Kinetic Approach to the Reduction of Ethylenediaminetetraacetatoferrate(III) Complex by Iodide Ion in Aqueous Acidic Medium

Main Article Content

I. U. Nkole
C. R. Osunkwo

Abstract

The kinetic approach to the reduction of ethylenediaminetetraacetatoferrate(III) complex (hereafter [Fe(III)EDTA]-) by iodide ion has been studied spectrophotometrically in an aqueous acidic medium. The study was carried out under pseudo-first order conditions of an excess of iodide ion concentration at 28 ± 1, ionic strength (I) = 0.43 coulomb2 mol dm-3 (KNO3) and [H+] = 5.0  10-2 mol dm-3. The [Fe(III)EDTA]- complex was reduced according to the reaction;

2[Fe(III)EDTA]- + 2I-  → 2[Fe(II)EDTA]2- + I2

The rate law is - d[Fe(III)EDTA-]/dt = (a + b[H+])[Fe(III)EDTA-][I-]

The rate of the reaction is first order in oxidant and reductant concentrations, and displayed positive Brønsted-Debye salt effect. On the basis of catalysis by added cation, Michaelis-Menten plots and the absence of intermediates, the outer-sphere electron transfer mechanism is proposed for the reaction.

Keywords:
Kinetics, mechanism, iodide, reduction, ethylenediaminetetraacetatoferrate(III) complex.

Article Details

How to Cite
Nkole, I. U., & Osunkwo, C. R. (2019). Kinetic Approach to the Reduction of Ethylenediaminetetraacetatoferrate(III) Complex by Iodide Ion in Aqueous Acidic Medium. Asian Journal of Physical and Chemical Sciences, 7(2), 1-8. https://doi.org/10.9734/ajopacs/2019/v7i230091
Section
Original Research Article

References

Fierro S, Comninellis C, Einaga Y. Simultaneous detection of iodine and iodide on boron doped diamond electrodes. Talanta. 2012;103:33–37.
Available:http://dx.doi.org/10.1016/j.talanta.2012.10.002

Küpper FC, Carpenter LJ, McFiggans GB. Iodide accumulation provides kelp with an inorganic antioxidant impacting atmospheric chemistry. Proceedings of the National Academy of Sciences of the United States of America. 2008;105:6954–6958.
Available:http://dx.doi.org/10.1073/pnas.0709959105

Nord G, Pedersen B, Farver O. Outer-sphere oxidation of iodide and thiocynate by tris(2,2’-bipyridyl)- and tris(1, 10-phenanthroline) osmium(III) in aqueous solutions. Inorganic Chemistry. 1978;17:2233–2238.
Available:http://dx.doi.org/10.1021/ic50186a043

Fabian I, Gordon G. The kinetics and mechanism of the chlorine dioxide – Iodide ion reaction. Inorganic Chemistry. 1997;36:2494–2497.
Available:http://dx.doi.org/10.1021/ic961279g

Hubbard CD, Gerhard A, Rudivan E. Electrostriction and counter ion effects on an outer-sphere electron transfer reaction, kinetics of the reduction of hexachloroiridate(IV) by iodide ion. Journal of Chemical Society, Dalton Transaction. 2001;1069–1075.
Available:http://dx.doi.org/10.1039/b009363g

Xiao-juan Y, Lin Y, Li D, Xiang-Li L, Wei-Kang Y. Kinetics of the [Fe(III)EDTA]- reduction by sulfite under the catalysis of activated carbon. Journal of American Chemical Society. 2011;25:4248–4255.
Available:https://doi.org/10.1021/ef2006063

Suchecki TT, Mathews B, Kumazawa H. Kinetic study of ambient-temperature reduction of Fe(III)-edta by Na2S2O4. Industrial & Engineering Chemistry Research. 2005;44:4249.
Available:https://doi.org/10.1021/ie0493006

Mendelsohn MH, Harkness JBL. Enhanced flue-gas denitrification using ferrous-EDTA and a polyphenolic compound in an aqueous scrubber system. Energy Fuel. 1991;5:244:10.
Available:https://doi.org/1021/ef00026a003

Onu AD, Iyun JF, Idris SO. Oxidation of ethylenediaminetetraactatocobaltate(II) complex by hydrogen peroxide in aqueous acidic medium: A kinetic study. Journal of Nigerian Chemical Society. 2016;41:81–86.

Iyun JF. The oxidation of some tris-(diimine)iron(II) and tris-(substituted diimine)iron(II) complexes by aqueous acidic bromine solution. An assessment of the marcus model for non - complimentary reactions. Chem Class Journal. 2004;59-63.

Idris SO, Iyun JF, Agbaji EB. Kinetics and mechanism of oxidation of thiosulfate ion by tetrakis(2,2-bipyridine)-µ-oxodiiron(III) ion in aqueous acidic medium. Chem Class Journal. 2008;103–108.

Stephen M. Identification of iron(II) and (III) cations by precipitation reactions; 1997.
Available:http://www.marz-kreations.com/Chemistry/Cation-ID/162k-Iron.html
[Accessed 23rd November, 2017]

Tomasz TS, Barbara M, Hidehiro K. Kinetic study of ambient-temperature reduction of Fe111edta by Na2S2O4. Industrial & Engineering Chemistry Research. 2005;44:4249–4253.
Available:https://doi.org/10.1021/ie0493006

Taqui Khan MM, Martell AE. The kinetics of the reaction of iron(III) chelate of aminopolycarboxylic acid with ascorbic acid. Journal of the American Chemical Society. 1968;90:3386–3389.
Available:https://doi.org/10.1021/ja01015a016

Wubs HJ, Beenackers AACM. Kinetics of H2S absorption into aqueous ferric solutions of EDTA and HEDTA. AlChE Journal. 1994;40:433–444.
Available:https://doi.org/10.1002/aic.690400307

Cheves W, Richard EP, Tomas W. Kinetics of the decomposition of hydrogen peroxide catalyzed by ferric ethylenediaminetetraacetate complex. Proceedings of the National Academy of Sciences of the USA. 1974;72:140–142.

Bull C, McClune GJ, Fee JA. The mechanism of Fe-EDTA catalyzed superoxide dismutation. Journal of American Chemical Society. 1983;105:5290–5300.
Available:https://doi.org/10.1021/ja00354a019

Onu AD, Iyun JF, Idris SO. The kinetics of the reduction of tetraoxoiodate(VII) by n-(2-hydroxylethyl)ethylenediaminetriacetatocobaltate(II) ion in aqueous perchloric acid. Transition Metal Chemistry. 2009;34:849–853.
Available:https://doi.org/10.1007/s11243-009-9273-1

Brønsted JM. Activities of ions in solution. Journal of Physical Chemistry. 1922;102:106.

Pryztas TJ, Sutin N. Kinetics studies of anion – Assisted outer-sphere electron transfer reactions. Journal of American Chemical Society. 1973;95:5545.

Wilkins RG. Kinetics and mechanism of reactions of transition metal complexes. Second Edition, Wiley-VCH Verlag GmbH & Co. 2002;65–106.
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