Kinetics of the oxidation of formic acid by aquacobalt(III) ions in aqueous perchlorate media
Abstract
The rate of oxidation of formic acid by CoIIIaq has been measured in aqueous perchlorate media over a wide range of conditions using conventional and stopped-flow spectrophotometry. The order in [CoIII] is unity and the order in [HCOOH] lies between zero and unity; the rate decreases with increasing acidity in a complex manner. The mechanism is resolved into two rate determining processes, each involving an intermediate CoIII—HCOOH complex. These two complexes have an acid–base relationship involving two protons. Values for ΔH* and ΔS* together with the ratio of rates of oxidation of HCOOH and DCOOH are compared for a range of oxidizing ions.