Thermodynamics of liquid mixtures of nitrous oxide and xenon

Abstract

The total vapour pressure, excess volume and excess enthalpy of the system nitrous oxide + xenon have been measured as a function of composition; the vapour pressure and excess volume measurements are at 182.32 K (the triple-point of N₂O) and those for the excess enthalpy are at 184.05 K. The vapour pressure results have been used to estimate the excess Gibbs energy. The mixture exhibits a positive azeotrope at a N₂O mole fraction of ≈ 0.08. The experimental results are compared with values calculated from perturbation theory for non-spherical molecules, using an intermolecular potential model that includes dipolar and quadrupolar electrostatic terms. Agreement is good for the properties of both the pure fluids and the mixture and is a substantial improvement over theories that neglect the acentric nature of the intermolecular forces.