Kinetics of the bromate–bromide reaction at high bromide concentrations

Abstract

AbstractAt bromide concentrations higher than 0.1 M, a second term must be added to the classical rate law of the bromate–bromide reaction that becomes −d[BrO3−]/dt = [BrO3−][H+]2(k1[Br−] + k2[Br−]2). In perchloric solutions at 25°C, k1 = 2.18 dm3 mol−3 s−1 and k2 = 0.65 dm4 mol−4 s−1 at 1 M ionic strength and k1 = 2.60 dm3 mol3 s−1and k2 = 1.05 dm4 mol−4 s−1 at 2 M ionic strength. A mechanism explaining this rate law, with Br2O2 as key intermediate species, is proposed. Errors that may occur when using the Guggenheim method are discussed. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 39: 17–21, 2007