The kinetics of the complex formation between iron(III)- ethylenediaminetetraacetate and hydrogen peroxide in aqueous solution

Virender K. Sharma, Frank J. Millero, Zoltan Homonnay

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The kinetics of the formation of the purple complex [FeIII(EDTA) O2]3-, between FeIII-EDTA and hydrogen peroxide was studied as a function of pH (8.22-11.44) and temperature (10-40°C) in aqueous solutions using a stopped-flow method. The reaction was first-order with respect to both reactants. The observed second-order rate constants decrease with an increase in pH and appear to be related to deprotonation of Fe III-EDTA ([Fe(EDTA)H2O]-⇔Fe(EDTA)OH] 2-+H+). The rate law for the formation of the complex was found to be d[FeIIIEDTAO2]3-/dt=[(k 4[H+]/([H+]+K1)][Fe III-EDTA][H2O2], where k4=8. 15±0.05×104 M-1s-1 and pK 1=7.3. The steps involved in the formation of [Fe(EDTA)O 2]3- are briefly discussed.

Original languageEnglish
Pages (from-to)3583-3587
Number of pages5
JournalInorganica Chimica Acta
Issue number12
Publication statusPublished - Sep 10 2004



  • EDTA
  • Hydrogen peroxide
  • Iron(iii)
  • Kinetics
  • Peroxo complex

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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