Determination of rate of reaction and rate constant of the hydrolysis of ester (ethyl acetate) with alkali(sodium hydroxide)

Abstract

The rate of reaction is defined as the change in the number of molecules of reacting species per unit volume per unit time. Hydrolysis is the decomposition reaction involving breaking of a bond and the addition of water elements. In this hydrolysis of ethyl acetate with sodium hydroxide, hydrochloric acid was used as catalyst to accelerate the reaction mixture. 1ml and 2ml of ethyl acetate was injected separately into the 500 ml conical flask which contains 0.05N of sodium hydroxide and thoroughly mixed. At regular time interval, 0, 10, 20, 30, 40, and 90 minutes, 25ml of each of the samples were withdrawn into a 250 ml conical flask containing 0.05N hydrochloric acid, and titrated against 0.05N sodium hydroxide solution using phenolphthalein as an indicator. From the value of sodium hydroxide, the hydrolysis involving the 1ml ethyl acetate was faster than that of the 2ml ethyl acetate, indicating that the higher the concentration the faster the rate of reaction. The rate constant after calculation from the graphs was approximately 0.003mincmfor the 1ml and 2ml of ethyl acetate, signifying that while the rate of reaction is concentration dependent but the rate constant is notconcentration dependent.