ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 21, Number 6
JKCSEZ 21(6)
December 20, 1977 

Significant structure theory was applied to some liquid mixture systems ranging from simple monatomic molecule systems to polyatomic molecule systems, and the activity coefficients γ of the liquid mixture systems were calculated over whole mole fractions using the following thermodynamic relation RTln γi = (∂AE / ∂Ni)T,V,Nj where AE represents the excess Helmholtz free energy, and Ni is the number of molecules of component i. The activity coefficients of the solutions such as monatomic molecule systems (Ar-Kr, Kr-Xe) and diatomic molecule systems (Ar-O2, N2-CO) and CH4-Kr systems whose components have similar shapes for intermolecular potential curves were calculated successfully only with the δEs, correction parameter for energy Es, for mixture systems. For other systems such as Ar-N2, O2-N2 and CH4-C3H8 whose components have dissimilar intermolecular potential curve shapes an additional correction parameters δV and even one more parameter δn were necessary [see Eqs.(10)∼(12)].