Liquid mixtures involving cyclic molecules. 2: Xenon plus cyclobutane

The total vapor pressure of liquid mixtures of xenon and cyclobutane has be en measured at 182.34 K (the triple point of dinitrogen oxide) and at 195.4 9 K (the triple point of ammonia), as a function of composition. The mixtur es show small positive deviations from Raoult's law at both temperatures. T he liquid densities were also measured at 182.34 K. Both the excess molar G ibbs energy (G(m)(E)) and the excess molar volume (V-m(E)) were calculated from the experimental data. For the equimolar mixture G(m)(E) = 9.9 J mol(- 1) at 182.34 K, G(m)(E) = 24.0 J mol(-1) at 195.49 K, and V-m(E) = -1.077 c m(3) mol-1 at 182.34 K. The excess molar enthalpy (H-m(E)) was estimated fr om the temperature dependence of G(m)(E) and found to be -185 J mol(-1). Th e results were interpreted by using the statistical association fluid theor y and compared with those for the linear analogue system (xenon + n-butane) .