Semiempirical Model of the Vapor-Liquid Phase Behavior of the Hydrogen Chloride-Water System

A simple, accurate, and widely applicable semiempirical vapor-liquid equilibrium model is developed for the HCl-water system. The model is based on the modified Raoultʹs law, adjusted to include a function known as the "pseudo-vapor pressure." The resulting set of equations relate total pressure, liquid bulk (nonionized) composition, vapor composition, and temperature. The parameters were fit to a wide range of data available in the literature (-10 to 200 (degree)C, 0.00268-66.1 atm, and 2-54.9 wt % HCl) that includes the supercritical region. The final equations are demonstrated to allow straightforward calculation of azeotropes and dew points.