THERMODYNAMIC PROPERTIES OF 7 GASEOUS HALOGENATED HYDROCARBONS FROM ACOUSTIC MEASUREMENTS - CHCLFCF3, CHF2CF3, CF3CH3, CHF2CH3, CF3CHFCHF2,CF3CH2CF3, AND CHF2CF2CH2F

Measurements of the speed of sound in seven halogenated hydrocarbons a re presented. The compounds in this study are l-chloro-l,2,2,2-tetrafl uoroethane (CHClFCF3, or HCFC-124), pentafluoroethane (CHF2CF3 or HFC- 125), 1,1,1-trifluoroethane (CF,CH, or HFC-143a), 1,1-difluoroethane ( CHF2CH3, or HFC-152a), 1,1,1,2,3,3-hexafluoropropane (CF3CHFCHF2 or HF C-236ea), 1,1,1,3,3,3-hexafluoropropane (CF3CH2CF3 or HFC-236fa), and 1,1,2,2,3-pentafluoropropane (CHF2CF2CH2F or HFC-245ca). The measureme nts were performed with a cylindrical resonator at temperatures betwee n 240 and 400 K and at pressures up to 1.0 MPa. Ideal-gas heat capacit ies and acoustic virial coefficients were directly deduced from the da ta. The ideal-gas heat capacity of HFC-125 from this work differs from spectroscopic calculations by less than 0.2% over the measurement ran ge. The coefficients for virial equations of state were obtained from the acoustic data and hard-core square-well intermolecular potentials. Gas densities that were calculated from the virial equations of state for HCFC-124 and HFC-125 differ from independent density measurements by at most 0.15%, for the ranges of temperature and pressure over whi ch both acoustic and Burnett data exist. The uncertainties in the deri ved properties for the other five compounds are comparable to those fo r HCFC-124 and HFC-125.