Question

In a reaction, 5 g ethyl acetate is hydrolysed per litre in the presence of dil. HCl in 300 min. If the reaction is of first order, and the initial concentration of ethyl acetate is 22 g/L, then calculate the rate constant of the reaction.

Answer 1

Given:

Reaction: Hydrolysis of ethyl acetate (a first-order reaction)

Initial concentration [A]₀ = 22 g/L

Amount hydrolyzed in 300 min = 5 g

So, final concentration [A] = 22 − 5 = 17 g/L

Time t = 300 min

By using the first-order rate constant formula:

`k = 2.303/t log ([A]_0/([A]))`

`k = 2.303/300 log (22/17)`

= `2.303/3000 log 1.294`

= `(2.303 xx 0.1116)/300`    ...(log 1.294 = 0.1116)

= `0.2572/300`

k = 8.57 × 10⁻⁴ min⁻¹