Critical parameters for 1,1,1-trifluoroethane (R-143a)

Measurements of the vapor-liquid coexistence curve near the critical point were carried out for 1,1,1-trifluoroethane (R-143a) in the reduced temperature range of 0.97 < T/T_c < 1 and in the reduced density range of 0.45 < ρ/ρ_c < 1.53. Taking into consideration of the disappearing level of the meniscus as well as the intensity of the critical opalescence, the critical temperature T_c and critical density ρ_c were determined. With respect to the critical pressure P_c, we calculated the value from the new vapor-pressure equation made by ourselves in order to represent the behavior of vapor-pressures near the critical point. The critical parameters determined in this paper are T_c = 345.88 + δ_T K, δ_T = 0.00±0.01 K, ρ_c = 431 ± 3 kg m^-3, and P_c = 3764 + 78.73δ_T ± 5 kPa. In addition, the critical exponent β along the coexistence curve was also discussed.