Ultrasonic speeds in dense liquid and bubble-point pressures for binary mixtures of pentafluoroethane and 1,1,1-trifluoroethane

The ultrasonic speeds in the compressed liquid and bubble-point pressures for binary mixtures of pentafluoroethane, CHF 2 CF 3 , and 1,1,1-trifluoroethane, CF3CH3, were measured by a sing-around technique operated at a frequency of I MHz. The results cover the wide temperature range from 243.15 K to 333.15 K and from near the saturation line to about 30 MPa. The uncertainties in the present values are estimated, respectively, to be less than ±0.2% for the ultrasonic speed and ±20 kPa for the bubble-point pressure, except for those at high temperature. From these data, the ultrasonic speed for the saturated liquid was estimated by extrapolation to the bubble-point pressure. The temperature, pressure, and composition dependences of ultrasonic speeds are discussed with reference to those for binary mixtures reported previously.