Understanding Complexometric Titrations of Metal Cations with Aminopolycarboxylic Acids (EDTA and Analogs) within the frame of the Notion of Reactions between Groups of Chemical Species

Maria Michela SALVATORE^1, and Francesco SALVATORE¹

¹Dipartimento di Scienze Chimiche, Università degli Studi di Napoli “Federico II”, Via Cintia, 21 - 80126 Napoli, Italy

Cite this paper:
Maria Michela SALVATORE and Francesco SALVATORE. Understanding Complexometric Titrations of Metal Cations with Aminopolycarboxylic Acids (EDTA and Analogs) within the frame of the Notion of Reactions between Groups of Chemical Species. World Journal of Chemical Education. 2015; 3(1):5-21. doi: 10.12691/wjce-3-1-2

Abstract

In spite of the apparent technical simplicity with which visual complexometric titrations of metal cations with aminopolycarboxylic acids titrants are performed, a complex chemistry takes place in the titrated solution during the titration, due to the chemical environment and to the insuppressible chemical properties of metal cations, aminopolycarboxylic acids and metallochromic indicators. This chemical complexity makes rigorous exposition and evaluations of complexometric titrations arduous. Nonetheless, by the introduction of the notions of groups of chemical species and reactions between groups of chemical species (with the connected concept of conditional formation constant), a frame is created within which complexometric titrations with aminopolycarboxylic acids can be collocated and which allows a reasonably simple presentation and evaluation of the analytically relevant aspects of this type of titrations. In a sense, the well known concept of conditional complex formation constant is updated in a way that facilitates understanding and use.

Keywords:
aminopolycarboxylic acids complexometric titrations conditional formation constant EDTA magnesium Eriochrome Black T water hardness

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References:

[1]	Hart, J. R., Ethylenediaminetetraacetic Acid and Related Chelating Agents" in Ullmann's Encyclopedia of Industrial Chemistry, © Wiley-VCH, Weinheim, 2005.
[2]	Hage, D. S., Carr, J. D., Analytical Chemistry and Quantitative Analysis, © Pearson Education Inc., Prentice Hall, N. J., 2011.
[3]	Skoog, D.A., West, D. M., Holler, F. J., Fundamentals of Analytical Chemistry, 7th ed., Saunders College Publishing, Philadelphia 1996.
[4]	Prĭbil, R., Applied Complexometry, Pergamon Series in Analytical Chemistry Volume 5, © Pergamon Press Ltd., Oxford, 1982.
[5]	Ringbom, A., Complexation Reactions, Chapter 14 in Kolthoff, I.M., Elving, P.J. and Sandell, E.B. (eds), Treatise on analytical chemistry, © The Interscience Encyclopedia, Inc., New York, 1959.
[6]	Wilson, C.M., Wilson, D.W., Comprehensive Analytical Chemistry, Vol. IB, © Elsevier Publishing Company Inc., New York, 1960.
[7]	Smith, R.M., Martell, A.E., Critical stability Constants, Vol. 1-4, © Plenum Press, New York, 1976.
[8]	Burgot J. L., Ionic Equilibria in Analytical Chemistry, © Springer Science+Businiss Media, New York, 2012.
[9]	Salvatore, F., Introduzione all’Uso Analitico delle Reazioni di Formazione di Complessi, © CUES editrice s.r.l., Fisciano, Italy, 2011.