Phase relations in the system NaCl-KCl-H2O: V. Thermodynamic-PTX analysis of solid-liquid equilibria at high temperatures and pressures

S. Michael Sterner, I. Ming Chou, Robert T. Downs, Kenneth S. Pitzer

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


The Gibbs energies of mixing for NaCl-KCl binary solids and liquids and solid-saturated NaCl-KCl-H2O ternary liquids were modeled using asymmetric Margules treatments. The coefficients of the expressions were calibrated using an extensive array of binary solvus and solidus data, and both binary and ternary liquidus data. Over the PTX range considered, the system exhibits complete liquid miscibility among all three components and extensive solid solution along the anhydrous binary. Solid-liquid and solid-solid phase equilibria were calculated by using the resulting equations and invoking the equality of chemical potentials of NaCl and KCl between appropriate phases at equilibrium. The equations reproduce the ternary liquidus and predict activity coefficients for NaCl and KCl components in the aqueous liquid under solid-saturation conditions between 673 and 1200 K from vapor saturation up to 5 kbar. In the NaCl-KCl anhydrous binary system, the equations describe phase equilibria and predict activity coefficients of the salt components for all stable compositions of solid and liquid phases between room temperature and 1200 K and from 1 bar to 5 kbar.

Original languageEnglish (US)
Pages (from-to)2295-2309
Number of pages15
JournalGeochimica et Cosmochimica Acta
Issue number6
StatePublished - Jun 1992
Externally publishedYes

ASJC Scopus subject areas

  • Geochemistry and Petrology


Dive into the research topics of 'Phase relations in the system NaCl-KCl-H<sub>2</sub>O: V. Thermodynamic-PTX analysis of solid-liquid equilibria at high temperatures and pressures'. Together they form a unique fingerprint.

Cite this