Asymmetric criticality in weakly compressible liquid mixtures

Abstract

The thermodynamics of asymmetric liquid-liquid criticality is updated by incorporating pressure effects into the complete-scaling formulation earlier developed for incompressible liquid mixtures [C. A. Cerdeirina et al., Chem. Phys. Lett. 424, 414 (2006); J. T. Wang et al., Phys. Rev. E 77, 031127 (2008)]. Specifically, we show that pressure mixing enters into weakly compressible liquid mixtures as a consequence of the pressure dependence of the critical parameters. The theory is used to analyze experimental coexistence-curve data in the mole fraction-temperature, density-temperature, and partial density-temperature planes for a large number of binary liquid mixtures. It is shown how the asymmetry coefficients in the scaling fields are related to the difference in molecular volumes of the two liquid components. The work resolves the question of the so-called "best order parameter" discussed in the literature during the past decades.

Critical behavior of binary mixture of {x C6H5CN + (1 −x) CH3(CH2)12CH3}: Measurements of coexistence curves, turbidity, and heat capacity

“…The presence of term t 2b was a direct consequence of complete scaling theory [22][23][24][25], while it was thought to be a contribution from a wrong choice for the order parameters [1,26] in the past. It is almost impossible to simultaneously obtain the coefficients D 1 , D 2 , and D 3 by fitting the experimental data of the coexistence curves to equation (11); however, the diameter q d may be fitted to the form:…”

Critical Locus of Aqueous Solutions of Sodium Chloride Revisited

“…This improved principle of scaling behavior is now referred to as complete scaling. And indeed, complete scaling has turned out to give a proper account of the observed asymmetric critical phase behavior in fluids [19][20][21][22][23]. In this article, we shall show that complete scaling implies an analytic relationship between the critical pressure and the critical temperature, even though P c and T c individually exhibit a non-analytic dependence on the concentration as predicted by Kim and Fisher [11].…”

“…That is, the anomalous singular critical behavior of various thermodynamic properties is solely caused by the non-analytic dependence of h 3 on h 1 and h 2 and not by any non-analyticities in the dependence of the scaling fields on the physical fields. According to the principle of complete scaling for binary solutions, the scaling fields will be analytic functions of four physical fields which can be identified with the temperature T , the pressure P , the chemical potential μ 1 of the solvent, and the chemical-potential difference μ 21 = μ 2 − μ 1 , where μ 2 is the chemical potential of the solute [20][21][22]. To satisfy Eq.…”

Isomorphic Viscosity Equation of State for Binary Fluid Mixtures

“…(5) are both functions of P r and T r as: 25 (12) (13) and the functional form of τ (T r ,P r ) and ϕ (T r ,P r ) were adopted as follow: 25 (14) (15) in which Q i were generalized in terms of acentric factor ω and molecular weight M in the following forms: 25 Behnejad Thermodynamic properties were made dimensionless using the critical parameters: (19) In addition, defining: (20) the SRK viscosity equation can be re-expressed in terms of dimensionless variables: where definitions of r, b', τ(T r ,P r ) and ϕ(T r ,P r ) are analogous to Eqs. (12)-(15).…”

“…This approach was developed through relating the two relevant scaling fields to the linear combinations of three physical field variables -the temperature, pressure and chemical potentials of the two components. [11][12][13][14][15][16] Moreover, based on an asymmetric EoS, the crossover equation of state was considered to extend its range of applicability to a wider region around the critical point for the single and two-component fluids. [17][18][19][20][21] In the vicinity of critical point, the viscosity of fluid is one of the thermo-physical properties which exhibits an increasing anomaly.…”