Question

In a pseudo first order hydrolysis of ester in water, the following results were obtained:

t/s	0	30	60	90
(Ester)/mol L-1	0.55	0.31	0.17	0.085

(a) Calculate the average rate of reaction between the time interval 30 to 60 seconds.

(b) Calculate the pseudo first order rate constant for the hydrolysis of ester.

Answer 1

(a) Average rate during the time interval 30-60 seconds

Average rate

\(= \frac{C_2 -C_1}{t_2 -t_1}\)

\(= \frac{0.17 - 0.31}{60-30}\)

\(= \frac{-0.14}{30}\)

= – 4.67 × 10^-3

= mol L^-1 s^-1

(b) Pseudo first order rate constant

Here the value of rate constant is 1.98 × 10^-2s^-1.