2026-04-13T02:08:32Zhttps://recercat.cat/oai/request

oai:recercat.cat:2445/1219162025-11-19T20:35:16Zcom_2072_1057col_2072_478796col_2072_478917

Two Rate constant kinetic model for the chromium(III)-EDTA complexation reaction by numerical simulations Pérez de Benito, Joaquín F. Crom Reaccions químiques Cinètica química Chromium Chemical reactions Chemical kinetics The complexation reaction of Cr(III) ion in the presence of a large excess of EDTA does not follow a pseudo-first-order kinetics as sometimes suggested. There are two causes for the deviation from this simple behavior: the involvement of a long-lived intermediate, precluding the application of the steady-state approximation, and the autoinhibition provoked by the release of hydrogen ions from the organic ligand to the medium as the final Cr(III)-EDTA violet complex is formed. Numerical simulations have allowed obtaining for each kinetic experiment the values of two rate constants, k1 (corresponding to the formation of the long-lived intermediate from the reactants) and k2 (corresponding to the formation of the final complex product from the long-lived intermediate), as well as the number of hydrogens liberated per molecule of final complex product formed (Hkin). The results indicate that k1 is associated to a fast step (Ea = 87 ± 4 kJ mol-1) and k2 to a slow step (Ea = 120 ± 2 kJ mol-1), whereas the number of hydrogen ions lies within the range 0 < Hkin < 2 in all the kinetic runs. A mechanism in accordance with the experimental data has been proposed. 2018-04-27T07:49:16Z 2018-04-27T07:49:16Z 2017-01-21 2018-04-27T07:49:16Z info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion Versió postprint del document publicat a: https://doi.org/10.1002/kin.21070 International Journal of Chemical Kinetics, 2017, vol. 49, p. 234-249 https://doi.org/10.1002/kin.21070 (c) Wiley, 2017 info:eu-repo/semantics/openAccess Wiley Articles publicats en revistes (Ciència dels Materials i Química Física)