title: Molecular Thermodynamics of Methane Solvation in tert-Butanol-Water Mixtures.
abstract: We studied solvation structure and thermodynamics of methane in mixtures of tert-butanol and water using computer simulations. We show that for alcohol mole fractions below 20%, methane is preferentially solvated by hydrated alcohol clusters. Because methane expels water molecules from these clusters, a large endothermic solvent reorganization enthalpy occurs. This process is responsible for the experimentally observed maximum of the heat of methane solvation close to 5% alcohol in the mixture and contributes to a positive entropy change relative to solvation in pure water. Because the structural solvent reorganization enthalpy is enthalpy-entropy compensating, the methane solvation free energy is a smoothly varying function of the alcohol/water solution composition.
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
authors.forename: Maeng-Eun
authors.initials: ME
authors.lastname: Lee
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
authors.forename: Nico F A
authors.initials: NF
authors.lastname: Van der Vegt