The contour of excess molar enthalpy at a mole fraction of benzene x = 0.548 on the p-T plane in liquid state and near the critical points for the (benzene + cyclohexane) mixture

Abstract

Abstract The excess molar enthalpy HEm(x = 0.548) of the {x benzene + (1 − x) cyclohexane} mixture was measured near the vapour pressure curve of benzene, and was measured in the intermediate region between the liquid state and the state near the critical points. The contour of HEm(x = 0.548) was created on the p-T plane over a wide range of temperature and pressure including near the critical points. A valley was observed for the HEm(T, p, x = 0.548) surface in the intermediate region between the liquid state and the state near the critical points. The HEm(x = 0.548) smoothly decreased on the high-temperature side of the valley as temperature and pressure increased, and dramatically increased in this region as the temperature and pressure approached the critical points. Near these critical points, the HEm(T, p, x = 0.548) surface had two ridges, which extended the vapour pressure curves of benzene and cyclohexane. Finally, it was observed that near the critical point of benzene, HEm(x = 0.548) reached a local maximum at a temperature and pressure slightly less than the critical point of benzene.