCl, NaCl and CsCl in aqueous solutions at 298.15 K. The experimental data were analysed to give the Lewis–Randall free energy coefficients which represent pairwise interactions between the salt ions and the amino acid. The Lewis–Randall coefficients were transformed to the McMillan–Mayer scale and these were then deconvoluted in an approximate manner to give the contributions arising from excluded volume (hard-sphere), electrostatic (Kirkwood) and solvent reorganisation effects. The excluded volume and solvent reorganisation contributions are found to be approximately equal in magnitude but opposite in sign, so that the frequently used Kirkwood electrostatic model represents the nett interactions well.
Aqueous solutions containing amino acids and peptides. Part 8.—Gibbs free energy of interaction of some α,ω-amino acids with sodium chloride at 298.15 K
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (09-12), 1978) Kelley, Barry P.; Lilley, Terence H.
Cells with transference have been used to obtain information on the free energy of interaction between sodium chloride and the amino acids β-alanine, γ-aminobutyric acid and Îµ-aminocaproic acid. The results obtained are compared with those obtained for some α-amino acids. It is shown that, whereas with the α-acids there is little change in the pairwise interaction parameter as the hydrocarbon side chain is extended, for the α,ω-acids the interaction with the ions of the salt becomes increasingly attractive as the homologous series is ascended.
Nuclear Magnetic Resonance Studies of Preferential Solvation: Part 1.—Hydrogen Peroxide + Water
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (5), 1973) Covington, Arthur K.; Lilley, Terence H.; Newman, Kenneth E.; Porthouse, Geoffrey A.
Studies of the alkali metal (7Li, 23Na, 87Rb, 133Cs) and halide (19F, 35Cl) resonance chemical shifts have been made in H2O2+ H2O solvent mixtures up to 85 % w/w peroxide with the addition of 10–3 mol kg–1 ethylenediaminetetra-acetic acid (EDTA) to complex transition metal ion impurities. When the chemical shifts were dependent on salt concentration, results were extrapolated to zero salt concentration. The variation of these infinite dilution shifts with peroxide mole fraction shows Rb+, Cs+ and F– to be preferentially solvated by peroxide and Li+ preferentially solvated by water. These conclusions can be put on a quantitative basis by assuming that the solvation changes can be represented by a series of n competitive equilibria, where n is the solvation number, assumed to be the same for both water and peroxide. The free energy of preferential solvation has been determined where ΔG⊖ps=–RT ln K and K is the equilibrium constant for the overall process X(H2O)n+ H2O2⇌ X(H2O2)n+nH2O. K is related to the equilibrium constant for the ith step by K=[iKi/(n+ 1 –i)]n. The relation of ΔG⊖ps to the free energy of transfer of a neutral combination of ions from one solvent to another, ΔG⊖t, is discussed.
Rapidly Converging Activity Expansions for Representing the Thermodynamic Properties of Fluid Systems: Gases, Non-electrolyte Solutions, Weak and Strong Electrolyte Solutions
(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (05), 1978) Wood, Robert H.; Lilley, Terence H.; Thompson, Peter T.
For dilute gases and non-electrolyte solutions in the McMillan–Mayer standard state, an activity expansion due to Mayer has great advantages over the normal concentration expansion (virial equation) for strongly associating species. For weakly interacting systems, both approaches are suitable. The activity expansion eliminates the need to differentiate between strong “chemical” interactions and weak “physical” interactions since the same equation is used in each situation. The equation has been modified to represent electrolyte solutions in the McMillan–Mayer standard state by requiring that it be consistent with the Debye–Hückel and higher order limiting laws for strong electrolytes and that it be equivalent to a chemical association model for weak electrolytes. The result is a compact equation which contains no arbitrary ion-size parameters and which does not require the classification of an electrolyte as strong or weak. For 2:2 electrolytes, the equation gives a very good fit to the anomalous low concentration region. For practical thermodynamic calculations, similar equations for molal activity coefficients are proposed; good fits of the data are obtained.