language: en

DOI: 10.1002/zaac.200700542

[Forschungsbericht Research Report]

Zur Problematik individueller thermodynamischer Aktivitätskoeffizienten einzelner Ionensorten in Elektrolytlösungen hoher Konzentration 1)

On the Individual Thermodynamic Activity Coefficients of Single Ion Species in Electrolyte Solutions at High Concentrations 1)

Armin Ferse*
Dresden,
Technische Universität
Bei der Redaktion eingegangen am 10. Oktober 2007.

Abstract. The individual activity coefficients of the single ion species, which are produced by dissociation of aqueous electrolytes, are necessary for the thermodynamic treatment of equilibrations and processes involving electrolytes. The determination of these values is one of the basic quests of electrochemistry and a controversial topic. This problem is unsolvable using classical thermodynamics. In this paper a mathematical method is shown, which can be used to split the mean activity coefficients into the values for the individual ion species of an electrolyte. For this determination the mean activity coefficients have to be expressed in the power form of equation. The concept based on the adaptation of a product function for the concentration development of the mean activity coefficients to the experimental data and their separation into factor functions of a predefined structure, which represent the concentration development of the individual activity coefficients of the single ion species of the electrolyte.

Keywords: Electrochemistry; Electrolyte solutions; Individual activity coefficients; Non-linear regression model; Thermodynamics

1 Einleitung