Density, Viscosity, Refractive Index, Isobaric Specific Heat Capacity, Ultrasonic Velocity, Molar Volume, Isentropic Compressibility, Isothermal Compressibility, and Heat Capacity Ratio for Binary Mixtures of the Organic Liquids Ethylbenzene, Ethylcyclohexane, Pentylbenzene, and Pentylcyclohexane at 298.15 K and 0.1 MPa

Ethylbenzene, ethylcyclohexane, pentylbenzene, and pentylcyclohexane, both pure and binary mixtures, were studied to ascertain the effects of the molecular structure and the physical properties of the pure components on resultant properties of the binary mixtures. Density, viscosity, refractive index, isobaric specific heat capacity, and ultrasonic velocity were measured for the pure materials and for the six possible binary mixtures of the four hydrocarbons. Molar volume, isentropic compressibility, isothermal compressibility, and heat capacity ratio were calculated from the measured quantities. Deviations from ideality were determined as either excess or increment values for each physical property for each mixture. The sign and magnitude of the deviation values varied depending on the property and the mixture. The isothermal compressibility was successfully calculated from the isentropic compressibility using a well-known thermodynamic relationship. The isentropic compressibility was found to be almost a linear function of mixture composition and the difference between the isothermal and isentropic compressibilities was also found to be a smooth function of mixture composition. The difference only varies between 0.15 and 0.22 GPa–1 depending on the specific binary mixture. The heat capacity ratio was found to be a smooth, almost linear function of composition.