Limiting partial molar excess heat capacities and volumes of selected organic compounds in water at 25 degrees C

Well-known Picker flow microcalorimeters for the differential measurements of volumetric heat capacities have been employed in conjunction with vibrat ing tube densimeters to determine the molar heat capacity, volume, and the apparent properties in dilute aqueous solutions for 17 organic solutes of m oderate hydrophobicity. The dependence on concentration of the apparent pro perties allowed the limiting partial molar quantities at infinite dilution to be extrapolated and the limiting partial molar excess quantities to be e valuated. Comparison with available literature data shows good agreement. T he application of group contribution rules to the limiting partial properti es has been tested using the original method and parameters proposed by Cab ani et al. The predicted values of the partial molar volumes are in fair ag reement with the present data except for some less common solutes. With par tial molar heat capacities, the agreement is less satisfactory. To improve the performance of the method, missing parameters for some types of monofun ctional and bifunctional molecules have been evaluated.