This paper reports the results of studying on the vapor liquid equilibrium for the systems containing iodide. Based on the data of a series of binary systems and a ternary system determined by ourselves

we studied the following two problems

(a )Among the four variables

temperature

pressure

liquid and vapor compositions

we were able to predict anyone of them from the other three by use of thermodynamic method. This method was also proved to be helpful to test the thermodynamic consistancy of the experimental data. (b) We attempted to correlated these binary data and predict the properties of multicomponent systems. Our results indicated that although aqueous hydrogen iodide is a strong electrolytic solution

by use of NRTL equation and expanding its parameters into polynomial series of temperature

it was able to predict multicomponent equilibrium from binary data.