Clarifying the Equilibrium Speciation of Periodate Ions in Aqueous Medium

László Valkai, G. Peintler, A. Horváth

Research output: Contribution to journalArticle

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Abstract

Equilibria of periodate ion were reinvestigated in aqueous solution by using potentiometric titration, UV and Raman spectroscopies, and gravimetry simultaneously at 0.5 M ionic strength and at 25.0 ± 0.2 °C. Stepwise acid dissociation constants of orthoperiodic acid were found to be pK1 = 0.98 ± 0.18, pK2 = 7.42 ± 0.03, and pK3 = 10.99 ± 0.02, as well as pK2 = 7.55 ± 0.04 and pK3 = 11.25 ± 0.03 in the presence of sodium nitrate and sodium perchlorate as background salts, respectively. pK1 cannot be determined unambiguously from our experiments in the presence of sodium perchlorate. The molar absorptivity spectrum of H4IO6- and H3IO62- was determined in the range of 215-335 nm, as major species of periodate present from slightly acidic to slightly alkaline conditions. The solubility of periodate decreases significantly under alkaline conditions, and it was determined to be (2.8 ± 0.4) mM by gravimetry, under our experimental conditions. None of these studies gave any clear evidence for an ortho-meta equilibrium and the frequently invoked dimerization of periodate. All measurements can quantitatively be described by the presence of orthoperiodic acid and its three successive deprotonation steps.

Original languageEnglish
Pages (from-to)11417-11425
Number of pages9
JournalInorganic Chemistry
Volume56
Issue number18
DOIs
Publication statusPublished - Sep 18 2017

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gravimetry
perchlorates
acids
Gravimetric analysis
sodium
Acids
sodium nitrates
ions
dimerization
titration
spectroscopy
Deprotonation
Dimerization
absorptivity
solubility
Raman spectroscopy
Ionic strength
Ultraviolet spectroscopy
Titration
dissociation

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

Cite this

Clarifying the Equilibrium Speciation of Periodate Ions in Aqueous Medium. / Valkai, László; Peintler, G.; Horváth, A.

In: Inorganic Chemistry, Vol. 56, No. 18, 18.09.2017, p. 11417-11425.

Research output: Contribution to journalArticle

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