Critical Parameters and Saturated Density of Trifluoroiodomethane (CF3I)

The vapor−liquid coexistence curve of trifluoroiodomethane (CF3I) was measured by visual observation of the meniscus disappearance in an optical cell. Thirty-two saturated density data points were obtained along the vapor−liquid coexistence curve between 384.5 and 2024.9 kg·m-3 in the temperature range from 301.02 K to the critical temperature. The experimental uncertainties in temperature and density were estimated to be within ±10 mK and ±0.5%, respectively. Measurements near the critical point were used to determine the critical temperature Tc = 396.44 ± 0.01 K and the critical density ρc = 868 ± 3 kg·m-3 for trifluoroiodomethane (CF3I) on the basis of the meniscus disappearing level as well as the intensity of the critical opalescence. The critical pressure pc = 3.953 ± 0.005 MPa was extrapolated 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 Tc value. The critical exponent, β, was also determined, and correlations of the saturated liquid and saturated vapor densities of CF3I were developed.