Molecular Thermodynamics of Fluid-Phase Equilibria

Appendix I The Ion-Interaction Model of Pitzer for Multielectrolyte Solutions

Section 9.14 gives a brief discussion of the ion-interaction model of Pitzer and expressions for the activity coefficient and the osmotic coefficient of binary (single-electrolyte) solutions. This Appendix gives the genera! expressions for these coefficients for multielectrolyte solutions. Also given are tables that list the ion-interaction parameters and their temperature dependence for several common aqueous electrolytes.

For an electrolyte solution containing w_s kg of solvent s and solutes i, j,… with molalities m_i, m_j,…, Pitzer (1995) assumed that the excess Gibbs energy is

(I-1)¹

¹ Equation (1-1) is the same as Eq. (9-58).

Function f(I) depends on ionic strength ...