ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
According to our experiments the bromide ion concentration exhibits in the bromate-ascorbic acid-malonic acid-perchloric acid system three extrema as a function of time. To describe this peculiar phenomenon, the kinetics of four component reactions have been studied separately. The following rate equations were obtained:Bromate-ascorbic acid reaction: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} { - d[{\rm BrO}_3^ -]/dt = k_1 [{\rm BrO}_3][{\rm H}_2 {\rm A],}} & {k_1 = 8.3 \times 10^{ - 3} M^{ - 1} \cdot {\rm s}^{ - {\rm 1}} } \\ \end{array} $$\end{document}Bromate-bromide ion reaction: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} { - d[{\rm BrO}_3^ -]/dt = k_2 [{\rm BrO}_3][{\rm Br}^ -][{\rm H}^ +]^2,} & {k_2 = 3.6M^{ - 3} \cdot {\rm s}^{ - 1} } \\ \end{array} $$\end{document}Bromide-ascorbic acid reaction: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} { - d[{\rm Br}_{\rm 2}]/dt = k_3 [{\rm Br}_2][{\rm H}_2 {\rm A],}} & {k_3 \ge 1.7 \times 10^{ - 3} \cdot {\rm s}^{ - 1} } \\ \end{array} $$\end{document}Bromine-malonic acid reaction: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} { - d[{\rm Br}_{\rm 2}]/dt = k_4 k_4 [{\rm Br}_2][{\rm H}_2 {\rm M}]/(k_4 + k_5 [{\rm Br}_2]),} & {k_4 = 6 \times 10^{ - 3} {\rm s}^{ - 1} } \\ \end{array}, \quad {\rm }k_{ - 4} \ge 1.7 \times 10^{ - 3} \cdot {\rm s}^{ - 1} \quad {\rm }k_5 \ge 1 \times 10^7 M^{ - 1} \cdot {\rm s}^{ - 1} $$\end{document} k4 = 6 × 10-3 s-1, k-4 ≥ 1.7 × 103 s-1, k5 ≥ 1 × 107M-1 · s-1Taking into account the stoichiometry of the component reactions and using these rate equations, the concentration versus time curves of the composite system were calculated. Although the agreement is not as good as in the case of the component reactions, it is remarkable that this kinetic structure exhibits the three extrema found.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/kin.550131207
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