Journal of the Brazilian Chemical Society
Print version ISSN 0103-5053
SANT'ANNA, Rafaela T. P. et al. Kinetics and mechanism of chlorate-chloride reaction. J. Braz. Chem. Soc. [online]. 2012, vol.23, n.8, pp.1543-1550. Epub Aug 16, 2012. ISSN 0103-5053. http://dx.doi.org/10.1590/S0103-50532012005000017.
The kinetics of chlorate-chloride reaction was studied following the formation of ClO2• by UV-Vis spectroscopy. For comparison with other results in the literature, the initial rate was measured after small induction period. The results show a special effect of a saturation profile for the initial chloride concentration, suggesting the formation of the intermediate Cl2O32-. At low chloride concentration, the reaction orders for chlorate, chloride and H+ were 1.03 ± 0.05, 1.02 ± 0.03 and 2.80 ± 0.03, respectively. These order values must be considered with care because they were calculated using the maximum rate values after induction period. In fact, the presence of this induction period indicates that the system is complex. Then, a mechanism was proposed to explain the experimental results, and includes the reaction between two ClOClO to form ClO2•. It was able to model the experimental curves at different [H+]0 and at low and high [Cl-]0.
Keywords : chlorate; kinetics; mechanism.