Portal de Periódicos da CAPES

Thermodynamics of electrolytes. V. effects of higher-order electrostatic terms

1975; Springer Science+Business Media; Volume: 4; Issue: 3 Linguagem: Inglês

10.1007/bf00646562

1572-8927

Kenneth S. Pitzer,

Chemical Thermodynamics and Molecular Structure

The contribution of higher-order electrostatic terms (beyond the Debye-Hückel approximation) to the thermodynamic properties of mixed and pure electrolytes is investigated. It is found that these effects are important for cases of unsymmetrical mixing, especially when one ion has a charge of three units or more. The appropriate correction can be made by a purely electrostatic function since the mutual repulsion of ions of the same sign keeps them far enough apart that short-range forces have little effect. This function is evaluated, and several convenient approximations are also given. Application is made to systems mixing ions of the type 1–2 and 1–3. Higher-order limiting laws exist for symmetrical mixtures and for pure, unsymmetrical solutes, but these effects were not found to be significant in relationship to existing activity or osmotic-coefficient data.