Modelization of liquid associated binary mixtures: Application to liquid vapor equilibria of binary systems containing water, hydrazines and hydrazones

Abstract

Measurements of the equilibrium liquid and vapor compositions vs. temperatures at 1.0 atm total pressure for three nonideal binary liquid systems were used to obtain thermodynamic parameters for a chemical association model of such systems. The three systems water + formaldehyde dimethylhydrazone, NN dimethylhydrazine + formaldehyde dimethylhydrazone, and monomethylhydrazine + water showed, respectively, a rather large positive deviation, a slight positive deviation, and a rather large negative deviation relative to ideal liquid-vapor solution behavior. The solution model attributes the nonideality of the systems to the formation of chemical association species which obey Henry's law in terms of the actual solution equilibrium mole fraction composition. The unreacted species were assumed to obey Raoult's law in terms of actual mole fraction composition. A satisfactory description of the equilibrium liquid-vapor behavior for all three systems was obtained from the model.