In this paper, we report new PVTx measurements for water + toluene binary mixtures at 11 near-critical and supercritical isotherms T ) 623, 627, 629, 631, 633, 643, 645, 647, 649, 651, and 673 K and pressures up to 39 MPa at a fixed concentration of x ) 0.0287 mole fraction of toluene. Using these PVTx data together with data obtained earlier by other authors, we developed a crossover Helmholtz free-energy model (CREOS) for pure toluene and dilute aqueous toluene solutions in a wide range of the parameters of state around the vapor-liquid critical points. In the temperature range 593 K e T e 680 K and density range 100 kg‚m -3 e F e 500 kg‚m -3 , the CREOS reproduces the PVT data for pure toluene with an average absolute deviation (AAD) of about 0.5%, the C P data with an AAD of about 1%, and the sound velocity data with an AAD of about 2.6%. In water + toluene mixtures, the CREOS yields an adequate description of all available experimental data in the region bounded by 0.35F c (x) e F e 1.65F c (x) and 0.98T c (x) e T e 1.15T c (x) at x e 0.04 mole fraction of toluene. The possibility of extrapolating the CREOS model to lower temperatures, 0.93T c e T eT c , and higher densities and concentrations, up to F ) 2F c and x ) 0.12, is also discussed.
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