The partial molal volume and compressibility of Tris and Tris-HCl in water and 0.725m NaCl as a function of temperature

Carmen Rodriguez, Fen Huang, Frank J Millero

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4 Scopus citations


The apparent molal volumes and compressibilities of Tris and Tris-HCl have been determined in water (5-45°C) and 0.725m NaCl (5-25°C). The changes in the volume (δV) and compressibility (δκ) for the dissociation of Tris-H<sup>+</sup>Tris-H<sup>+</sup>=Tris+H<sup>+</sup>as functions of temperature in water and 0.725m NaCl have been determined from these measurements. The values of δV and δκ have been used to determine the effect of pressure on the dissociation constant for Tris-H<sup>+</sup> (K<sup>P</sup>/K<sup>0</sup>).ln(KP/K0)=-{increment}V/(RT)P+0.5{increment}k/(RT)P2These results will be useful in the calibration of pH systems making in-situ measurements at high pressure in seawater. In 0.725. m NaCl at 5. °C and a pressure of 2000. bar, the dissociation constant is reduced by 29%.

Original languageEnglish (US)
Pages (from-to)41-51
Number of pages11
JournalDeep-Sea Research Part I: Oceanographic Research Papers
StatePublished - Oct 1 2015



  • Compressibility
  • Dissociation constant
  • High pressure
  • Partial molal volume
  • Seawater pH
  • Tris buffer

ASJC Scopus subject areas

  • Aquatic Science
  • Oceanography

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