The kinetics and mechanism of the reaction of ethylene-diamine-tetraacetato manganese (II) and peroxydisulphate ion in aqueous acidic solutions

Chemistry Dept, Faculty of Science, Ain-Shams University, Abbassia, Cairo, Egypt.

Abstract

Peroxydisulphate ion readily oxidises Mn(ll) Y [Y = Ethylenedia-minetetraacetate] with the formation of an intermediate complex in low acid concentration (pH > 3),

Where the Rate [Math]

and the rate [Math]

at high acid concentration (pH < 3).

Where [S₂O₈^2-] is the total peroxydisulphate concentrations, k_H is the rate constant for the electron transfer process and k_H is the prc-eguilibrium protonation constant. The values of k and k_H and K_H were determined at 53 °C. Activation energy and activation entropy for the reaction were determined from Arrhenius plots.

Résumé

L'ion peroxydisulfate oxyde aisément Mn(ll) Y (Y = EDTA) avec formation d'un complexe intermédiare aux Ph peu acides. Expression de la vitesse aux Ph faiblement ou fortement acides. Expression de la constante de vitesse pour le transfert d'electron et de la constante de protonation avant l'equilibre, ces deux valeurs déterminées a 53 °C. Determination de l'energie et de l'entropie d'activation de la reaction.