Understanding the Chemical Oscillations
The complex kinetics diagram can be employed to understand the oscillatory behavior shown in Figure 1. At the beginning of a chemical cycle,  and  are low, as shown at 309 sec in Figure 4. Although the overall reaction is slow ( in Figure 5), reactions 5 and 6 together combine to make an autocatalytic sequence for , as follows.
 is thus increasing at an accelerating rate. The production of from , , and Ce(III) (reaction 6) is shown by the red lines surrounding in Figure 5. In turn, the red lines surrounding indicate production from , , and (reaction 5).  and  are increasing by 20% per second, as shown in the bar chart. By 325 sec,  has dramatically increased by the autocatalytic process (Figure 4). Accompanying the increase in ,  is high enough that reaction 6 is depleting Ce(III) at about 20% per second, as shown in the bar chart. Consequently, Ce(IV) is forming (Figure 4). However, a limit is being approached because the disproportionation reaction (4) limits , as indicated by the red line representing production of from . The continuing increase of [Ce(IV)] leads to the formation of via reaction 7, as shown by the 20% per second increase in  at 332 sec. At this point, the overall reaction rate has increased to . The formation of leads to the depletion of via reaction 2. This relationship is apparent in Figure 4 and in the bar chart at 332 sec in Figure 5. The red lines indicate the formation of HOBr from the reactants for reaction 2 (i.e., , , and ). The removal of shifts the system away from reactions 5, 6, and 7, as shown by the absence at 342 sec of red lines corresponding to these reactions (cf. 325 sec). [Ce(IV)] continues to fall (Figures 4 and 5), and the red lines show the accompanying production of Ce(III) and . Overall, however,  is decreasing via reactions 1 through 3. When is depleted to trace levels, the overall reaction rate is slow (viz. 360 sec in Figure 3). The low concentration of keeps reaction 2 slow while allowing to begin forming via reaction 3.  and  are again low (cf. 309 sec), and the chemical cycle then repeats.
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