The importance of hard core repulsion in models of activity coefficients in aqueous electrolyte solutions: Illustration in the case of hydration theory
Activity coefficients in aqueous electrolyte solutions are primarily affected by two kinds of phenomena. The standard Debye-Huckel equation represents only one of these, the long range electrical interactions. Of nearly equal importance is hard core (HC) repulsion, which is not electrical in nature. To a first-order approximation, HC repulsive effects are independent of the ionic strength, depending instead on the sum of the solute molalities ([Sigma]m). Adding a term for HC repulsion to the standard Debye-Huckel model produces what we call a hybrid two-term model In a previous work (Wolery and Jackson 1990) we proposed a new method for making hydration corrections to the standard Debye-Huckel model. In the present work, we examine the effect of extending this model to include hard core repulsion. Although the activity coefficients of 1:1 electrolytes can be fit quite well by the model without a HC term the inclusion of such a term is critical to success in fitting the data for 2:1 and other higher-order electrolytes.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6567510
- Report Number(s):
- UCRL-JC-109948; CONF-920761-17; ON: DE93012476
- Resource Relation:
- Conference: 7. water-rock interaction conference, Park City, UT (United States), 9-23 Jul 1992
- Country of Publication:
- United States
- Language:
- English
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