Critical parameters and saturated density of trifluoroiodomethane (CF3I)

The vapor-liquid coexistence curve of trifluoroiodomethane (CF3I) was measu red by visual observation of the meniscus disappearance in an optical cell. Thirty-two saturated density data points were obtained along the vapor-liq uid coexistence curve between 384.5 and 2024.9 kg . m(-3) in the temperatur e range from 301.02 K to the critical temperature. The experimental uncerta inties in temperature and density were estimated to be within +/-10 mK and +/-0.5%, respectively. Measurements near the critical point were used to de termine the critical temperature T-c = 396.44 +/- 0.01 K and the critical d ensity rho(c) = 868 +/- 3 kg . m(-3) for trifluoroiodomethane (CF3I) on the basis of the meniscus disappearing level as well as the intensity of the c ritical opalescence. The critical pressure p(c) = 3.953 +/- 0.005 MPa was e xtrapolated from the existing vapor pressure equation proposed previously ( Duan, Y. Y.; Zhu, M. S.; Han, L. Z. Fluid Phase Equilib. 1996, 121, 227-234 ) using the present T-c value. The critical exponent, beta, was also determ ined, and correlations of the saturated liquid and saturated vapor densitie s of CF3I were developed.