Q.Acid catalysed hydrolysis of CH3COOC2H5, is monitored by taking equal amount of solution after certain interval of time and titrating it with NaOH. Following data were obtained.
Rate = K[H+][CH3COOC2H5]
Time 0 20 infinity
Vol. 20 80. 100
If [H]=0.7M Find 'K'in M-¹ s-¹.
Answers
Answer:Let, volume of Baryta water consumed at t=0=V 0 mL(It will be equivalent to the amount of acid present in definite amount of reaction mixture drawn out at regular time intervals).Let, V t = Volume of Baryta water consumed at t=tThen, (V t −V 0 )= acetic acid produced by hydrolysis of ester in time tAfter complete hydrolysis, let amount of baryta water used while titration=V∞ml⇒(V ∞ −V 0 )= acetic acid produced from complete hydrolysis of ester.Now, Initial concentration of ester= a∝(V ∞ −V 0 )Concentration of ester reacted at time "t"=x∝(V t −V 0 )Concentration of ester remaining at time "t"= (a−x)∝(V ∞ −V t )Now, for first order reaction,K= t1 ln( a−xa )= t1 ln( V ∞ −V t V ∞ −V 0 )At, t=0,V 0 =19.24 t=75 min, V t =24.20 t=∞,V ∞ =42.03Now,K= 751 ln( 42.03−24.2042.03−19.24 )= 751 ln( 17.8322.79 )⇒K= 751 ×0.25=0.0033 min −1