The vapor pressure, infrared spectrum, and thermodynamic properties of ZrF4(g)

Article abstract of DOI:10.1006/jcht.1994.1033

The vibrational spectrum of ZrF4 in the gas phase was measured by high-temperature infrared spectroscopy.The spectrum showed two strong bands which were assigned to the asymmetric stretching wavenumber <*>₃ and the asymmetric bending wavenumber <*>₄.From a correlation of the established i.r.-inactive wavenumbers in other MX₄ molecules with the i.r.-active values, the two i.r.-inactive modes in ZrF₄ were estimated with an expected accuracy of about +/-15 cm^-1.In addition, the vapor pressure of ZrF4(c) was measured in the range 700 K to 850 K by the torsion-effusion technique, yielding for the equilibrium pressure p_e: , where p^o=101.325 kPa.The entropy of ZrF4(g), derived from the second-law entropy of vaporization and the known entropy of the solid, is in close accord with the corresponding statistical value calculated from the vibrational wavenumbers and the reported structural parameters for tetrahedral ZrF4, showing that the results are internally consistent.Enthalpies of sublimation and thermodynamic properties of ZrF4(g) are reported.