A KINETIC-STUDY OF THE AUTOCATALYTIC PERMANGANATE OXIDATION OF FORMIC-ACID

The kinetics of the permanganate oxidation of formic acid in aqueous perchloric acid has been studied. The results indicate that this reaction is autocatalyzed by both manganese(II) ion (formed as a reaction product) and colloidal manganese dioxide (formed as an intermediate). The apparent rate constants corresponding to the noncatalytic and autocatalytic reaction pathways are given, respectively, by the following equations (Formula Presented.) The activation energies associated with the true rate constants, 𝓀 1bc, 𝓀 1nc, 𝓀 1ac, 𝓀 2bc, 𝓀 2nc, and 𝓀 2ac are 37.2, 62.5, 70.9, 52.5, 40.8, and 59.9 kJ mol−1, respectively. The percentage of the total reaction corresponding to each pathway is given for typical experimental conditions. Mechanisms in agreement with the kinetic data are proposed for the six different reaction pathways observed. Copyright © 1990 John Wiley & Sons, Inc.