Investigation Of Chemical Oscillatory Reaction System Related To Sodium Chlorite-potassium Iodide

In recent years, chemical oscillatory reaction has gained extensive attention of researchers. The major research interest is focus on the design of new oscillator, the properties of oscillatory system, the oscillation mechanism and the application in analytical determination. This paper investigated the NaClO2-KI-acetylacetone (AA) and NaClO2-KI-allyl acetoacetate (AAA) chemical oscillatory reaction systems by UV-Vis spectrophotometric method, and explored the related properties of oscillatory system.In the system of NaClO2-KI-AA, the oscillation phenomenon can be observed at 297 nm and 351 nm without adding starch and 570 nm with adding starch. The initial concentration of reactants had a great influence on the oscillation reaction. Taking 297 nm as an example, the amplitude and the period of oscillation increase as the initial concentration of KI and AA increase. The amplitude decreases, the period of oscillation shortens, and the number of oscillation waves increases as the initial concentration of NaClO2 increases. The equations of the amplitude and the period of oscillation changing with initial concentrations of various substances were obtained by Origin software curve fitting of the oscillatory curves obtained under different initial concentration. Obvious oscillation curve can appear in a certain range of initial concentrations of sodium chlorite and potassium iodide by keeping the molar ratio of [KI]0/[NaClO2]0 constant and changing the initial concentrations of sodium chlorite and potassium iodide at the same time. The pH value also influences the oscillatory system. The oscillation reaction can occur at a certain range of pH values. The induction time of oscillation reaction is reduced, the life time of oscillation reaction is also reduced with the increase of reaction temperature. The oscillation reaction can be accelerated by increasing the reaction temperature. The relationship of induction time and the oscillation period with reaction temperature was summarized according to Arrhenius equation. Their apparent activation energies were also obtained.This paper also investigated the system of NaClO2-KI-AAA, the influence of the initial concentrations of various substances, pH values and reaction temperature on the oscillation reaction was also studied. The oscillation phenomenon can be observed at 360 nm and 585 nm with adding starch. The equations of the amplitude and the period of oscillation changing with initial concentrations of various substances were obtained by Origin software curve fitting of the oscillatory curves obtained under different initial concentration. Obvious oscillation curve can appear in a certain range of initial concentrations of sodium chlorite and potassium iodide by keeping the molar ratio of [KI]o/[NaClO2]o constant and changing the initial concentrations of sodium chlorite and potassium iodide at the same time. The pH value also influences the oscillatory system. The oscillation reaction can occur at a certain range of pH values. The induction time of oscillation reaction is reduced, the life time of oscillation reaction is also reduced with the increase of reaction temperature. The oscillation reaction can be accelerated by increasing the reaction temperature. The relationship of the oscillation period and the induction time with reaction temperature was summarized according to Arrhenius equation. Their apparent activation energies were also obtained.This paper also investigated the kinetic of AAA-I2 reaction. The influence of r (r =[AAA]o/[I2]o) on the reaction was studied. The reaction becomes slowly with the increase of molar ratio. The influence of pH value on the reaction was studied at the molar ratio r 5.199. The reaction rate equation was obtained. The equation of the apparent reaction order for hydrogen ion changing with pH value was also obtained.