Why does the bleaching reaction eventually stop

When cleaning in the kitchen with a pool of bleach on tables and surfaces, there comes a time when the bleaching action seems to stop. We might say that the bleach is exhausted , and so pour out some more bleach from the bottle. 

When thinking about reaction kinetics, we need to appreciate that reactions involve chemical changes, with reactants being consumed during a reaction, and products 

Although we appreciate from Equation (8.3) that the reaction will stop when one or both of the concentration terms reaches zero, we should also appreciate that the concentration terms reach zero faster if the value of k is large, and the concentrations deplete more slowly if k is smaller. We see how the value of the rate constant is important, because it tells us how fast a reaction occurs. 

Worked Example 8.1 In solution, the cerium(IV) ion reacts with aqueous hydrogen peroxide with a 1 1 stoichiometry. The reaction has a rate constant of 1.09 x 106 dm3 mol s. How fast is the reaction that occurs between CeIV and H202, if [CeIV] = 1CT4 mol dm-3 and [H202] = 1CT3 mol dm-3  

By how fast , we are in effect asking What is the value of the rate of this reaction The reaction has a 1 1 stoichiometry so, following the model in Equation (8.3), the rate equation of reaction is 

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