Second order kinetics base-catalysed hydrolysis

In some second-order reactions the concentration of one of the reactants is many times more than the concentration of the other, so large in fact as to be considered constant throughout the reaction. In these cases, the reaction appears to follow first-order kinetics, even though, strictly speaking, it is still a second-order process. Reactions such as these are termed pseudo first-order reactions. A good example is the acid- or base-catalysed hydrolysis of an ester, in which the concentration of water is so large compared to the concentration of ester as to be considered constant. The rate of the hydrolysis appears to vary only with the concentration of the ester. 

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