Thermodynamic properties of seven gaseous halogenated hydrocarbons from acoustic measurements: CHClFCF3, CHF2 CF3, CF3 CH3, CHF2CH3, CF3CHFCHF2, CF3CH2CF3, and CHF2CF2CH2F

Measurements of the speed of sound in seven halogenated hydrocarbons are preseInted. The compounds in this study are l-chloro-l,2,2,2-tetralluoroethane (CHCIFCF 3 or HCFC-124), pentafluoroethane (CHF_,CF~ or HFC-1251, I,l,ltrifluoroethane (CF3CH3 or HFC-143a), I,l-difluoroethane (CHFzCH~ or HFC-152a), I,l,l,2,3,3-hexafluoropropane (CF3CHFCHF, or HFC-236ea), l,l,l,3,3.3-hexalluoropropane (CF3CH,CF 3 or HFC-236fa), and I,l,2,2,3- pentafluoropropane (CHF2CFzCH _, F or HFC-245ca). The measurements were performed with a cylindrical resonator at temperatures between 240 and 400 K and at pressures up to 1.0 MPa. Ideal-gas heat capacities and acoustic virial coefficients were directly deduced from the data. The ideal-gas heat capacity of HFC-125 from this work differs from spectroscopic calculations by less than 0.2% over the measurement range. The coeMcients for virial equations of state were obtained from the acoustic data and hard-core square-well iIntermolecular potentials. Gas densities that were calculated from the virial equations of state tbr HCFC-124 and HFC-125 differ from independent density measttrements by at most 0.15%, for the ranges of temperature and pressure over which both acot, stic and Burnett data exist. The uncertainties in the derived properties Ibr the other five compounds are comparable to those for HCFC-124 and HFC-125.