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Title: | Kinetic study of the complexation of chromium(III) by L-glutamic acid |
Other Titles: | Estudi cinètic de la complexació de crom(III) per l’àcid L-glutàmic |
Author: | Nicolàs Rivasés, Joan |
Director/Tutor: | Pérez de Benito, Joaquín F. |
Keywords: | Crom Reaccions químiques Cinètica química Treballs de fi de grau Chromium Chemical reactions Chemical kinetics Bachelor's theses |
Issue Date: | Jun-2017 |
Abstract: | The complexation of chromium(III) by L-glutamic acid / hydrogen L-glutamate ion in aqueous media under slightly acidic conditions (pH 2.46 - 5.87) has been studied by the use of UV-Vis spectroscopy. Although the reaction in the presence of a large excess of organic ligand is considered in the chemical literature to be a pseudo-first order kinetic process, the rate-time plots corresponding to the formation of the reaction product show a distinct bell-shaped profile, caused by the accumulation of a long-lived intermediate. Given that this intermediate is not reactive enough for the steady state approximation to apply, an integrated rate law involving a double-exponential function has been used to obtain two rate constants for each kinetic experiment, corresponding to the formation of the long-lived intermediate from the reactants (k1) and to its decay into the reaction products (k2). Both rate constants increased with the initial concentration of hydrogen L-glutamate ion in a double-reciprocal linear relationship, k1 decreased with the ionic strength whereas k2 increased, both evidenced the existence of base catalysis and the corresponding activation energies were 83 ± 10 and 95 ± 5 kJ mol-1, respectively. The spectroscopic data indicated the formation of several complexes, differing in the number of organic ligands per chromium atom and in their acid-base properties. A mechanism in agreement with the available experimental data has been proposed, involving the breakage of a Cr(III)-aqua chemical bond as a previous step to the coordination of the organic ligand |
Note: | Treballs Finals de Grau de Química, Facultat de Química, Universitat de Barcelona, Any: 2017, Tutor: Joaquín F. Pérez de Benito |
URI: | http://hdl.handle.net/2445/116062 |
Appears in Collections: | Treballs Finals de Grau (TFG) - Química |
Files in This Item:
File | Description | Size | Format | |
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Nicolas Rivases Joan.pdf | 1.23 MB | Adobe PDF | View/Open |
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