# 12th Chemistry Important Questions Unit 7 Chemical Kinetics

TN 12th Chemistry Important Questions Unit 7 Chemical Kinetics. 12th Chemistry Important Questions Chapter 7 Transition And Inner Transition Elements +2 Chemistry Important 2 Marks, 12th Chemistry Important 3 Marks, Chemistry Important 5 Marks Questions Based on reduced Syllabus 2021-2022. 12th Free Online Test (MCQs). HSC 12th Chemistry Revision Test Important Questions. 12th Tamil Full Guide.

## 12th Chemistry Important Questions

## Unit 7 Chemical Kinetics

### 12th Chemistry All Units Important Questions

- 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 –> product.
- 4. Define the half-life of a reaction. Show that for a first-order reaction half-life is independent of initial concentration.
- 5. What is an elementary reaction? Give the differences between the order and molecularity of a reaction.
- 6. 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 Br_{2}. - 7. 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 1/3 and concentration of [L] is quadrupled. - 8. The rate of formation of a dimer in a second order reaction is 7.5×10
^{-3}molL^{-1}s^{-1}at 0.05 mol L^{-1}monomer concentration. Calculate the rate constant. - 9. Write the Arrhenius equation and explain the terms involved.
- 10. The decomposition of Cl2O7 at 500K in the gas phase to Cl
_{2}and O_{2}is a first order reaction. After

1 minute at 500K, the pressure of Cl_{2}O_{2}falls from 0.08 to 0.04 atm. Calculate the rate constant in s^{-1}. - 11. Hydrolysis of methyl acetate in aqueous solution has been studied by titrating the liberated acetic acid against sodium hydroxide. The concentration of an ester at different temperatures is given below.
- 12. Explain pseudo first order reaction with an example.
- 13. Identify the order for the following reactions

(i) Rusting of Iron

(ii) Radioactive disintegration of_{92}U^{238}

(iii) 2A + 3B –>AB products ; rate =k[A]^{1/2}[B]^{2} - 14. A gas phase reaction has energy of activation 200 kJ mol-1. If the frequency factor of the reaction is 1.6 x 10
^{13}s^{-1}Calculate the rate constant at 600 K. (e^{-40.09}=3.8×10^{-18}) - 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 SO
_{2}Cl_{2}–>SO_{2}+ Cl_{2}which obeys first order kinetics is 8.0 minutes. How long will it take for the concentration of SO_{2}Cl_{2}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 180seconds?
- 18. A zero order reaction is 20% complete in 20 minutes. Calculate the value of the rate constant. In what time will the reaction be 80%complete?
- 19. The activation energy of a reaction is 225 k Cal mol
^{-1}and the value of rate constant at 40°C is 1.8×10^{-5}s^{-1}Calculate the frequency factor,A. - 20. 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?
- 21. Define the rate of the reaction.
- 22. Write the rate expression of the following reaction 2NH
_{3}–> N_{2}+ 3H_{2} - 23. What are the differences between rate and rate constant of a reaction?
- 24. What are the differences between order and molecularity?
- 25. Give the two examples of first order reaction
- 26. Define Zero order reaction?
- 27. Derive the relationship between half life period and zero order rate constant
- 28. Derive the rate constant for Zero order reaction
- 29. Derive the rate constant for First order reaction
- 30. Derive the relationship between half life period and First order rate constant
- 31. Define half life period
- 32. Define Activation energy
- 33. 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.
- 34. Why a negative sign is introduced in the rate expression?
- 35. Give two examples for Zero order reaction.
- 36. Derive Arhenius equation to calculate activation energy from the rate constant K
_{1}and K_{2}at temperature T_{21}and T_{2}respectively.