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

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

(i)Calculate the average rate of reaction between the time intervals 30 to 60 seconds.
(ii)Calculate the pseudo first order rate constant for the hydrolysis of ester.
Answer
(i)
For average rate of reaction use formula

Plug the value in this formula we get
r_avg = (0.31 – 0.17 ) / (60 – 30 ) = 0.14 / 30 = 4.67 × 10⁻³ mol L⁻¹ s⁻¹
(ii)
Formula for a pseudo first order reaction,

We can use any time interval
Plug the values for interval 0 sec to 30 sec, we get

After calculation we get
k = 1.911 × 10⁻² s⁻¹