A GENERALIZED MULTICOMPONENT THERMODYNAMIC MODEL APPLIED TO THE (NH4)(2)SO4-H2SO4-H2O SYSTEM TO HIGH SUPERSATURATION AND LOW RELATIVE-HUMIDITY AT 298.15 K

A mole fraction-based multicomponent thermodynamic model, previously a pplied to the system H2O-H2SO4, is here extended to mixtures with (NH4 )(2)SO4 at 298.15 K. Model parameters are determined by fitting to vap our pressure data (from isopiestic and electrodynamic balance studies) , together with degrees of dissociation of the bisulphate ion and salt solubilities (solid phases (NH4)(2)SO4, (NH4)(3)H(SO4)(2) and NH4HSO4 ). The model successfully represents the thermodynamic properties of t he system to high supersaturation over the full range of composition f rom (NH4)(2)SO4-H2O to H2SO4-H2O. Equilibrium vapour pressures of NH3 have been calculated for mixtures of various compositions.