Thermodynamics of protonation and sodium binding of sulfate in concentrated NaCl and CsCl solutions studied by Raman spectroscopy

Steven Kratsis, Glenn Hefter, Peter M. May, Pal Sipos

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The protonation constant (pKa) of SO42-(aq) has been determined at ionic strengths 0.5 M ≤ I ≤ 4.0 M in NaCl and CsCl media at 25°C by using Raman spectroscopy. These data were used to calculate the association constant of the NaSO4- (aq) ion pair in CsCl media. The results are in excellent agreement with previous values obtained by other techniques. The pKa was also measured at I = 4 M in both media at temperatures up to 85°C and the associated enthalpy and entropy changes were calculated. However, reliable thermodynamic data for the ion-pairing reaction could not be obtained at higher temperatures probably because of competition from CsSO4-(aq).

Original languageEnglish
Pages (from-to)363-367
Number of pages5
JournalAustralian Journal of Chemistry
Issue number5
Publication statusPublished - Jan 1 2000



  • Caesium chloride
  • Enthalpy
  • Entropy
  • Ion pair
  • Protonation
  • Raman spectroscopy
  • Sodium chloride
  • Sulfate

ASJC Scopus subject areas

  • Chemistry(all)

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