Systematic design of chemical oscillators. 60. Kinetics and mechanism of the reaction between chlorite ion and hypochlorous acid

Kinetics and mechanism of the oxidation of Coomassie Brilliant Blue-R dye by hypochlorite and role of acid therein

“…Coomassie Brilliant Blue-R (FW = 825) (Aldrich), sodium hydroxide (BDH), 98 % sulfuric acid (BDH) and anhydrous sodium sulfate (Univar) were used as supplied. The hypochlorite solutions were prepared as per the procedure described by Nagypal et al, 22 and were standardized by iodometric titration. Standardized solutions of sulfuric acid (0.1 M) or sodium hydroxide (0.1 M) were used to adjust the pH and sodium sulfate was used to maintain the ionic strength.…”

Kinetics and Mechanism of the Chlorine Dioxide-Tetrathionate Reaction

“…As part of the attempt to elucidate the mechanism of the fascinating chlorite-thiosulfate reaction, several subsystems of the parent reaction have been investigated. The kinetics and mechanisms of the chlorite-hypochlorous acid, 5 thiosulfate-chlorine dioxide, 6 tetrathionate-hypochlorous acid, 7 and chlorine dioxidehypochlorite 8 reactions have been established. It has also been shown 4 that at least two long-lived intermediates, chlorine dioxide and the tetrathionate ion, formed in the chloritethiosulfate reaction can be end products as well, depending upon the initial concentration ratio of the reactants.…”

Oscillations and Mechanistic Analysis of the Chlorite−Sulfide Reaction in a Continuous-Flow Stirred Tank Reactor

“…The value of k 9a is 1.1 × 10 6 M -2 s -1 at pH 5-6 and 25°C, 26,27 which implies that k 9a [H + ] ) k 9 is 1.1-11 M -1 s -1 . Under our experimental conditions, the pH oscillates between 5 and 6 at T ) 32°C, so k 9 ) k 9a [H + ] is expected to be larger than that at T ) 25°C.…”

“…Reactions 6 and 7 were studied by Frerichs et al, 22 and we adopt their rate constants. Reaction 8 is a protonconsuming process, for which we use the rate law and rate constant reported by Peintler et al 26 Reaction 9 is another H + -formation process, which involves two steps:…”

“…We include them, however, because they do have small effects on the amplitude and frequency of the simulated oscillations and because the species involved should be significant at pH 5-6. 25,26 …”