ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Kinetics and mechanism of the reaction of Cr(VI) with oxalic acid have been studied in presence and absence of H2SO4, HClO4, and CH3COOH by monitoring the formation of Cr(III)-oxalic acid complex at 560 nm. The effect of total [oxalic acid], [Cr(VI)], [H2SO4], [HClO4], and [CH3COOH] on the reaction rate was determined at 30°C. Formation of carbon dioxide was also confirmed. The oxidation rate increases with [oxalic acid] and [CH3COOH] while it decreases with [H2SO4], [HClO4], and pH. The rate law governing the oxidation of oxalic acid over a wide range of conditions is rate=k1 Kes1 [oxalic acid]T [Cr(VI)]T 1+Kes1 [oxalic acid]T, where only undissociated oxalic acid is kinetically active. Kinetic evidence for the formation of a Cr(VI)(SINGLEBOND)oxalic acid 1:1 complex has been obtained and the equilibrium constant for their formation has been determined. The 1:1 complex exists most likely in an open chain form. The rate-limiting step of the oxidation reaction involves the breaking of the C(SINGLEBOND)C bond in the 1:2 complex. Oxidizing ability of Cr(VI) species have been discussed. Mechanism with the associated reaction kinetics is assigned. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 335-340, 1998
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
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