Why is ester hydrolysis slow in the beginning and becomes faster after some time?

Answer

In hydrolysis of ethyl acetate, acetic acid and ethyl alcohol are formed. The reaction is initially very slow but gradually its rate increases. This is due to the formation of acetic acid which as an auto-catalyst in this reaction.
`CH_(3)COOC_(2)H_(5)+H_(2)O rarr CH_(3)COOH+C_(2)H_(5)OH`
`(##RES_PHY_CHM_XII_V02_C03_E01_018_A01##)`
In the case of homogeneous auto-catalytic reactions, rate increases with passage of time because in such cases rate of reaction is directly proportional to concentration of catalyst. e.g.,
Rate `=underset("Reactant")(k[CH_(3)COOC_(2)H_(5)])underset("Catalyst")([CH_(3)COOH])`