ENTHALPY OF DIMERIZATION OF BENZENE IN WATER

We have used precise-flow and titration microcalorimetry to measure enthalpy changes associated with the dilution of aqueous benzene solutions. Such direct measurements were undertaken for comparison with a thermodynamic characterization of the system reported by another group using vapor-pressure measurements of benzene above aqueous solutions. All studies so far indicate that the observed effects can be explained by a dimerization of the benzene molecules, so that the system may be a basic one for study of hydrophotic association. The extent of dimerization occurs to such a small extent that the calorimetry experiments alone it was not possible to resolve the individual thermodynamic parameters K(dim) and DELTA H(dim) from the product of these two quantities.