Sample Paper 4 for Class XII

UNIT4

CHEMICAL KINETICS                 

    M.M. 20

 

  1. A reaction is II order with respect to a reactant. How is the rate of reaction affected if the concentration of the reactant is (i) doubled (ii) reduced to half.                                                                                          1

 

  1. Calculate the half life of a first order reaction if the rate constant is 2 min. 1

 

 

  1. For a first order reaction, show that time required for 99% completion is twice the time required for the completion of 90% of reaction.                                                                                                                       2

 

  1. The following data were obtained during the first order thermal decomposition of SO2Cl2 at a constant volume SO2Cl2(g)            SO2 (g)   +   Cl2(g)                                                                                                     3
Experiment Time (S-1) Total pressure(atm)
1 0 0.5
2 100 0.6

Calculate the rat e of reaction when total pressure is 0.65 atm.

 

  1. The rate constant of a reaction at 500 K and 700 K are 0.02 S-1 and 0.07 S-1 Calculate the value of Arrhenius parameters. 3

 

  1. Explain the concept of activation energy and activated complex with the help of a diagram and example. 3

 

 

  1. The activation energy for the reaction 2HI (g)           H2 (g) + I2 (g) is 209.5 KJ/mol at 581 K. Calculate the fraction is molecules of reactants having energy equal to or greater than activation energy.                2

 

  1. Differentiate between rate of reaction and specific reaction rate. 2

 

 

  1. What is meant by Pseudo first order reaction? In a pseudo order of ester hydrolysis of ester in water, following results are obtained: 3
Time(in s) 0 30 60 90
[ester] mol/L 0.55 0.31 0.17 0.085
  • Calculate the average rate of reaction between the time intervals 30 to 60 seconds.
  • Calculate the first order pseudo rate constant.
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