Critical Parameters and Saturated Density of Trifluoroiodomethane (CF_3I)

摘要

The vapor-liquid coexistence curve of trifluoroiodomthane (CF_3I) 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 approx 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 T_c=396.44 (+-)0.01 K and the critical density #rho#_c=868(+-)3 kg centre dot m~(-3) for trifluoroiodomethane (CCF_3I) on the basis of the mensicus disappearing level as well as the intensity of the critical opalescence. The critical pressure p_c=3.953(+-)0.005 MPa was extrapolted from the existing vapor pressure equation proposed previously (Duan, UY.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 determined, and correlations of the saturated liquid and saturated vapor densities of CF_3I were developed.