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Chemistry Class by Satyaveer Singh Sisodiya (M.Sc.(Chem.) B.Ed M.A.

(Eng)Ph.No.9719511626
Chap-4, chemical kinetics Class-12 Dpp Questions
(Chemistry)

1. Define the term chemical kinetics?

2. Define – Rate of reaction?
3. What is average rate of a reaction? How is it determined?
4. What are the units of rate of a reaction?
5. What is instantaneous rate of a reaction? How is it determined?
6. For the following reactions, write the rate of reaction expression in terms of
reactants and products?
i) 4NH3 (g) + 5O2 (g) 4NO (g) + 6H2O (g) ii) 2N2O5 2NO2 + O2
7. For the chemical decomposition of SO2Cl2, its initial concentration is 0.8420 mol/L
and final concentration is 0.215 molL-1 in 2 hours. What is the average rate of this
reaction?
8. In the expression of rate of reaction in terms of reactants, what is the significance
of negative sign?
9. For the reaction 2O3 (g) 3O2 (g), -∆[O3]/∆t was found to be 5.0 X 10-4 atm/s.
Determine the value of -∆[O2]/∆t in atm/s during this period of time?
10. A chemical reaction 2A 4B+C in gas phase occurs in a closed vessel. The
concentration of B is found to be increased by 5 X 10-3 mole L-1 in 10 second.
Calculate
(i) the rate of appearance of B (ii) the rate of disappearance of A?
(iii)Is rate of reaction always constant?
11. Define rate law .
12. Enlist the factors affecting rate of a reaction?
13. What do you understand by rate law expression?
14. Is it possible to determine or predict the rate law theoretically by merely Looking
at the equation?
15. Define the terms –
i) Order of a reaction ii) Molecularity of a reaction
16. What are elementary and complex reactions?
17. Differentiate between order and molecularity of a reaction?
18. Determine the overall order of a reaction which has the rate law R = K [A]5/2 [B]3/2
19. What are the units of a rate constant of a
a) First order reaction b) nth order reaction.
20. For the reaction A+B C+D, the rate of reaction doubles when the
concentration of A doubles, provided the concentration of B is constant. To what
order does A enter into the rate expression?
21.Identify the reaction order for from each of the following rate constant –
a) k = 2.3 ×10-5 L mol-1 s-1 b) k = 3.1 × 10-4 s-1

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Chemistry Class by Satyaveer Singh Sisodiya (M.Sc.(Chem.) B.Ed M.A.
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Chap-4, chemical kinetics Class-12 Dpp Questions
(Chemistry)

22. Consider the equation 2 NO (aq) + 2H2 (g) N2 (g) + 2H2O (g) The rate law
for this equation is first order with respect to H2 and second order with respect to
NO. write the rate law for this reaction.
23. The rate Law for the reaction A+B C is rate = K [A] 2 [B] . What would the
reaction rate be when concentration of both A and B are doubled?
24. Write the integrated rate equation for –
i) zero order reaction. ii) first order reaction.
25. From the graph below

log R
K
2.303
= - Slope

T
i) Identify the order of reaction.
ii) What will be the unit of rate constant?
26. The reaction 2N2O5 (g) 2NO2 (g) +O2 (g) was studied and the following
data were collected :
S.No [N2O5] mol L-1 Rate of disappearance of [N2O5](mol/L/min)
-2
1. 1.13×10 34×10-5
2. 0.84 ×10-2 25×10-5
3. 0.62×10-2 18×10-5
Determine i) The order ii) The rate law. iii) Rate constant for the reaction.
27. The following experimental data was collected for the reaction:
Cl2 (g) + 2NO (g) 2 NOCl(g)
Serial Intial conc. Of Cl2 (mol/L) [NO] mol/L Initial Rate,(mol/L/s)
1 0.10 0.010 1.2 X 10-4
2 0.10 0.030 10.8 X 10-4
3 0.20 0.030 21.6 X 10-4
Construct the rate equation for the reaction.
28. Draw a graph for
a) Concentration of reactant against time for a zero order reaction.
b) Log [Ro]/ [R] against time for a first order reaction.
29. What is the use of integrated rate equation?
30. For first order reaction – A B
Write (1) Differential rate law. (2) Integrated rate law.
Unit –I H. No. 200 sec-6c near kaila devi chauraha sikandra Agra,
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Chemistry Class by Satyaveer Singh Sisodiya (M.Sc.(Chem.) B.Ed M.A.
(Eng)Ph.No.9719511626
Chap-4, chemical kinetics Class-12 Dpp Questions
(Chemistry)

31. Give an example of pseudo – first order reaction ?

32. Write the expression for half – life period of a first order reaction?
33. A first order reaction is found to have a rate constant K = 5.5 × 10-14 sec -1. Find
half life of reaction?
34. The time required to decompose SO2Cl2 to half of its initial amount is 60 min. If
the decomposition is a first order reaction, calculate the rate constant of the
reaction?
35. The rate constant for the first order decomposition of N2O5 at 250C is 3X10-2 min-1.
It the initial concentration of N2O5 is 2X10-3 mol/L, How long will it take to drop the
concentration to 5X10-4 mol /L ?
36. Write Arrhenius equation.
37. If the activation energy of a reaction is zero, will the rate of reaction still depend
on temperature?
38. In general it is observed that the rate of a chemical reaction doubles with every
10 0C rise in temperature. If this generalization holds for a reaction in the
temperature range295K to 305K, what would be the activation energy for this
reaction? (R=8.314Jk-1 mol-1)
39. The rate constant for a reaction is 1.5× 107 s-1 at 500C and 4.5× 107 s-1at 1000C.
Calculate the value of activation energy for the reaction R=8.314 JK-1 mol-1?
40. Plot a graph showing variation of potential energy with reaction .coordinate?
41. What is the effect of catalyst on rate constant?
42. How is activation energy affected on adding a catalyst?
43. What do you mean by the term- collision frequency?
44. How does collision theory explain formation of products in a chemical reaction?
45. What is the drawback of collision theory?
46. How does the number of collisions change on increasing the temperature?
47. There is no bar on the no. of collisions among the reaching species. Why most of
the reactions do not take place under normal conditions?
48. From the fig. (1)

Unit –I H. No. 200 sec-6c near kaila devi chauraha sikandra Agra,
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Chemistry Class by Satyaveer Singh Sisodiya (M.Sc.(Chem.) B.Ed M.A.
(Eng)Ph.No.9719511626
Chap-4, chemical kinetics Class-12 Dpp Questions
(Chemistry)

(a) Calculate ∆rE for the reaction, activation energy for forward reaction.
(b) Identify the curve for catalysed reaction.
(c) what is the energy of activation in the presence of catalyst?
49. The activation energy of reaction is 75.2 KJ/mol in the absence of a catalyst and
50.14 KJ/Mol in the presence of a catalyst. How many times will the reaction grow
in the presence of a catalyst, if the reaction proceeds at 250C?
50. The rate of a particular reaction quadruples when the temperature changes from
293 K to 313 K. Calculate activation energy for such a reaction.
NCERT QUESTION
Q.2 The decomposition of N2O5 in CCl4 at 318K has been studied by monitoring the
concentration of N2O5 in the solution. Initially the concentration of N2O5 is 2.33 mol
L–1 and after 184 minutes, it is reduced to 2.08 mol L–1. The reaction takes place
according to the equation; 2 N2O5 (g) 4 NO2 (g) + O2 (g). Calculate the
average rate of this reaction in terms of hours, minutes and seconds. What is the
rate of production of NO2 during this period?(Ans. = 2.72 × 10–3 mol L–1min–1)
Q.3 For the reaction R P, the concentration of a reactant changes from 0.03M to
0.02M in 25 minutes. Calculate the average rate of reaction using units of time
both in minutes and seconds.(Ans. = 6.66 x 10-6 M / sec)
Q.4 In a reaction, 2A Products, the concentration of A decreases from 0.5 mol L –1
to 0.4 mol L–1 in 10 minutes. Calculate the rate during this interval?(Ans. = 0.005
mol-1 L-1 min-1)
Q.5 Calculate the overall order of a reaction which has the rate expression
(a) Rate = k [A]1/2 [B]3/2 (b) Rate = k [A]3/2 [B]–1
Q.6 Identify the reaction order from each of the following rate constants.
(i) k = 2.3 × 10–5 L mol–1 s–1 (ii) k = 3 × 10–4 s–1
Q.7 For a reaction, A + B Product; the rate law is given by, r = k [A]1/2 [B]2. What
is the order of the reaction?
Unit –I H. No. 200 sec-6c near kaila devi chauraha sikandra Agra,
Unit- II 511, awadhpuri near SBI shahganj Agra, ph-9719511626
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Chemistry Class by Satyaveer Singh Sisodiya (M.Sc.(Chem.) B.Ed M.A.
(Eng)Ph.No.9719511626
Chap-4, chemical kinetics Class-12 Dpp Questions
(Chemistry)

Q.8 The conversion of molecules X to Y follows second order kinetics. If

concentration of X is increased to three times how will it affect the rate of formation
of Y ?
Q.9 The initial concentration of N2O5 in the following first order reaction N2O5(g)
2NO2(g) + ½ O2 (g) was 1.24 × 10–2 mol L–1 at 318 K. The concentration of N2O5
after 60 minutes was 0.20 × 10–2 mol L–1.Calculate the rate constant of the reaction
at 318 K. (Ans. ; k = 0.0304 min-1)
Q.10 The following data were obtained during the first order thermal decomposition
of N2O5 (g) at constant volume: 2N2 O5(g) 2N2 O4(g) + O2 g
S.No. Time/s Total Pressure/(atm)
1. 0 0.5
2. 100 0.512
-1
Calculate the rate constant.(Ans.; k= 4.98 10 s )
Q.11 A first order reaction is found to have a rate constant, k = 5.5 × 10-14 s-1. Find
the half-life of the reaction.(Ans. = 1.26 × 1014 s)
Q.12. Show that in a first order reaction, time required for completion of 99.9% is 10
times of half-life (t1/2) of the reaction.
(Ans. = 10)
Q.13 Hydrolysis of methyl acetate in aqueous solution has been studied by titrating
the liberated acetic acid against sodium hydroxide. The concentration of the ester
at different times is given below.
t/min 0 30 60 90
–1
C/mol L 0.8500 0.8004 0.7538 0.7096
Show that it follows a pseudo first order reaction, as the concentration of water
remains nearly constant (55 mol L–1), during the course of the reaction. What is the
value of k′ in this equation? Rate = k′ [CH3COOCH3][H2O]
(Ans k = 3.64 × 10–5 mol–1 L min–1)
Q14 A first order reaction has a rate constant 1.15 × 10-3 s-1. How long will 5 g of this
reactant take to reduce to 3 g? (Ans. 444.27 sec).
Q.15 Time required to decompose SO2Cl2 to half of its initial amount is 60 minutes. If
the decomposition is a first order reaction, calculate the rate constant of the
reaction.(Ans. 0.0115 /min)
Q.16 The rate constants of a reaction at 500K and 700K are 0.02s–1 and 0.07s–1
respectively. Calculate the values of Ea and A. (Ans. = 1.61)
Q.17 The first order rate constant for the decomposition of ethyl iodide by the
reaction C2H5I(g) → C2H4 (g) + HI(g) at 600K is 1.60 × 10–5 s–1. Its energy of
activation is 209 kJ/mol. Calculate the rate constant of the reaction at 700K.
(Ans .k2 = 6.36 × 10–3 s–1)
Unit –I H. No. 200 sec-6c near kaila devi chauraha sikandra Agra,
Unit- II 511, awadhpuri near SBI shahganj Agra, ph-9719511626
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Chemistry Class by Satyaveer Singh Sisodiya (M.Sc.(Chem.) B.Ed M.A.
(Eng)Ph.No.9719511626
Chap-4, chemical kinetics Class-12 Dpp Questions
(Chemistry)

Q.18 What will be the effect of temperature on rate constant ?

Q.19 The rate of the chemical reaction doubles for an increase of 10K in absolute
temperature from 298K. Calculate Ea.(Ans. 52.897 kj)
Q.20 The activation energy for the reaction 2 HI(g) H2 + I2 (g) is 209.5 kJ
–1
mol at 581K.Calculate the fraction of molecules of reactants having energy equal
to or greater than activation energy?(Ans. 1.47 x 10-19)
Q.21 From the rate expression for the following reactions, determine their order of
reaction and the dimensions of the rate constants.
(i)3NO(g) N2O (g)Rate = k[NO]2
(ii) H2O2 (aq) + 3I– (aq) + 2H+ 2H2O (l) + 3 I− Rate = k[H2O2][I-]
(iii) CH3CHO(g) CH4(g)+CO(g) Rate =k[CH3CHO]3/2
(iv) C2H5Cl(g) C2H4(g)+HCl(g) Rate = k [C2H5Cl]
Q.22 For the reaction: 2A + B A 2B
2 –6 –2 2 –1
the rate = k[A][B] with k = 2.0 × 10 mol L s . Calculate the initial rate of the
reaction when [A] = 0.1 mol L–1, [B] = 0.2 mol L–1. Calculate the rate of reaction
after [A] is reduced to 0.06 mol L–1. (Ans. rate=3.89x10-9 mol/Ls)
Q.23 The decomposition of NH3 on platinum surface is zero order reaction. What are
the rates of production of N2 and H2 if k = 2.5 × 10–4 mol–1 L s–1?
(Ans. =2.5x10-4 mol/L sec,7.5x10-4 mol/L sec)
Q.24 The decomposition of dimethyl ether leads to the formation of CH4, H2 and CO
and the reaction rate is given by
Rate = k [CH3OCH3]3/2 The rate of reaction is followed by increase in pressure in a
closed vessel, so the rate can also be expressed in terms of the partial pressure of
dimethyl ether, i.e., Rate = k [CH3OCH3] 3/2 . If the pressure is measured in bar and
time in minutes, then what are the units of rate and rate constants?
Q.25 Mention the factors that affect the rate of a chemical reaction.
Q.26 A reaction is second 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 ?
Q.27What is the effect of temperature on the rate constant of a reaction? How can
this temperature effect on rate constant be represented quantitatively?
Q.28 In a pseudo first order hydrolysis of ester in water, the following results were
obtained:
t/s 0 30 60 90
–1
[Ester]/mol L 0.55 0.31 0.17 0.085
(i) Calculate the average rate of reaction between the time interval 30 to 60
seconds.
(ii) Calculate the pseudo first order rate constant for the hydrolysis of ester.
(Ans.rate=4.67x10-3 mol /Lsec k=1.98x10-2 /sec)
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Chemistry Class by Satyaveer Singh Sisodiya (M.Sc.(Chem.) B.Ed M.A.
(Eng)Ph.No.9719511626
Chap-4, chemical kinetics Class-12 Dpp Questions
(Chemistry)

Q.29 A reaction is first order in A and second order in B.

(i) Write the differential rate equation. (ii) How is the rate affected on increasing
the concentration of B three times? (iii) How is the rate affected when the
concentrations of both A and B are doubled?
Q.30 In a reaction between A and B, the initial rate of reaction (R0) was measured for
different initial concentrations of A and B as given below:
A/ mol L–1 0.20 0.20 0.40
–1
B/ mol L 0.30 0.10 0.05
–1 –1 –5 –5
r/mol L s 5.07×10 5.07×10 1.43×10–4
What is the order of the reaction with respect to A and B?
Q.31 The following results have been obtained during the kinetic studies of the
reaction:
2A + B → C + D
Exp. [A]/mol L–1 [B]/mol L–1 Initial rate D/mol L–1 min–1
I 0.1 0.1 6.0 × 10 –3
II 0.3 0.2 7.2 × 10 –2
III 0.3 0.4 2.88 × 10 –1
IV 0.4 0.1 2.40 × 10 –2
Determine the rate law and the rate constant for the reaction.
(Ans.=3,k= 6 L2 mol-2 min)
Q.32 The reaction between A and B is first order with respect to A and zero order
with respect to B. Fill in the blanks in the following table:
Exp. [A]/ mol L–1 [B]/ mol L–1 Initial rate/mol L–1 min–1
I 0.1 0.1 2.0 × 10 –2
II - 0.2 4.0 × 10 –2
III 0.4 0.4 –
IV – 0.2 2.0 × 10 –2
Q.33 Calculate the half-life of a first order reaction from their rate constants given
below:
(i) 200 s–1 (ii) 2 min–1 (iii) 4 years–1 (Ans. =3.465x10-3sec,0.3465 min,0.1732 yr)
Q.34 The half-life for radioactive decay of 14C is 5730 years. An archaeological
artifact containing wood had only 80% of the 14C found in a living tree.Estimate
the age of the sample. (Ans. = 1845yrs)
Q.35 The rate constant for a first order reaction is 60 s–1. How much time will it take
to reduce the initial concentration of the reactant to its 1/16th value?
(Ans. =0.0462 sec)
Q.36 During nuclear explosion, one of the products is 90Sr with half-life of 28.1
years. If 1μg of 90Sr was absorbed in the bones of a newly born baby instead of
Unit –I H. No. 200 sec-6c near kaila devi chauraha sikandra Agra,
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Chemistry Class by Satyaveer Singh Sisodiya (M.Sc.(Chem.) B.Ed M.A.
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Chap-4, chemical kinetics Class-12 Dpp Questions
(Chemistry)

calcium, how much of it will remain after 10 years and 60 years if it is not lost
metabolically. (Ans. =after 10 yr= 0.78 micro gm, after 60 yr=0.227 micro gm)
Q.37 For a first order reaction, show that time required for 99% completion is twice
the time required for the completion of 90% of reaction.
Q.38 A first order reaction takes 40 min for 30% decomposition. Calculate t1/2. (Ans.
=77.7 min)
Q.39 For the decomposition of azoisopropane to hexane and nitrogen at 543 K, the
following data are obtained.
t (sec) P(mm of Hg)
0 35.0
360 54.0
720 63.0
Calculate the rate constant. (Ans. = 2.20x10-3 /sec)
Q.40 The following data were obtained during the first order thermal decomposition
of SO2Cl2 at a constant volume. SO2Cl2 (g) SO2 (g) + Cl2 (g)
–1
Exp Time/s Total pressure/atm
1 0 0.5
2 100 0.6
Calculate the rate of the reaction when total pressure is 0.65 atm.
(Ans. =7.805x10-4 atm/s)
Q.41 The rate of a reaction quadruples when the temperature changes from 293 K to
313 K. Calculate the energy of activation of the reaction assuming that it does not
change with temperature. (Ans. =52.854 kj/mol)
Q.42 The rate constant for the decomposition of hydrocarbons is 2.418 × 10–5s–1at
546 K. If the energy of activation is 179.9 kJ/mol, what will be the value of pre-
exponential factor. (Ans. = 3.912x1012)
Q.43 Consider a certain reaction A Products with k= 2.0 × 10–2s–1. Calculate
the concentration of A remaining after 100 s if the initial concentration of A is 1.0
mol L–1. (Ans. =0.135 M)
Q.45 Sucrose decomposes in acid solution into glucose and fructose accordingto the
first order rate law, with t1/2 = 3.00 hours. What fraction of sample of sucrose
remains after 8 hours ? (Ans. =0.1576)
Q.46 The decomposition of hydrocarbon follows the equation
k = (4.5 × 1011s–1) e-28000K/T Calculate Ea. (Ans. =2.32x105j/mol)
Q.47 The rate constant for the first order decomposition of H2O2 is given by the
following equation: log k = 14.34 – 1.25 × 104K/T Calculate Ea for this reaction and
at what temperature will its half-period be 256 minutes? (Ans. =739.3 K)

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Chemistry Class by Satyaveer Singh Sisodiya (M.Sc.(Chem.) B.Ed M.A.
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Chap-4, chemical kinetics Class-12 Dpp Questions
(Chemistry)

Q.48 The decomposition of A into product has value of k as 4.5 × 103 s–1 at 10°C and
energy of activation 60 kJ mol–1. At what temperature would k be 1.5 × 104s–1?
(Ans=297K)
Q.49 The time required for 10% completion of a first order reaction at 298K is equal
to that required for its 25% completion at 308K. If the value of A is 4 × 1010s–1.
Calculate k at 318K and Ea. (Ans. =Ea=76.623 kj/mol,k=1.042x10-2)

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