Activity coefficients of NaCl in PEG 4000 + water mixtures at 288.15, 298.15 and 308.15 K

Jaime W. Morales, Héctor R. Galleguillos, María E. Taboada, Felipe Hernández-Luis

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


The electromotive force of the cell containing two ion-selective electrodes (ISE),Na-ISE | NaCl (m), PEG 4000 (Y), H2 O (100 - Y) | Cl-ISE. has been measured at temperatures of 288.15, 298.15, and 308.15 K as a function of the weight percentage Y of PEG 4000 in a mixed solvent. Y was varied between 0 and 25% in five-unit steps and the molality of the electrolyte (m) was between ca. 0.003 and 5 mol kg-1. The values of the standard electromotive force were determined using routine methods of extrapolation, together with Debye-Hückel and Pitzer equations. The results obtained produced good internal consistency for all the temperatures studied. Once the standard electromotive force was determined, the mean ionic activity coefficients for NaCl, the Gibbs energy of transfer from the water to the PEG 4000-water mixture and the primary NaCl hydration number were calculated.

Original languageEnglish
Pages (from-to)120-126
Number of pages7
JournalFluid Phase Equilibria
Issue number2
StatePublished - 25 Jul 2009
Externally publishedYes


  • Activity coefficient
  • Emf
  • Ion-selective electrode (ISE)
  • NaCl
  • PEG 4000


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