Kinetics of the Reaction for Generation of Chlorine Dioxide from Sodium Chlorate and Hydrochloric Acid

Based on the mechanism of ClO3-/Cl- reaction system, the kinetics for reaction of sodium chlorate and hydrochloric acid to generate ClO2 was studied. The rate equation of this reaction system was deduced and simplified as a formula with mixed-order (combination of first-order and second-order) towards ClO3-. This rate formula indicates that the initial rate of the reaction is the first-order with respect to ClO3-, and the reaction rate is the second-order with respect to ClO3- when [ClO3-] becomes close to zero. The rate constants of the first-order were determined as 0.0168s-1(30°C), 0.0221s-1(40°C), and 0.0279s-1(50°C), respectively, and that of the second-order were obtained for 0.0019L·mol-1·s-1(30°C), 0.0028L·mol-1·s-1(40°C), and 0.0060L·mol-1·s-1(50°C), respectively. The results of statistic test prove that the rate formula obtained in this work is credible.