Bifurcation structure in the hydrogen peroxide-sulfite system

Bifurcation structure of the hydrogen peroxide-sulfite system was examined quantitatively under the flow condition, from which rate constants k(2) and k(3) and equilibrium constant K-1 for the skeleton reactions H+ + SO32- <- > HSO3- (1); HSO3- + H2O2 --> H+ + SO42- + H2O (2); and H+ + HSO3- + H2O2 - -> 2H(+) + SO42- H2O (3) were determined at 13.2, 20.0, 25.0, and 32.0 degr ees C. The results are summarized as k(2) (M(-1)s(-1)) = (1.19 x 10(6))exp( -Delta H(2)double dagger/RT), Delta H(2)double dagger = 28.2 kJ.M-1; k(3) ( M(-2)s(-1)) = (5.93 x 10(9))exp(-Delta H(3)double dagger/RT), Delta H(3)dou ble dagger = 18.7 kJ.M-1; K-1 (M-1) = (1.8 x 10(6))exp(-Delta H-1/RT), Delt a H-1 = 7.4 kJ.M-1. The system is well known to exhibit chemical oscillatio ns in its pH value when it is combined with an appropriate species that pro vides a negative feedback channel. However, the role of the nonlinearity in herent in this subsystem has not been clarified sufficiently under the flow condition. In the present work, we proposed an approximate analytical meth od to analyze the complicated equations representing the bifurcation struct ure and succeeded in determining the above constants and their temperature dependence. The present results are expected to be useful in designing a ne w chemical oscillator system by coupling this subsystem with appropriate ne gative-feedback species. In addition, the information given here for the te mperature dependence would be useful to design the temperature-insensitive chemical oscillator system which is interested recently in relation to the function in living systems.