Thermodynamics of Electrolyte Solutions.
Abstract
Thermodynamics of electrolyte solutions has been studied and a new equation of state for mixtures containing electrolytes has been derived using perturbation theory. In this equation, shortrange interactions between molecules are calculated using the PerturbedAnisotropicChain theory (PACT) of Vimalchand and Donohue. A perturbation expansion based on Henderson's restricted primitive model is used for chargecharge interactions among ions. Solvation effects caused by chargemolecule interactions very near ions are taken into account through an effective dielectric constant. Additional new expressions, a thirdorder perturbation expansion for chargedipole interactions and a firstorder perturbation expansion for chargeinduced dipole interactions, were derived for interactions of ions with molecules in the bulk of solution. This equation of state contains four parameters: s, number of segments per particle, q, normalized surface area per particle, epsilon, a characteristic energy per unit external surface area of a particle, and c, onethird number of external degree of freedom. For neutral molecules, these parameters have been determined using PACT by fitting simultaneously experimental vapor pressure and liquiddensity data. For ions, the parameters are calculated using literature values for polarizability and ionic radius which are adjusted by an ionic size parameter, C_{s}. In this work, preliminary calculations involving mean ionic activity coefficients for fifty strong electrolytes in water, specific volumes of several strong aqueous solutions, K factors for argon and methane in aqueous solutions of NaCl and aqueous solutions of KOH and vaporliquid equilibra for aqueous solutions containing volatile weak electrolytes are carried out. The results show the usefulness of this new equation of state. In these caulations, the ionic size parameter, C_{s}, is the only adjustable parameter used for strong electrolytes over a range of molarity form infinite dilution to 6 molal. The calculations involving weak electrolytes here are carried out without using any adjustable mixture parameter. Average absolute errors are less than 5% for activity coefficients of most strong electrolytes in water, 1.5% for specific volumes for the two electrolyte systems tested, 5% for partial pressures of weak electrolytes in water, and 5% for K factors for the ternary systems containing strong electrolytes.
 Publication:

Ph.D. Thesis
 Pub Date:
 December 1989
 Bibcode:
 1989PhDT........26J
 Keywords:

 Engineering: Chemical; Physics: Molecular