Aa. Povodyrev et al., VAPOR-LIQUID-EQUILIBRIA, SCALING, AND CROSSOVER IN AQUEOUS-SOLUTIONS OF SODIUM-CHLORIDE NEAR THE CRITICAL LINE, Physica. A, 244(1-4), 1997, pp. 298-328
We have developed a crossover scaling model for describing the thermod
ynamic properties of near-critical binary fluids. We have validated th
is model for the vapor-liquid equilibrium properties of mixtures of me
thane and ethane. We then apply the model to a most intriguing binary
fluid, namely aqueous solutions of sodium chloride, so as to describe
densities and concentrations at vapor-liquid equilibrium and isochoric
specific heat capacities in the one-phase region. The description sho
ws crossover from asymptotic Ising-like critical behavior to classical
(mean-field) behavior. As the salt concentration increases, the regio
n of Ising behavior decreases, although pure classical behavior is nev
er attained, We suggest that processes of association/dissociation may
be responsible for the failure of the model to describe compositions
of the vapor phase of the solutions at very low concentrations.