The kinetics of the bromate–sulfite reaction system

The kinetics of the reaction between BrO₃⁻ and sulfite was studied by measuring the concentrations of Br⁻] and H⁺] both in buffered and in unbuffered solutions. A mechanism was applied for simulation of the experimental observations. Rate constants k₁=(0.027±0.004) M⁻¹s⁻¹ and k₂=(85±5) M⁻¹s⁻¹ were determined for the following reactions: \halign{\hfill $#$\hfill &\hfill\qquad\qquad #\cr 3\ \rm HSO_{3}\!^{-}+BrO_{3}\!^{-}\longrightarrow 3\ SO_{4}\!^{2-}+Br^{-}+3\ H^{+}& (1)\cr 3\ \rm H_{2}SO_{3}(\hbox{or}\ SO_{2.}\hbox{aq})+BrO_{3}\!^{-}\longrightarrow 3\ SO_{4}\!^{2-}+Br^{-}+6\ H^{+}& (2)\cr } Rate constant k₁ was obtained directly from the experimental results on unbuffered reactions, where Reaction (1) was predominant. Rate constant k₂ was obtained by computer fitting of Br⁻] to the experimental values for buffered reactions, where the rate of Reaction (2) was about four times higher than that of Reaction (1). © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 869–874, 1998