MOLAR HEAT-CAPACITY OF BINARY-LIQUID MIXTURES - 1,2-DICHLOROETHANE + CYCLOHEXANE AND 1,2-DICHLOROETHANE + METHYLCYCLOHEXANE

The molar heat capacity at constant pressure, CP, of the two binary liquid mixtures 1,2-dichloroethane + cyclohexane and 1,2-dichloroethane + methylcyclohexane were determined at 298.15 K from measurements of the volumetric heat capacity, CP/V, in a Picker flow microcalorimeter (V is the molar volume). For the molar excess heat capacity, CPE, the imprecision of the adopted stepwise procedure is characterized by a standard deviation of about ± 0.05 J K-1 mole-1, which amounts to ca. 3% of CPE. Literature data on ultrasonic velocities, on molar volumes, and on coefficients of thermal expansion were used to calculate the molar heat capacity at constant volume, Cv, and the isothermal compressibility, βT, of the pure substances, as well as the corresponding excess quantities CVE and (VβT)E of the binary mixture 1,2-dichloroethane + cyclohexane. A preliminary discussion of our results in terms of external and internal rotational behavior (trans-gauche equilibrium of 1,2-dichloroethane) is presented. © 1979.