Derivation and consistency of the partial functions of a ternary system involving interaction coefficients

Abstract

Abstract Margules equations are used to express the thermodynamics of a ternary system containing one solvent and two solutes in the vicinity of solvent, in terms of first order interaction coefficients of binary and ternary systems. Considering just the first order Margules coefficients, the resultant excess Gibbs energy function was convergent and the derived logarithmic activity coefficients of solvent and solutes were thermodynamically consistent. In the present study Margules equations are modified to get consistent equations. Partial functions of a ternary system are deduced using these modified equations via the excess Gibbs energy function. Derived partial functions are thermodynamically consistent and also deduced results are the same as those obtained using Maclaurin infinite series. Using the activity coefficient expressions of solvent and solutes, the activity coefficients of solvent and solute are calculated in Ni– Cr–Fe and Fe–Ti –C ternary systems, which are in excellent agreement with the experimental data.