Temperature correlation of partial molar volumes of aqueous hydrocarbons at infinite dilution: test of equations

A data set of partial molar volumes at infinite dilution was established for benzene(aq), toluene(aq), cyclohexane(aq) and hexane(aq) at temperatures up to 623 K and at pressures to 30 MPa. Data from new densimetric measurements at high temperatures were combined with literature data near room temperature and with estimates based on similarity in the behaviour of hydrocarbon solutes. Three types of correlation equations which describe the partial molar volume of a solute at infinite dilution as a function of state parameters were tested: the model of Helgeson–Kirkham–Flowers using dielectric properties of water, semiempirical equations using the compressibility of water and equations based on the fluctuation solution theory. One equation was selected as representative for expressing the pressure dependence of the Henryʹs constant.