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

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

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

Answer 1

(i) Average rate of reaction between the time interval, 30 to 60 seconds,

= 4.67 × 10⁻³ mol L⁻¹ s⁻¹

(ii) For a pseudo first order reaction,

For t = 30 s,

= 1.911 × 10⁻² s⁻¹

For t = 60 s,

= 1.957 × 10⁻² s⁻¹

For t = 90 s,

= 2.075 × 10⁻² s⁻¹

Then, average rate constant,