Hexafluorobenzene and 1,3-difluorobenzene low-temperature calorimetric studies and chemical thermodynamic properties

• Published in: The Journal of chemical thermodynamics 1970, Vol.2 (6), p.867-880
• Main Authors: Messerly, J.F., Finke, H.L.
• Format: Article
• Language: English
• ISSN: 0021-9614; 1096-3626
• DOI: 10.1016/0021-9614(70)90030-3

The low-temperature thermal properties of hexafluorobenzene and 1,3-difluorobenzene were measured by adiabatic calorimetry from 13 to 342 K and 11 to 355 K, respectively. The properties measured were heat capacities of solid and liquid, enthalpies of fusion, triple point temperature, and purity, and, in addition, for 1,3-difluorobenzene, the enthalpy and temperature of a solid-solid transition. From these results the following chemical thermodynamic functions were calculated for the condensed phases at selected temperature: Gibbs energy function, enthalpy function, enthalpy, entropy, and heat capacity. For 1,3-difluorobenzene the entropies in the ideal gas state were calculated at several temperatures, a revised vibrational assignment was made from Raman and infrared frequencies reported in the literature, and the chemical thermodynamic functions in the ideal gas state were calculated from 0 to 1500 K. Values of the Gibbs energy of formation and logarithm of equilibrium constant of formation for 1,3-difluorobenzene were also computed for the range 0 to 1500 K.