The decomposition kinetics of sodium perborate catalysed by ethylenediaminetetrakis (methylenephosphonato) iron (III)

Chemistry Department, Faculty of Science, Ain-Shams University, Abbasia, Cairo, Egypt.

Abstract

The catalysed decomposition of sodium perborate 5-in the presence - of ethylenediaminetetrakis (methylenephosphonato) iron (111); (FeY)^5- (Y is ENTMP) was studied at various temperatures and over the pH range 8.65 - 10.70. The observed rate law is given by:

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where K₁ and K₂ are the specific rate constants for the normal and ternary hydroxo complexes catalysed reaction. Activation enthalpies and activation entropies for the reactions were determined and found (p be Δ H₁ = 24.9 I 2.3 Kj/mol; ΔH₂ =32.2±3.2 Kj/mol and ΔS₁ = -185 ± 20 3/K mol; Δs₂ = -155 ± 16 3J/K mol.

Résumé

La decomposition catalysée du perborate de sodium en presence de l'ethylenediaminetetrakis (methylenephosphonato) iron (III); (FeY)^3- (Y est ENTMP) est étudiée a plusieurs temperatures et à des valeurs de pH entre 8.65 et 10.70. La loi de la vitesse de reaction est donnée par l'equation. s ou K₁ et K₂ sont les constants spécifiques de vitesse constante pour la reaction catalysée des complexes hydroxylés normaux et triples. Les enthalpies d'activité et les entropies d'activité des reactions ont étè determinees et ont les valeurs sut vautes ΔH₁ = 24.9 I 2.5 KJ/mol; ΔH₂ =32.2±3.2 KJ/mol and ΔS₁ = -185 ± 20 3/K mol; Δs₂ = -155 ± 16 3J/K mol.