Determination of sulfuric acid first dissociation constants to 400°C and 32 MPa by potentiometric pH measurements

Kiwamu Sue, Munehiro Uchida, Tadafumi Adschiri, Kunio Arai

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

pH of 10-3 mol kg-1 H2SO4 aqueous solutions at subcritical and supercritical conditions was measured at temperatures from 375.0 to 400.6°C and pressures from 25.8 to 32.5 MPa by a flow-through electrochemical cell and it changed from 3.90 at 375.2°C and 32.5 MPa to 6.37 at 399.8°C and 28.1 MPa. The molal equilibrium constant for the dissociation reaction of H2SO4 was determined based on the measured pH and the value varied from 1.67×10-7 at 399.8°C and 28.1 MPa to 4.53×10-4 at 375.2°C and 32.5 MPa. The values were between the literature values determined from UV-Vis spectroscopy and electrical conductivity. An empirical density model for the description of the temperature and pressure dependence of the equilibrium constants was used to correlate the data.

Original languageEnglish
Pages (from-to)295-299
Number of pages5
JournalJournal of Supercritical Fluids
Volume31
Issue number3
DOIs
Publication statusPublished - 2004 Nov 1

Keywords

  • Dissociation constant
  • Flow-through electrochemical cell
  • Potentiometric measurement
  • Sulfuric acid
  • Supercritical water
  • pH

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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