1. The problem statement, all variables and given/known data Why is the acid based catalysed reaction of esters first order while the akaline based catalysed reaction is second order. 2. Relevant equations rate is proportional to [ester]^a [water]^b 3. The attempt at a solution i know that a fisrt order is proportional to only one substance, here it is the ester. and most probably the second order is proportional to both the ester and the OH-. now i can't explain why.