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Author: search.filters.author.Stokes, Robin H.Subject: search.filters.subject.Thermodynamic

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    Thermodynamic Functions for the System Ethanol-F Cyclohexane from Vapour Pressures and Enthalpies of Mixing
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (09), 1977) Stokes, Robin H.; Adamson, Marion
    Activity coefficients for the system ethanol + cyclohexane at 45°C are obtained from vapour pressure measurements using a stepwise dilution apparatus. Enthalpies of mixing for the range xA= 0.1 to 0.99 (xa= mole fraction of ethanol) supplementing those reported previously for the range up to xA= 0.16, are obtained at seven temperatures by isothermal dilution calorimetry. Conversion of the activity coefficients to 6.7°C shows that the activity data obtained previously from freezing-point measurements were in error, owing to suspected solid solution formation.
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    Interpretation of the Thermodynamic, Spectroscopic and Dielectric Properties of Solutions of Ethanol in Cyclohexane in Terms of Association
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (07), 1977) Stokes, Robin H.
    A model is proposed to explain the thermodynamic, spectroscopic and dielectric properties of dilute solutions of ethanol in cyclohexane in terms of association into both open-chain and cyclic hydrogen bonded groups, with allowance for a Van der Waals interaction term. It proves necessary to specify: two standard enthalpies for formation of the H-bonds, h2=–21.2 kJ mol–1 for the dimer and h=–23.5 kJ mol–1 for all larger groups; three standard entropies of stepwise formation (for the dimer, trimer and all higher open-chain forms); and a standard entropy of formation from open-chain to cyclic groups, which are assumed to be present to a significant extent only for groups of more than four molecules. This model gives a quantitative reproduction of the activity coefficients, enthalpies of mixing and i.r. spectroscopic behaviour, and accounts for the initial decrease in the apparent dipole moment.