Thermodynamic properties of trifluoroiodomethane (CF3I)

Studies of the thermodynamic properties of trifluoroiodomethane (CF3I) are presented in this paper. The vapor-liquid coexistence curve of CF3I was mea sured by visual observation of the meniscus. The critical temperature and t he critical density of CF3I were determined by considering not only thy lev el where the meniscus disappeared but also the intensity of the critical op alescence. The correlation of the saturated density in the critical region was developed, and the exponent of the power law beta was determined. Corre lations of the saturated vapor and liquid densities and the enthalpy of vap orization for CF3I were also developed. The vapor pressure of CF3I was meas ured at temperatures ranging from below the normal boiling point to the cri tical point, and a vapor pressure equation for CF3I was developed, from whi ch the normal boiling point of CF3I was determined. The gaseous PVT propert ies of CF3I were measured with a Burnett/isochoric method, and a gaseous eq uation of state for CF3I was developed. The speed of sound of gaseous CF3I was measured with a cylindrical, variable-path acoustic interferometer oper ating at 156.252 kHz. and the ideal-gas heat capacity and second acoustic v irial coefficient were calculated. A correlation of the secund virial coeff icient for CF3I was obtained by a semiempirical method using the square-wel l potential for the intermolecular force and was compared with the result b ased on PVT measurements. The surface tension of CF3I was measured with a d ifferential capillary rise method (DCRM), and the temperature dependence of the results was successfully represented to within +/- 0.13 mN(.)m(-1) usi ng a van der Waals correlation.