Potentiometric determination of the first hydrolysis constant of gallium(III) in NaCl solution to 100°C

Miho Uchida, Akitsugu Okuwaki

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8 Citations (Scopus)

Abstract

The hydrolysis equilibrum of gallium (III) solutions in aqueous 1 mol-kg-1 NaCl over a range of low pH was measured potentiometrically with a hydrogen ion concentration cell at temperatures from 25 to 100°C at 25°C intervals. Potentials at temperatures above 100°C increased gradually because of further hydrolysis of the gallium(III) ion, followed by precipitation. The results were treated with a nonlinear least-squares computer program to determine the equilibrium constants for gallium(III)-hydroxo complexes using the Debye-Hückel equation. The log K (mol-kg-1) values of the first hydrolysis constant for the reaction, Ga3+ + H2O ⇆ GaOH2+ + H+ were -2.85 ± 0.03 at 25°C, -2.36 ± 0.03 at 50°C, -1.98 ± 0.01 at 75°C, and - 1.45 ± 0.02 at 100°C. The computed standard enthalpy and entropy changes for the hydrolysis reaction are presented over the range of experimental temperatures.

Original languageEnglish
Pages (from-to)965-978
Number of pages14
JournalJournal of Solution Chemistry
Volume27
Issue number11
DOIs
Publication statusPublished - 1998 Nov

Keywords

  • Enthalpy
  • Entropy
  • Gallium(III)
  • Hydrolysis
  • Potentiometry
  • Temperalure dependence
  • Thermodynamics

ASJC Scopus subject areas

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

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