Thermodynamic properties of cyclohexane–methanol liquid mixture from shear viscosity measurements

The binary liquid mixture cyclohexane–methanol has an upper critical point at a mass composition of 27.5% of methanol and critical temperature Tc = 319.608 ± 0.234 K. The shear viscosity and density of this system have been carried out as a function of temperature, under atmospheric pressure, over the composition range along the coexistence curve above the transition temperature. From these experimental data values, various thermodynamic parameters, namely, Gibbs energy (ΔG), enthalpy and entropy activation parameters ΔH and ΔS, the excess molar volume (VE), excess Gibbs energy (ΔGE), viscosity deviations (Δη) and the activation energy (Eav) have been calculated and fitted to Redlish–Kister equation. Furthermore, in the one-phase region just above Tc of the critical binary fluid, the viscosity measurements yield to an enhancement as expected for Ising criticality with a crossover to regular behavior. The regular background is obtained by interpolation from the measurements at non-critical concentrations. The viscosity has been also correlated with the equation of Grunberg–Nissan, Hind et al., Katti–Chaudhri, Heric–Brewer, McAllister, Auslander and Acree–Jouyban.