Question

Which observable property is used in the kinetic study of the following first order reaction and why?

\[\ce{CH3COOC2H5 + H2O ->[H+] CH3COOH + C2H5OH}\]

Answer 1

1. In the kinetic study of the acid-catalysed hydrolysis of ethyl acetate \[\ce{CH3COOC2H5 + H2O ->[H+] CH3COOH + C2H5OH}\] volume of alkali required to neutralise the acetic acid formed is the observable property used.
2. During the reaction, acetic acid (CH₃COOH) is formed as a product.
3. The concentration of acetic acid increases with time.
4. At various time intervals, small samples of the reaction mixture are withdrawn and titrated against standard alkali (NaOH).
5. Since the amount of alkali required is directly proportional to the amount of CH₃COOH formed, it reflects the progress of the reaction.
6. This makes it possible to apply the first-order rate equation\[\ce{k = \frac{2.303}{t} log_10 (\frac{V_\infty - V_0}{V_\infty - V_1})}\]This confirms the first-order nature of the reaction with respect to the ester.