Vapor-Liquid Coexistence Curve and the Critical Parameters of 1-Chloro-1,1-difluoroethane (HCFC-142b)

Vapor-liquid coexistence curve near the critical point of 1-chloro-1,1-dlfluoroethane (HCFC-142b) was measured by a visual observation of the meniscus In an optical cell. Saturation densities Including 13 saturated-vapor and 18 saturated-liquid densities were obtained In the range of temperature from 354 K to the critical temperature, corresponding to the density range from 181 to 947 kg/m³. The experimental errors In temperature and density were estimated to be within ±10 mK and between ±0.09 and ±0.53%, respectively. Not only the level where the meniscus disappeared but also the Intensity of the critical opalescence were considered for the determination of the critical temperature and density as 410.29 ± 0.02 K and 446 ± 3 kg/m³, respectively. The critical exponent, β, was also determined to be 0.339 ± 0.002. A saturated-vapor/saturated-liquid density correlation was developed on the basis of the present measurements.