Thermodynamic properties of binary systems containing hexafluorobenzene. Part 4.—Excess Gibbs free energies of the three systems hexafluorobenzene + benzene, touene, and p-xylene
The excess Gibbs free energy of the three binary systems hexafluorobenzene + benzene, + toluene, and + p-xylene have been measured in the temperature range 30–70° using a static method. The hexafluorobenzene + benzene system appears to be unique among solutions of non-electrolytes in that it forms a double azeotrope at all the experimental temperatures. All three systems are believed to form equimolar, intermolecular complexes in the liquid, as well as in the solid, states. The experimental free energy data have been analyzed to yield values of the equilibrium constants and enthalpies of formation for the complexing reaction.