The Investigation of Equilibria in Solution
M. Maedera and H. Abdollahib,*
aDepartment of Chemistry, University of Newcastle, Australia
bInstitute of Advanced Studies in Basic Sciences, Zanjan, Iran
This contribution describes the practical and computational aspects relevant for the quantitative analysis of chemical equilibria. First a systematic nomenclature based on stability constants is introduced. Next, practical aspects of potentiometric pH titrations and spectrophotometric titrations are discussed. The description of the computational aspects includes the Newton-Raphson algorithm that allows the computation of all species concentrations for a given model, set of formation constants and total component concentrations. The second computational part introduces the Newton-Gauss algorithm for non-linear data fitting. Three practical examples illustrate all the above. They include the spectrophotometric investigations of the interaction of Bi(III) with Cl-, of Cu(II) with EDTA and the potentiometric investigation of the Zn(II) ethylenediamine system. All Matlab softwares for the data generation and analysis are available from the authors.
Keywords: Chemical equilibrium, Titration, Non-linear least-squares fitting, Protonation equilibria, Complexation equilibria