Enthalpies, heat capacities, and volumes of transfer of the tetrabutylammonium ion from water to aqueous mixed solvents from the point of view of the scaled-particle theory

The enthalpies, heat capacities, and volumes of transfer of the tetrabutylammonium ion from water to urea–water, tert-butyl alcohol–water, and sodium chloride–water mixtures have been calculated at 25 °C using the scaled-particle theory. In general, the signs, magnitudes, and overall trends in the cosolvent concentration dependence of the properties are predicted from the cavity contributions only. These calculations are found to be very sensitive to the diameters chosen for the various species.For these calculations it was necessary to measure with a dilatometer the coefficients of thermal expansion of tert-butyl alcohol–water mixtures as a function of concentration and temperature.