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2010 | 8 | 2 | 392-395
Tytuł artykułu

Spectrophotometric determination of aqueous acidity constants of three azo dyes

Treść / Zawartość
Warianty tytułu
Języki publikacji
EN
Abstrakty
EN
The two successive steps acidity constants of three azo dye derivatives D1–D3, were determined by a spectrophotometric method using 0.10 M KNO3 as supporting electrolyte in water solvent. The electronic spectra of the compounds were recorded in the course of their pH-metric titration with a standard base solution. The protolytic equilibrium constants can be solved very satisfactorily from absorbance data, by combining the data obtained in the spectrometric determinations with graphic methods as the absorbance diagrams. An A-diagram shows the relative absorbance changes at two wavelengths as a function of the pH. For a one-step system, the absorbance at any wavelength must be proportional to the absorbance at any other wavelength, so an A-diagram for all wavelength combinations for such a system must be linear (rank, s=1). However, if a system is governed by two or more equilibria, the A-diagrams corresponding to multi-step titrations will change direction every time a new equilibrium becomes dominant in the system. Analysis of the each uniform sub-region can then be used in evaluating of the corresponding equilibrium. A-diagrams for all wavelength combinations suggest that these systems have the rank two(s=2). The results revealed that the Ka(1) and Ka(2) values of different azo dyes follow the order D3>D2>D1. [...]
Wydawca

Czasopismo
Rocznik
Tom
8
Numer
2
Strony
392-395
Opis fizyczny
Daty
wydano
2010-04-01
online
2010-03-23
Twórcy
  • Department of Chemistry, Lorestan University, Khorramabad, 6813717133, Iran, Alizadehk@yahoo.com
  • Department of Chemistry, Lorestan University, Khorramabad, 6813717133, Iran
  • Department of Chemistry, Imam Hossein University, Tehran, 1731834341, Iran
Bibliografia
  • [1] J. Havel, M. Meloun, Computation Methods for the Determination of Formation Constants (Plenum Press, New York, 1985)
  • [2] H. Gammp, M. Maeder, C.J. Meyer, A.D. Zuberbuhler, Talanta 32, 257 (1985)
  • [3] J. Ghasemi, A. Niazi, M. Kubista, A. Elbergali, Anal. Chim. Acta 455, 335 (2002) http://dx.doi.org/10.1016/S0003-2670(01)01623-3[Crossref]
  • [4] L. Antonov, G. Gorgov, V. Petrov, M. Kubista, J. Nygren, Talanta 49, 99 (1999) http://dx.doi.org/10.1016/S0039-9140(98)00348-8[Crossref]
  • [5] J. Polster, H. Lachmann, Analysis of Chemical Equilibria (VCH, Weinheim, 1989)
  • [6] K. Haghbeen, E. Tan, J. Org. Chem. 63, 4503 (1998) http://dx.doi.org/10.1021/jo972151z[Crossref]
Typ dokumentu
Bibliografia
Identyfikatory
Identyfikator YADDA
bwmeta1.element.-psjd-doi-10_2478_s11532-010-0001-7
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