Electrical conductivity measurements are able to provide quantitative information about transport properties and chemical speciation. These measurements are therefore useful to engineers in the design of flow systems for industry, such as those used in the production of electric power. Accordingly, simple-to-use equations that cover wide ranges of temperature and pressure are useful in the industrial world and geochemical community. To this end, experimental conductivity measurements of aqueous potassium chloride (KCl) from the scientific literature were used to calculate the conductivity at infinite dilution, Λ°, and ion-pair association constant, KA, over a wide range of temperatures, by means of the Fuoss-Hsia-Fernandez-Prini (FHFP) conductivity model of electrolytes. A simple exponential function of viscosity and density was then fit to the resulting Λ°. The final fit equation expressed the experimental Λ° to less than the estimated uncertainties with only a few exceptions. This simple equation was found to represent the temperature and pressure dependence of calculated Λ° [KCl(aq)] better than any other previously published equations. The Λ° values were also split to give the individual ionic contributions, λ°, using a temperature-dependent equation for KCl(aq) transference number data. A model based on the density and temperature was also fitted to the experimental KA values, establishing a global thermodynamic picture of the aqueous KCl system over a wide range of temperatures and pressures.

Equations for calculating limiting conductivities and ion-pair association constants for aqueous KCl under hydrothermal conditions

255th National Meeting (2018)

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