Kinetics of the bromate-bromide reaction at high bromide concentrations

At 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)(k(1)[Br-]+k(2)[Br-](2)). In perchloric solutions at 25 degrees C k(1) = 2.18 dm(3) mol(-3) s(-1) and k(2) = 0.65 dm(4) mol(-4) s(-1) at 1 M ionic strength and k(1) = 2.60 dm(3) mol(3) s(-1) and k(2) = 1.05 dm(4) 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. (c) 2006 Wiley Periodicals, Inc.