Thermal and Volumetric Properties of Some C5 and C6 Alkanones at Infinite Dilution in Water

Precise measurements of excess enthalpies and densities of highly dilute aqueous solutions of five C5–C6 alkanones (namely 2-pentanone, 3-pentanone, 3-methyl-2-butanone, 2-hexanone, and 4-methyl-2-pentanone) were carried out using tandem flow mixing calorimetry and vibrating-tube densimetry. The experimental data obtained in the temperature range from 288.15 to 318.15 K were utilized for the evaluation of limiting partial molar excess enthalpies, partial molar volumes, and partial molar excess volumes of the alkanones in water. Within the temperature range studied, these infinite dilution properties were found to exhibit linear trends. As inferred from respective linear fits, partial molar excess heat capacities, partial molar expansions, and excess partial molar expansions were obtained with a good accuracy. Moreover, hydration enthalpies and heat capacities of the alkanones studied were evaluated, too. The thermodynamic behavior of the alkanone solutes was discussed in terms of molecular interactions and shown to be closely correlated with that for equi-structured alkanol solutes.