How do you model thermodynamics of electrolyte solutions?

Electrolyte solutions require special treatment due to ionic dissociation and long-range electrostatic interactions. Key considerations: chemical equilibria (dissociation, speciation), Debye-Huckel term for long-range ion-ion interactions, and short-range interactions (NRTL-type). Common models: Electrolyte-NRTL (e-NRTL) in Aspen, Pitzer model for aqueous systems, OLI for comprehensive speciation. Parameters needed: dissociation constants (temperature-dependent), ion-pair interaction parameters, and reference state (infinite dilution). Applications: acid gas treating (amine systems), chlor-alkali, and pharmaceutical crystallization. Mean ionic activity coefficient replaces component activity coefficient for ionic species.