The effect of pressure on the ionization of boric acid in aqueous solutions from molal-volume data

Gary K. Ward, Frank J. Millero

Research output: Contribution to journalArticlepeer-review

82 Scopus citations

Abstract

The apparent, φ v, and partial, {Mathematical expression} molal volumes of dilute (0.02 to 0.7 m) aqueous boric acid, B(OH)3, and sodium borate, NaB(OH)4, solutions have been determined from 0 to 50° C from precision density measurements. The φ v of boric acid is a linear function of the first power of concentration. For sodium borate, the Debye-Hückel theoretical limiting law slope for the φ v as a function of the square root of molar concentration is approached at all temperatures studied. The positive deviations at higher concentrations increase with decreasing temperature. The infinite-dilution volume properties of both B(OH)3 and NaB(OH)4 indicate that these solutes behave like "structure breakers" between 0 and 50°C (that is ∂2φ v ° /∂T2 is negative). The volume change for the ionization of boric acid in water {Mathematical expression}, is calculated from the volume data at various temperatures. This volume change has been used to estimate the effect of pressure on the ionization of boric acid solutions from 0 to 50°C and 0 to 1000 bars. The calculated effect of pressure on the ionization is in good agreement with direct measurements.

Original languageEnglish (US)
Pages (from-to)417-430
Number of pages14
JournalJournal of Solution Chemistry
Volume3
Issue number6
DOIs
StatePublished - Jun 1 1974

Keywords

  • Ionization of boric acid
  • effect of pressure
  • molal volume

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Physical and Theoretical Chemistry

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