Excess Enthalpies of Mixing of Binary Mixtures of NaCl, KCl, NaBr and KBr in Mixed Ternary Solvent Systems at 298.15 K

  • BR Deshwal
  • HK Lee
  • S Maken
  • KC Singh
Keywords: Enthalpy of mixing, ternary solvents, Pitzer theory, Friedman model, cross square rule.

Abstract

Excess enthalpies of mixing for six possible binary combinations of solutions of NaCl, KCl, NaBr and KBr in mixed ternary solvents composed of formamide, 1,4-dioxane and water have been determined using a flow microcalorimeter at constant ionic strengths of 0.500 and 1.000 mol kg–1 at 298.15 K. Unlike the case of water, the data do not supportYoung’s cross square rule. Pitzer’s virial coefficient theory has been utilized to obtain binary and ternary interaction parameters, i.e. θH and ψH. The data were also analysed in terms of the Friedman model and it was found that interactions between solvated ions are dictated not only by coulombic interactions but also by appreciable asymmetric effects.

Keywords: Enthalpy of mixing, ternary solvents, Pitzer theory, Friedman model, cross square rule.

Published
2015-10-05
Section
Articles

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eISSN: 0379-4350