An acid catalysed hydrolysis of ester is carried out in presence of HCl. Small but same volume of samples were taken out at various instant and were titrated with standardised solution of NaOH and following data was obtained
t=O t = 120 sec. $t = \infty$
$V_{NaOH}$ required for neutralisation 20 ml 55ml 60ml
If initially 6 M of ester was taken then calculate abed, where ab
$a b = t_{1 / 2}$ of the hydrolysis of ester
cd = Molar concentration of HCl taken in the experiment.

Question

An acid catalysed hydrolysis of ester is carried out in presence of HCl. Small but same volume of samples were taken out at various instant and were titrated with standardised solution of NaOH and following data was obtained
t=O t = 120 sec. $t = \infty$
$V_{NaOH}$ required for neutralisation 20 ml 55ml 60ml
If initially 6 M of ester was taken then calculate abed, where ab
$a b = t_{1 / 2}$ of the hydrolysis of ester
cd = Molar concentration of HCl taken in the experiment.

Infinity Learn · Accepted Answer

Initially, at t = 0, m mol of HCl = 20 x N, where (N = normality of NaOH) at t = ∞, m mol of HCl + m mol of acid formed = 60 x N ⇒ m mol of acid formed = 60 x N - 20 x N = 40 N ⇒ m mol of ester taken =40N∝aAt t == 120 sec, m mol of acid formed =55×N−20×N=35N∝xa−x∝5Nk×t=ln⁡aa−xk×120=ln⁡40N5Nk×120=3ln⁡2t1/2=40Also, N1v1=N2v26×v1=40×NFor HCl,N′×v1=20×N=3v1⇒N′=3

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	t=O	t = 120 sec.	$t = \infty$
$V_{NaOH}$ required for neutralisation	20 ml	55ml	60ml