Thermo-Acoustic Properties of (Ethanol plus n-Heptane) Binary Mixtures from 293.35 to 433.89 K and up to 5.0 MPa

The experimental speeds of sound for the binary system of ethanol (1) + n-heptane (2) with the mole fractions of ethanol being (0.100, 0.300, 0.500, 0.700, and 0.900) were measured by Rayleigh-Brillouin light scattering spectroscopy at temperatures from 293.35 to 433.89 K along three isobaric lines from 0.1 to 5.0 MPa. The expanded relative uncertainty for the reported speed of sound is estimated to be 1.6% with the level of confidence of 0.95 (coverage factor k = 2). The experimental data were correlated as a function of temperature and pressure, yielding absolute average percentage deviations of 0.34, 0.20, 0.38, 0.28, and 0.29% for the mole fractions of ethanol being 0.100, 0.300, 0.500, 0.700, and 0.900, respectively. Within the temperature limits of 298.15-318.15 K, the derived thermo-acoustic properties for the binary system of ethanol (1) + n-heptane (2), including the density, the specific isobaric heat capacity, the isentropic compressibility, the isobaric thermal expansivity, the isothermal compressibility, the specific heat ratio, the internal pressure and the free volume at pressures up to 5.0 MPa, and the intermolecular free length under atmospheric pressure were calculated and analyzed.