Reduction of Trioxobromate(V)Ion By [Cohedtaoh21- in Acid Medium : Kinetics and Mechanism

Abstract

The kinetics of the reduction of trioxobromate(V)ion, Bro; by [CoHEDTAOH2T has been studied in aqueous acidic medium at 28 ^oc, I = 1.0 mol dni³ (NaC104) and [1-1+1 = 7.50x10² mol dm-3. The stoichiometry studies showed that for every mole of the Bro; , 5 moles of [CollEDTAOH2T was consumed. The stoichiometric equation for the reaction is: 5[C0HEDTAOH2T + Bro; + 611⁴ 5[CoHEDTAOH21 + + 3H20. The reaction isfirst order in both [Bro;] and [CollEDTAOHil. The rate of the reaction increased with increase in       l. A plot of acid de endent rate constants versus IH+/² is linear and conform to thefollowing equation: - [CoHEDTAOHi1 /dt = (a + b[H+] ) [CoHEDTAOHi] [Bro;] within the acid range 0.025S [H+] 4.1 moldni , a = 6.0 x 10-5 dm mol ^Is ^I and b= 0.146 dm%not³s ^INegative salt effect was observed from the rate dependence on ionic strength studies. CH3COO- decreased the rate of the reaction. The outer-sphere mechanism is proposedfor the reaction.