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Chemical Kinetics 3 Mark Book Back Question Paper With Answer Key

12th Standard

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Chemistry

Time : 01:30:00 Hrs
Total Marks : 72

     3 Marks 

    24 x 3 = 72
  1. Define average rate and instantaneous rate.

  2. Define rate law and rate constant.

  3. Derive integrated rate law for a zero order reaction A\(\longrightarrow \) product.

  4. Define half life of a reaction. Show that for a first order reaction half life is independent of initial concentration.

  5. Explain the rate determining step with an example.

  6. Describe the graphical representation of first order reaction.

  7. Write the rate law for the following reactions.
    (a) A reaction that is 3/2 order in x and zero order in y.
    (b) A reaction that is second order in NO and first order in Br2.

  8. The rate law for a reaction of A, B and C has been found to be rate = k[A]2[B][L]3/2 How would the rate of reaction change when
    (i) Concentration of [L] is quadrupled
    (ii) Concentration of both [A] and [B] are doubled
    (iii) Concentration of [A] is halved
    (iv) Concentration of [A] is reduced to \(\left(\frac{1}{3}\right)\) and concentration of [L] is quadrupled.

  9. The rate of formation of a dimer in a second order reaction is 7.5 x 10-3 mol L-1 s-1 at 0.05 mol L-1 monomer concentration. Calculate the rate constant.

  10. For a reaction x + y + z\(\longrightarrow \) products the rate law is given by rate =k[x]3/2[y]1/2. What is the overall order of the reaction and what is the order of the reaction with respect to z.

  11. Explain pseudo first order reaction with an example.

  12. Identify the order for the following reactions
    (i) Rusting of Iron
    (ii) Radioactive disintegration of 92U238
    (iii) 2A+3B⟶ products ;rate = k[A]1/2[B]2

  13. How do concentrations of the reactant influence the rate of reaction?

  14. How do nature of the reactant influence rate of reaction.

  15. The rate constant for a first order reaction is 1.54 x 10-3 s-1. Calculate its half life time.

  16. The half life of the homogeneous gaseous reaction SO2Cl2 → SO2 + Cl2 which obeys first order kinetics is 8.0 minutes. How long will it take for the concentration of SO2Cl2 to be reduced to 1% of the initial value?

  17. The time for half change in a first order decomposition of a substance A is 60 seconds. Calculate the rate constant. How much of A will be left after 180 seconds?

  18. Benzene diazonium chloride in aqueous solution decomposes according to the equation \({ C }_{ 6 }{ H }_{ 5 }{ N }_{ 2 }Cl\longrightarrow { C }_{ 6 }{ H }_{ 5 }Cl+{ N }_{ 2 }\)Starting with an initial concentration of 10g L-1, the volume of N2 gas obtained at 50 °C at different intervals of time was found to be as under:

    t(min) 6 12 18 24 30 \(\infty \)
    Vol of N2 (ml) 19.3 32.6 41.3 46.5 50.4 58.3

    Show that the above reaction follows the first order kinetics. What is the value of the rate constant?

  19. A first order reaction is 40% complete in 50 minutes. Calculate the value of the rate constant. In what time will the reaction be 80% complete?

  20. A first order reaction takes 8 hours for 90% completion. Calculate the time required for 80% completion. (log 5 = 0.6989 ; log10 = 1)

  21. The half life of a first order reaction x →products is 6.932 x 104 s at 500K. What percentage of x would be decomposed on heating at 500K for 100 min. (e0.06 = 1.06).

  22. Show that in case of first order reaction, the time required for 99.9% completion is nearly ten times the time required for half completion of the reaction.

  23. The rate constant of a reaction at 400 and 200K are 0.04 and 0.02 s-1 respectively. Calculate the value of activation energy.

  24. Give two exapmles for zero order reaction.

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