The experimental physical solubility data are correlated by a three-parameter model based on the Margules equation. In addition, the total solubilities in which chemical reaction is taken into account are measured by the synthetic method.
2, the activity coefficient [[gamma].sub.2] is the function of mole fraction [x.sub.2], which can be described by Margules equation:
where [A.sub.21] and [A.sub.12] are the coupling parameters of Margules equation and [A.sub.21] is related to the infinite-dilution activity coefficient ([[gamma].sub.2.sup.[infinity]]) of solute by the expression as