Based on the liquid model of statistical thermodynamics and the concept of local composition

the equations of Gibbs free energy and activity coefficient of liquid mixtures are derived. The equation of viscosity of liquid mixtures is obtained by combining the model with the theory of reaction rate. Then the correlation between viscosity and vapor-liquid equilibrium is obtained. Predictions of vapor-liquid equilibrium data of 14 binary systems from viscosities of liquid mixtures are given in this paper. The predicted results agree with experimental data. It is shown that the equations and the prediction method are of good applicability and reliability.