Q24 of 26 Page 1

For the hydrolysis of methyl acetate in aqueous solution, the following results were obtained:


(a) Show that it follows pseudo first order reaction, as the concentration of water remains constant.


(b) Calculate the average rate of reaction between the time interval 20 to 40 seconds.


OR


(a) Define the following terms:


(i) Collision frequency


(ii) Rate constant (k)


(b) The rate constant of a first order reaction increases from 410-2 to 2410-2 when the temperature changes from 300 K to 350 K. Calculate the energy of activation (Ea). (log 2 = 0.301, log 3 = 0.4771, log 4 = 0.6021, log 6 = 0.7782)


(a) [A]1= 0.40 mol L-1 at time = 0 seconds.


[A]2 = 0.20 mol L-1 at time = 20 seconds.


The rate constant (K) for a first order reaction is given as,


K =


K =


K = 0.034 sec-1


Now, at time = 40 s, [A]2 = 0.10 mol L-1


At time = 20 s, [A]1= 0.20 mol L-1


K =


K =


K = 0.034 sec-1


Since, the value of rate constant at any time is same i.e. 0.034sec-1. Therefore, the given reaction follows pseudo first order reaction.


(b) Average rate of reaction between the time intervals 20 to 40 seconds is


= =


= 0.005 mol L-1 sec-1


OR


(a) (i) Collision frequency is the no. of collisions per second per unit volume of reaction mixture.


(ii) Rate constant (k) is a proportionality constant that indicates the relationship between the molar concentration of reactants and the rate of a chemical reaction. Greater the rate constant, faster is the rate of reaction. It is generally given as K = .


(b) Given, k1 = 410-2and k2 = 2410-2


T1 = 300 K and T2 = 350 K


We know, =


log =


Ea = 31290.64 J/mol


= 312.9064 KJ/mol


More from this chapter

All 26 →
22

How do you convert the following:

(i) Aniline to phenol


(ii) Prop-1-ene to Propan-1-ol


(iii) Anisole to 2-methoxytoluene


OR


What happens when


(i) ethanol is treated with Cu at 573 K,


(ii) phenol is treated with CH3COCl / anhydrous AlCl3,


(iii) ethyl chloride is treated with NaOCH3 ?


Write chemical equations in support of your answer.


 23

Mr. Roy, the principal of one reputed school organized a seminar in which he invited parents and principals to discuss the serious issue of diabetes and depression in students. They all resolved this issue by strictly banning junk food in schools and introducing healthy snacks and drinks like soup, lassi, milk, etc. in school canteens. They also decided to make compulsory half an hour of daily physical activities for the students in the morning assembly. After six months, Mr. Roy conducted the health survey in most of the schools and discovered a tremendous improvement in the health of the students. After reading the above passage, answer the following questions:

(i) What are the values (at least two) displayed by Mr. Roy?


(ii) As a student, how can you spread awareness about this issue?


(iii) What are tranquilizers? Give an example.


(iv) Why is use of aspartame limited to cold foods and drinks?


 25

(a) Account for the following :

(i) Bi(V) is a stronger oxidizing agent than Sb(V).


(ii) H – O – I is a weaker acid than H – O – Cl.


(iii) Bond angle decreases from H2O to H2S.


(b) Draw the structures of the following:


(i) SF4 (ii) XeF2


OR


(i) Why does PCl5 fume in moisture?


(ii) Write the name of the allotrope of sulphur which is stable at room temperature.


(iii) Chlorine water on standing loses its yellow colour. Why?


(iv) Write the disproportionation reaction of H3PO3.


(v) Complete the following equation:


F2 + H2O →


 26

Write the structures of A, B, C, D and E in the following reactions:


OR


(a) Write the structures of the main products when benzene diazonium chloride reacts with the following reagents:


(i) KI


(ii) CH3CH2OH


(iii) Cu/HCl


(b) Arrange the following in the increasing order of their basic character in an aqueous solution:


CH3NH2, (CH3)2NH, (CH3)3N


(c) Give a simple chemical test to distinguish between the following pair of compounds:


C6H5NH2 and CH3-NH2