Question

4)

In the table below are the absorbance – time data for the hydrolysis of p-nitrophenyl benzoate in aqueous solution. The conditions were: pH = 7.70; ionic strength,  = 0.3 M; 25 oC; initial concentration of the ester = 8 x 10-6 M; measurements at 400 nm in a 5 –cm cell. Show the mechanism of the hydrolysis of the ester, including arrows showing movement of electrons. Then, determine the first-order rate constant. You must show your work

At	t/s
0.168	0
0.218	20
0.265	40
0.303	60
0.342	80
0.402	120
0.451	160
0.488	200
0.634	¥

Answer 1

Answer:-a)

Where:- One of the R is Nitrophenyl and another R is is Benzene ring.

b)A first-order reaction is a reaction that proceeds at a rate that depends linerly on only one reactant concentaration.

We know that ln ((A)_t / (A₀)) = -kt where A_t =concentration at time t

A₀ = concentration at time 0

Here A₀₌0.168

  A_t =0.634 So, ln( 0.634 / 0.168 )= -kt

Where k is first order rate constant

By using this constant we can calculate the time here.