chemical kinetics-assignment.pdf

8/14/2019 CHEMICAL KINETICS-ASSIGNMENT.pdf

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Sri Chaitanya IIT- JEE Academy

CHEMISTRY ASSIGNMENT

[Chemical Kinetics]

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1. The rate of chemical reaction (except zero order)

1)decreases from moment to moment 2) remains constant throughout

3) depends upon the order of reaction 4) none

2. Radioactive decay follows ______ order kinetics

1) 0 2) I 3) II 4) III

3. The acid hydrolysis of ester is

1) I order reaction 2) bimolecular reaction

3) Pseudo unimolecular reaction 4) none

4. The reaction CH3COOC2H5+NaOH CH3COONa+C2H5OH is

1) bimolecular reaction 2) II order reaction

3) III order reaction 4) none

5. The rate constant of a II order reaction has units

1) mole l-1sec-1 2) litre mole-1sec 3) litre mole-1sec-1 4) none of the above

6. For a reaction of II order kinetics its 1T 2 is

1) a 2) a1 3) a

2 4) a

-1

7. The reaction 2Na+Cl2= 2NaCl is found to follow III order kinetics. Its molecularity is

1) 1 2) 2 3) 3 4) 4

8. If a is the initial conc. Of a substance which reacts according to zero order kinetic and K is rate constant, the

time for the reaction to go to completion is

1) a K 2) 2 Ka 3) K a 4) 2K a

9. In a reaction, the rate is K[A] [B]2/3the O.R. is

1) 1 2) 2 3) 5 3 4) zero

10. Which one does not influence the rate of reaction

1) nature of reactant 2) conc. of reactant

3) temperature 4) molecularity

11. For the reaction A+B products, it is found that the order of A is 2 and of B is 3 in the rate expression

when conc. of both is doubled, the rate will increase by


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1) 10 2) 6 3) 32 4) 16

12. For the reaction A B, it is found that the rate of reaction increase by 8 times when the conc. of A is

doubled. The reaction is of .. O.R.

1) 1 2) 2 3) 3 4) 4

13. An increase in rate of reaction for a rise in temperature is due to

1) increase in collision frequency 2) shortening of mean free path

3) increase in the number of activated molecules 4) none

14. The rate at which a substance reacts is proportional to its

1) equivalent weights 2) molecular weights

3) number of moles 4) number of moles per litre

15. The rate constant of a reaction has same units as the rate of reaction. The rate is of

1) zero order 2) first order 3) second order 4) none of these

16. Increase in the concentration of the reactants leads to the change in

1) heat of reaction 2) activation energy

3) collision frequency 4) none of these

17. For a molecular collision to be effective, it should satisfy the following condition

1) it should involve the molecules having a certain minimum amount of energy2) it should involve only ionic compounds3) it should involve molecules having a certain minimum amount of energy and a proper orientation4) it should involve two or three molecules


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18. An endothermic reaction A B has an activation energy as x kJ mole of A. If energy change of the

reaction is y kJ, the activation energy of the reverse reactions is

1) x 2) x y 3) x+y 4) y x

19. The reactions of high molecularity are rare because

1) many body collisions have a low probability2) many body collisions are not favoured energetical3) activation energy of many body collision is very high4) activation energy of many body collision is very low

20. The activation energy of exothermic reaction A B is 20 k.cal. The heat of reaction is 50 k.cal. The

activation energy for the reaction BA will be

1) 20 k.cals 2) 30 k.cals 3) 70 k.cals 4) 50 k.cals

21. Increase in concentration of the reactants results in

1) decrease in rate of the reaction 2) increase in rate of the reaction

3) both increase or decrease in rate depending upon the nature of the reactants

4) none of the above

22. For a chemical reaction 2x+y z the rate of appearance of z is 0.05 mol L -1 per min. The rate of

disappearance of x will be

1) 0.05 mol L-1

per hour 2) 0.05 mol L-1

per min

3) 0.1 mol L-1min-1 4) 0.25 mol L-1per min

23. The activation energy of a reaction is zero. The rate constant of the reaction

1) increases with increase of temperature 2) decreases with increase of temperature

3) decreases with decrease of temperature 4) is nearly independent of temperature

24. Order of reaction is

1) always equal to its molecularity 2) always a fraction

3) always an integral number 4) the sum of the exponents in rate law

25. The specific rate of a first order reaction depends on

1) the concentration of the reactants 2) the concentration of the products

3) temperature 4) time

26. The correct expression for Arrhenius equation showing the effect of temperature on the rate constant is

1) a2 2 1

1 1 2

EK T - T

K 2.303R T T 2) a2

1 1 2

EK 1 1ln -

K R T T


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3)Ea RTK = Ae 4) a2 1 2

1 2 1

EK T Tlog =

K 2.303 T - T

27. For the first order reaction half-life is 14s. The time required for the initial concentration to reduce toth

1 8

of its value is

1) 28 s 2) 42 s 3) (14)3s 4) (14)2s

28. The rate law for the reaction

RCI+NaOH(aq) ROH+NaCl is given by, Rate = K[RCl] the rate of the reaction will be

1) doubled on doubling the concentration of sodium hydroxide2) halved on reducing the concentration of alkyl halide to one half3) decreased on increasing the temperature of the reaction4) unaffected by increasing the temperature of the reaction

29. The rate constant of a reaction depends on

1) temperature 2) mass 3) weight 4) time

30. For a given rate law 2A+B C+D, the active mass of B is kept constant but that of A is tripled. The rate

of reaction will

1) decrease by 3 times 2) increase by 9 times

3) increase by 3 times 4) unpredictable

31. Taking the reaction A+2Bproducts to be of second order which of the following is the rate law

expression for the reaction?

1)dx

= K[A][B]dt

2)2dx = K[A][B]

dt 3)

2dx = K[A] [B]dt

4)2dx = K[A]+[B]

dt

32. Consider a gaseous reaction, the rate of which is given by K[X][Y]. The volume of the reaction vessel

containing these gases is suddenly reduced to 1/4th

of the initial volume. The rate of the reaction as

compared with original rate is

1) 1/16 times 2) 16 times 3) 1/8 times 4) 8 times

33. The rate of a reaction that does not involve gases, does not depend upon

1) pressure 2) temperature 3) concentration 4) datalyst

34. For a reaction, a plot of log (a x) versus time (t) is a straight line with slope equal to K 2.303, the reaction

is of

1) zero order 2) first order 3) second order 4) third order

35. The rate constant of a reaction is 5.210-1

minutes-1

the order of the reaction is

1) one 2) zero 3) two 4) three


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36. The first order rate constant for decomposition of N2O5 is 6.9310- 4

sec-1

. What is half change time for

decomposition?

1) 102sec 2) 103sec 3) 104sec 4) 10 sec

37. The half-life period of a first order reaction is 15 minutes. The amount of substance left after one hour will be

1) one half 2) one fourth 3) one eight 4) one sixteenth

38. For a reaction A+2B C+D, the following data, were obtained

Expt. initial conc. initial conc. initial rate of

(mol. L-1) (mol L

-1) formation of D

[A] [B] (mol L-1

min-1)

1) 0.1 0.1 6.010-3

2) 0.3 0.2 7.210-2

3) 0.3 0.4 2.8810-1

4) 0.4 0.1 2.410-2

The correct rate law expression will be

1) Rate = K[A][B] 2) Rate = K[A][B]2 3) Rate = K[A]

2[B]

2 4) Rate = P[A]

2[B]

39. The rate of the reaction A+B+Cproducts is given by 1 2 1 3 1 4- d[A]

r = = K[A] [B] [C]dt

the order of

reaction is

1) 1 2) 2 3) 1 2 4) 13 12

40. In a reaction the rate was found to be independent of the concentration of the reactants. The reaction is of

1) 1storder 2) 2

ndorder 3) order 1.5 4) zero

41. Which one of the following factors does not influence the reactions rates?

1) concentrations 2) temperature 3) size of the vessel 4) catalyst

42. In a multistep reaction, the overall rate of reaction is

1) equal to the rate of slowest step 2) equal to the rate of fastest step

3) equal to the average rate of various steps 4) equal to the rate of the last step

43. Which of the following expression is correct for second order reactions (C0refers to initial concentration of

reactant)

1)1 2 0

t C 2)-1

1 2t C 3)-2

1 2 0t C 4)0

1 2 Ot C

44. The effect of temperature on reaction rate is given by

1) Clausius claperon equation 2) Arrhenius equation

3) Gibbs Helmholtz equation 4) General gas equation


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45. For a reaction pA+qBproducts, the rate law expression is r = K[A]l[B]mthen

1) (p+q) (l+m) 2) (p+q) = (l+m)

3) (p+q) may or not be equal to (l+m) 4) (p+q) > (l+m)

46. The rate of reaction 2NO+Cl2 2NOCl becomes doubled when the concentration of Cl2 is doubled

however, when the concentration of both the reactants are doubled the rate becomes eight times. What is

order of the reaction

1) first 2) second 3) third 4) zero

47. The rate constant of a reaction is 1.210-2

mol-2

lit2sec

-1. The order of reaction is

1) zero 2) 1 3) 2 4) 3

48. For the reaction A+2B+C D+2E the rate of formation of D is found to be

(a) doubled when [A] is doubled keeping [B] and [C] constant(b) doubled when [C] is doubled keeping [A] and [B] constant(c) the same when [B] is doubled keeping [A] and [C] constant.Which one is the rate equation for the reaction?

1) rate = K[A][B][C] 2) rate = K[A]0[B][C] 3) rate = K[A][B]

0[C] 4) rate = K[A][B][C]

0

49. The concentration of a reactant in a solution falls (i) from 0.2 to 0.1M in 2 hrs (ii) from 0.2 to 0.05M in 4 hr.

The order of the hydrolysis of the reactant is

1) zero 2) two 3) one 4) half

50. Two gases A and B are filled in a container, the experimental rate law for the reaction between them, has

been found to be Rate = K[A][B] predict the effect on the rate of the reaction when pressure is doubled

1) the rate is doubled 2) the rate becomes four times

3) the rate becomes eight times 4) none of the above

51. The rate of the first order reaction Xproducts is 7.510-4mol lit -1s-1. When the concentration of x is

0.5 mole L-1

. The rate constant in seconds is

1) 3.7510-4

S-1

2) 2.510-4

S1

3) 1.510-3

S1

4) 3.010-4

S-1

52. For the reaction 2A+B D,2- d[A] =K[A] [B]

dt. The expression for - d[B]

dtwill be

1) K[A]2[B] 2) 2K[A]

2[B] 3) K[2A]

2[B] 4)

21 K[A] [B]2

53. A hypothetical reaction A2+B2 2AB follows the mechanism as given below.

2A A+A (fast) 2A+B AB+B (slow) A+B AB (fast)

The order of the over all reaction is


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1) 2 2) 1 3)1

12

4) 0

54. For a chemical reaction 2X+YZ the rate of appearance of Z is 0.05 mol L-1 per min. The rate of

disappearance of x will be

1) 0.05 mol L-1per hour 2) 0.05 mol L-1per min.

3) 0.1 mol L-1min-1 4) 0.25 mol L-1per min.

55. An endothermic reaction A B has an activation energy of 10 K.cals/mole and heat of the reaction is 5

k.cals/mole. The activation energy of the reaction BA is

1) 20 k.cal/mole2) 5 k.cal/mole 3) 10 k.cal/mole4) zero

56. The decomposition of a substance R takes place according to first order kinetics. Its initial concentration is

reduced to 1/8thin 24s. The rate constant of the reaction is

1)-11 24 S 2) -10.69 16 S 3) -1ln 2 8 S 4) -11 8 S

57. The half life period of a first order reaction

2.303 a

K = logt a - x is

1) directly proportional to a 2) inversely proportional to a

3) independent of a 4) proportional to (a x)

58. The incorrect order indicated against the rate of reaction A+B C is

Rate Order Rate Order

1)d[C]

= K[A]dt

1 2)d[C]

= K[A][B]dt

2

3)0d[A] = K[A][B]

dt 2 4)

d[A]= K[A]

dt 1

59. The minimum energy necessary to permit a reaction to occur is

1) internal energy 2) threshold energy

3) activation energy 4) free energy

60. For a zero order reaction

1) 1 2 0t C 2) 1 2 0T 1 C 3)2

1 2 0t C 4)2

1 2 0t 1 C

61. A first order reaction has specific rate constant of 2 min-1. The half-life of this reaction will be

1) 1.653 min 2) 0.347 min 3) 2 min 4) 0.5 min

62. For a first order reaction we have k=100 sec-1

. The time for completion of 50% reaction is

1) 1m sec 2) 4m sec 3) 7m sec 4) 10m sec

63. For the reaction A+2B C, the rate of reaction at a given instant can be represented by


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1)d[A] 1 d[B] d[C]

+dt 2 dt dt

2)d[A] 1 d[B] d[C]

dt 2 dt dt

3)d[A] 1 d[B] d[C]

dt 2 dt dt 4)

d[A] 1 d[B] d[C]

dt 2 dt dt

64. In photochemical reactions

1) temperature has the same effect as on thermal reactions2) temperature has opposite effect as on thermal reactions3) temperature has no effect4) temperature may have a little effect in certain cases

65. In the reaction A+BAB if the concentration of A is doubled, the rate of reaction will

1) be doubled 2) be decreased to one half

3) increase four times 4) remain unaffected

66. The amount of 12853 1 2D t - 25 minutes left after 50 minutes will be

1) 1 4 2) 1 2 3) 1 3 4) none of these

67. The first order rate constant for the decomposition of N2O5 is 610-4 second-1. The half life period for the

decomposition in second is

1) 1155 2) 115.5 3) 11.55 4) 1.155

68. If the half-time for a particular reaction is found to be constant and independent of the initial concentration

of the reactions then reaction is

1) first order 2) zero order 3) second order 4) none of these

69. If initial concentration of reactants in certain reaction is doubled, the half life period of the reaction doubles,

the order of a reaction is

1) zero 2) first 3) second 4) third

70. The rate of reaction A+Bproducts is given by the equation r=K[A][B]. If B is taken in large excess, the

order of the reaction would be

1) 2 2) 1 3) 0 4) unpredictable

71. In the reaction, A+2B C+2D, the initial rate- d[A]

dtat t = 0 was found to be 2.610

-2m sec-1. What is

the value of- d[B]

dtat t = 0 in m sec

-1?

1) 2.610-2 2) 5.210

-2 3) 1.010-1 4) 6.510

-3

72. The unit of the velocity constant in case of zero order reaction is

1) conc time-1

2) conc-1

time 3) conc-1

time-1

4) conc (time)2


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73. The conversion of molecules A to B follows second order kinetics. Doubling the concentration of A will

increase the rate of formation of B by

1) a factor 2 2) a factor of 4 3) factor of 1 2 4) a factor of 1 4

74. Of the concentration of a reactant A is doubled and the rate of its reaction increases by a factor of 2, the

order of reaction with respect to A is

1) first 2) zero 3) second 4) third

75. If initial concentration is tripled, the time for half reaction is also tripled, the order of reaction is

1) zero 2) first 3) second 4) third

76. Rate of chemical reaction can be kept constant

1) by starting the components 2) by keeping the temperature

3) both of above 4) none of above

77. Which of the following into laws has an overall order of 0.5 for reaction involving substances x and y?

1) x yRate = K C C 2) 0.5

0.5x yRate = K C C

3) 11.5

x yRate = K C C

4)

1.5

x yRate = K C C

78. The hydrolysis of methyl formate in acid solution has rate expression +3rate = K HCOOCH H the

balanced equation being HCOOCH3+H2O HCOOH+CH3OH. The rate law contains+H though the

balanced equation does not contain+H because

1) more for convenience to express the rate law2) H+ion is a catalyst3) H+is an important constituent of any reaction4) All acids contain H+ions

79. In a catalytic conversion of N2to NH3by Habers process the rate of change in the concentration of NH3per

time is 4010-3mol l-1. If there is no side reaction the rate of the change as expressed in terms of hydrogen is

1)-3 -1 -160 10 mol l s 2) -1 -11200 mol l s

3)-3 -1 -12010 mol l s 4) -3 -1 -110.310 mol l s

80. In which of the following cases does the reaction go to farthest to completion?

1) k = 10 2) k = 1 3) k = 103 4) k = 10-2

81. For an exothermic reaction the energy of activation of the reactant is

1) equal to the energy of activation of products2) less than the energy of activation of products3) greater than the energy of activation of products


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4) sometimes greater and sometimes less than that of the products82. In a reaction x+yproducts, it was found that (i) on doubling the concentration of x, the rate doubled (ii)

on doubling the concentration on y, the rate of the reaction increased four times, the over all order of the

reactant is

1) 3 2) 2 3) 1 4) 0

83. The hydrolysis of ester in alkaline medium is a

1) 1storder reaction with molecularity 1 2) 2ndorder reaction with molecularity 2

3) 1storder reaction with molecularity 2 4) 2

ndorder reaction with molecularity 1

84. For the chemical change A B, it is found that the rate of reaction doubles when the concentration is

increased four times. The order A for this reaction is

1) two 2) zero 3) one 4) half

85. For reaction 4A+B 2C+2D which of the following statements is not correct?

1) the rate of disappearance of B is one fourth of the rate of disappearance of A2) the rate of appearance of C is one half the rate of disappearance of B3) the rate of formation of D is one half the rate of consumption of A4) the rates of formation of C and D are equal

86. The units for the rate constant to first order reaction is

1) S-1

2) mol L-1

S-1

3) mol S-1

4) L mol-1

S-1

87. The rate of a certain reaction at different times are as follows

Time (min) 0 10 20 30

Rate 2.810-2

2.810-2

2.8110-2

2.7910-2

(moles litre-1min-1)

the order of the reaction is

1) one 2) two 3) three 4) zero

88. The reaction, 2A+2Bproducts, the following initial rates were obtained at various initial concentrations

[A] [B] Rate (mol l-1sec-1)

0.1 M 0.2 M 0.46

0.2 M 0.2 M 1.84

0.2 M 0.1 M 0.92

The rate law for the reaction is

1) Rate = K[A]2[B]0 2) Rate = K[A][B] 3) Rate = K[A]2[B] 4) Rate = K[A][B]2


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89. The reaction 2H2O2 2H2O+O2is, 2 2r = K H O

1) zero order reaction 2) first order reaction

3) second order reaction 4) third order reaction

90. A substance A decomposes in solution following the first order kinetics. Flask I contains 1 L of 1 M solution of

A and flask II contains 100ml of 0.6 M solution. After 8 hr. the concentration of A in flask I becomes 0.25M,

what will be time for concentration of A in flask II to become 0.3M

1) 0.4 hr. 2) 2.4 hr. 3) 4.0 hr.

4) un predictable as rate constant is not given

91. The unit of rate constant for a zero order reaction is

1) litre sec-1

2) litre mole-1

sec-1

3) mole litre-1

sec-1

4) mole sec-1

92. The rate constant for a first-order reaction whose half-life is 480 sec. is

1) 1.4410-3

sec-1

2) 1.44 sec-1

3) 0.7210-3

sec-1

4) 2.8810-3

sec-1

93. The rate of a chemical reaction doubles for every 100C rise in temperature. If the rate is increased by 600C,

the rate of reaction increases by about

1) 20 times 2) 32 times 3) 64 times 4) 128 times

94. Which of the following statement about the order of reaction is true?

1) the order of a reaction increases with increase in temperature2) the order of a reaction can be determined from the balanced equation3) a second-order reaction is also bimolecular4) the order of a reaction can only be determined

95. The rate of the reaction2 2 3N (g)+3H (g) 2NH (g) was measured as

4 -1 -131 d

NH 2 10 mol L sec2 dt

. The rates of the reaction expressed in terms of N2and H2are rate in

terms of N2rate in terms of H2.

-1 -1mol L sec -1 -1mol L sec -1 -1mol L sec -1 -1mol L sec

1) 110-4 110-4 2) 310-4 110-4

3) 110-4

110-4

4) 210-4

610-4

96. The unit for specific reaction rate of second order reaction is

1) sec-1

2) mole litre-1

sec-1

3) litre2mole

-2sec

-1 4) litre mole

-1sec

-1

97. The rate of a gaseous reaction is equal to K[A][B]. The volume of the reaction vessel containing these gases

is suddenly reduced to one-fourth the initial volume. The rate of the reaction would be


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1) 1 16 2) 16 1 3) 1 8 4) 8 1

98. Diazonium salt decomposes as+ -

6 5 2 6 5 2C H N Cl C H Cl+N . At 00C, the evolution of N2becomes two

times faster when the initial concentration of the salt is doubled. Therefore it is

1) a first order reaction 2) a second order reaction

3) independent of the initial concentration of the salt 4) a zero order reaction

99. Which one of the following rate laws has an overall order of 0.5 for the reaction involving substances X, Y, Z?

1) x y zRate = K C C C 2) 0.50.5 0.5

x y zRate = K C C C

3) 11.5 0

x y zRate = K C C C

4)

0

x zRate = K C C

2

yC

100. The conversion of A B follows second order kinetics. Doubling the concentration of A will increase the

rate of reaction by a factor of

1) 2 2) 1 2 3) 4 4) 1 4

101. In the reversible reaction1

2

K

2 2 4K

2NO N O the rate of disappearance of NO2is equal to

1) 21

2

2

2K NO

K 2)

2

1 2 2 2 42K NO - 2K N O

3) 2

1 22K NO 4) 1 2 22K - K NO

102. The given reaction 2FeCl3+SnCl2 2FeCl2+SnCl4is an example of

1) first order reaction 2) second order reaction 3) third order reaction 4) none of these

103. For the reaction A+B C, it is found that doubling the concentration of A increase the rate 4 times and

doubling the concentration of B doubles the reaction rate. What is the overall order of the reaction

1) 3 2 2) 4 3) 1 4) 3

104. A first order is half completed in 45 minutes. How long does it need for 99.9% of the reaction to be

completed?

1) 20 hours 2) 10 hours 3)1

72

hours 4) 5 hours

105. In a reaction: A B, the rate of reaction increases two times on increasing the concentration of the

reactants four times, then the order of the reaction is

1) 0 2) 2 3) 1 2 4) 4

106. Milk turns sour at 400C three times as faster at as 0

0C. Hence E(activation energy) of turning of milk sour is

1)2.303 2 313 273

log 3 cal40

2)

2.303 2 313 273log (1/3) cal

40


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3)2.303 2 40

log 3 cal273 313

4)

2.303 2 40log (1/3) cal

273 313

107. A graph between log 50T , and log (conc.) for nth

order reaction is a straight line.

Reaction of this nature is completed 50% in 10 minutes when conc. is 2 mol L-1

. This

is decomposed 50% in t minutes at 4 mol L-1n and t are

1) 0.20 min 2) 1, 10 min 3) 1, 20 min 4) 0, 5 min

108. Graph between log k and1

T(k is rate constant (s

-1) and T the temperature (K)) is

a straight line with OX=5,-1 1

= Tan2.303

. Hence Eawill be

1) 2.3032 cal 2)2

cal2.303

3) 2 cal 4) none

109. Half life 1T of the first order reaction and half life 2T of the second order reaction are equal. Hence

ratio of the rate at the start of the reaction

2

1T =

rate constant initial constant

1) 1 2) 2 3) 0.693 4) 1.44

110. Rate constant k of a reaction is 0.0693 min-1

. Starting with 20 mol L-1, rate of the reaction after 10 min. will

be

1) 0.693 mol L-1min-1 2) 1.386 mol L-1min-1

3) 0.0693 mol L-1min-1 4) 6.93 mol L-1min-1

111. The rate of a chemical reaction generally increases rapidly even for small temperature increase because of a

rapid increase in the

1) collision frequency2) fraction of molecules with energies in excess of the activation energy3) activation energy4) average kinetic energy of molecules

112. For a reaction rate constant is equal to rate of the reaction of all concentrations, the order is

1) 0 2) 2 3) 3 4) 1

113. Rate constant of a reaction k is 3.010-4

s-1, energy of activation Ea= 104.4 kJ mol

-1and Arrhenius constant A

is 6.01014

s-1

at 298 K. The value of rate constant k as a Tis

1) 2.01018

s-1

2) 6.01014

s-1

3) infinite 4) 3.61030

s-1


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114. A tangent drawn on the curve obtained by plotting concentration of product (mole L-1) of a first order

reaction vs. time (min) at the point corresponding to time 20 minute makes an angle to 30 0 with

concentration axis. Hence the rate of formations of product after 20 minutes will be

1) 0.580 mole L-1

min-1

2) 1.723 mole L-1

min-1

3) 0.290 mole L-1min-1 4) 0.866 mole L-1min-1

115. For reaction 3Aproducts, it is found that the rate of reaction increases 4-fold when concentration of A

is increased 16 times keeping the temperature constant. The order of reaction is?

1) 2 2) 1 3) 3 4) 0.5

116. The reaction; 2O3 3O2, is assigned the following mechanism

I. O3 O2+O

II. O3+O 2slow

2O

The rate law of if the reaction will therefore be

1) 2

3 2r O O 2)

2 1

3 2r O O

3) 3r O 4)

2

3 2r O O

117. Decomposition of N2O5occurs in the following manner 2N2O5 4NO2+O2its rate is expressed in three

ways

(i)

2 5 11 2 5d N O

k N Odt

(ii)

2 1 2 5d NO

k N Odt

(iii)

2 11 2 5d O

k N Odt

What is the relation between k &'k

1) k ='k 2) k = 2 'k 3) 'k = 2k 4) 'k = 1 3 k

118. All chemical reactions take place at a definite rate depending on the conditions, of which the important are

1) concentration of reactants 2) temperature

3) radiation 4) presence of a catalyst

119. The rate constant of a reaction depends on

1) temperature 2) mass 3) density 4) time

120. The rate at which a substance reacts depends on its

1) atomic mass 2) equivalent mass 3) molecular mass 4) active mass

121. The rate expression for a reaction is3 2 -1rate = k[A] [B] , the order of reaction is

1) 0 2) 1 2 3) 3 2 4) 5 2

122. Which of the following rate law has an overall order of 0.5 for the reactions involving substances x, y, z?


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1) x y zRate = k C C C 2) 0.50.5 0.5

x y zRate = k C C C

3) 11.5 0

x y zRate = k C C C

4)

0

x z

2

y

R C CRate =

C

123. The reaction A(g)+2B(g) C(g)+D(g) is an elementary process. In an experiment the initial partial

pressure of A & B are PA= 0.60 and PB = 0.80 atm. When PC= 0.2 atm the rate of reaction relative to the

initial rate is

1) 1 48 2) 1 24 3) 9 16 4) 1 6

124. If concentration are measured in mole/lit and time in minutes, the unit for the rate constant of a 3rd

order

reaction are

1) mol lit-1min-12) lit2mol-2min-1 3) lit. mol-1min-1 4) min-1

125. A radioactive element has a half life period of 140 days. How much of it will remain after 1120 days

1)1

32

2)1

256

3)1

512

4)1

128

126. For a first order reaction the plot of logt

[A] Vs t is linear with a

1) positive slope and zero intercept 2) positive slope and non zero intercept

3) negative slope and zero intercept 4) negative slope and non zero intercept

127. The rate law for the reaction

RCl+NaOH(aq) ROH+NaCl

is given by Rate = k[RCl]. The rate of the reaction will be

1) unaffected by increasing temperature of the reaction2) doubled on doubling the concentration of NaOH3) halved on reducing the concentration of NaOH to one half4) halved on reducing the concentration of RCl to one half

128. For a given reaction of first order, it takes 20 minutes for the concentration to drop from 1.0 mol litre-1to 0.6

mol litre-1. The time required for the concentration to drop from 0.6 mol litre-1to 0.36 mol litre-1will be

1) more than 20 minutes 2) less than 20 minutes

3) equal to 20 minutes 4) infinity

129. The unit of rate constant of a reaction having order 1.5 would be

1) 1/ 2

-1 -1mol L s

2) 3/ 2

-1 -1mol L s

3) (conc)- 0.5

time-1

4) (conc)- 0.75

time-1

130. A catalyst lowers the activation energy of the forward reaction by 20 kJ mol-1

. It also changes the activation

energy of the backward reaction by an amount

1) equal to that of forward reaction


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2) equal to twice that of the forward reaction3) which is determined only by the average energy of products4) which is determined by the average energy of products relative to that of reactants

131. The half-life period of a radioactive element is 140 days. After 560 days, one gram of the element will reduce

to

1) 1 2 g 2) 1 4 g 3) 1 8 g 4) 1 16 g

132. For a second order reaction of the type rate = k[A]2, the plot of 1/ [A]tversus t is linear with a

1) positive slope and zero intercept 2) positive slope and non zero intercept

3) negative slope and zero intercept 4) negative slope and non zero intercept

133. The following statement(s) is (are) correct

1) A plot of log K versus 1/T is linear2) A plot of log (x) versus time is linear for a first order reaction XP3) A plot of log P versus 1/T is linear at constant volume4) A plot of P versus 1/V is linear at constant temperature

134. The decomposition of Cl2O7at 400k in the gas phase to Cl2and O2is a first order reaction

(i) After 55 seconds at 400K the pressure of Cl2O7 falls from 0.062 to 0.044 atm. The rate constant and

pressure of Cl2O7after 100 sec of decomposition at this temperature are

1) 5.210-4sec-1; 0.05 atm 2) 6.210

-3sec-1; 0.033 atm

3) 5.810

-3

sec

-1

; 0.44 atm 4) 4.610

-3

sec

-1

; 0.005 atm

135. Suppose one does not have an experimental procedure to follow the kinetics of a first order reaction with a

half life less than 0.3 nano seconds, then

1) The minimum value of rate constant that can still be measured is 2.311012sec-12) The maximum value of rate constant that can still be measured is 8.3161012hr-13) The minimum value of rate constant that can still be measured is more than 8.3161012hr-14) The maximum value of rate constant, that can still be measured is less than 510-1hr-1.

136. 75% of a 1storder reaction was completed in 32 minutes. When was 50% of the reaction completed

1) 24 min 2) 4 min 3) 16 min 4) 8 min

5) none of these

137. For a general reaction,

aA+bB cC+dD

the rate of reaction may be give as


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1)bA

A B

dC 1r = - k C C

dt a 2) a bB A B

dC 1r = - k C C

dt b

3)a bCA B

dC 1r = k C C

dt c 4) a bD

A B

dC 1r = - k C C

dt d

138. The half life of a second order reaction is

1)1/2

t = 0.693/k 2)1/2 0

t = k[A] 3)1/2 0

t = [A] / k 4)1/2

0

1t =

k[A]

139. According to Arrhenius the relationship between rate constant, k and temperature can be given by

1)- Ea RTk = Ae 2) a2 2 1

1 1 2

Ek T - Tlog =

k 2.303R T T

3) aE

logk = logA -2.303RT

4) G0= - 2.303 RT log K

140. What will be the amount of nm 1/2X t 25 min left after 50 minutes?

1) 1/2 2) 1/4 3) 1/3 4) 1/10

141. What is the activation energy for the decomposition of N2O5as 2 5 2 21

N O 2NO O2

If the values of the rate constants are 3.4510-5

and 6.910-3

at 270C and 67

0C respectively

1) 102102kJ 2) 488.5 kJ 3) 112 kJ 4) 112.5 kJ

142. 50% of the amount of a radioactive substance decomposes in 5 years. The time required for the

decomposition of 99.9% of the substance will be

1) 10 years 2) between 10 and 50 years

3) less than 10 years 4) between 49 and 50 years

143. Which one of the following statements is wrong regarding molecularity of the reaction?

1) It is calculated from the reaction mechanism2) It may be either a whole number or fraction3) It is the number of molecules of the reactants taking part in a single step chemical reaction4) It depends on the rate determining step of the reaction

144. 1.386 hours are required for the disappearance of 75% of a reactant of first-order reaction. What is the rate

constant of the reaction?

1) 3.610-3

s-1

2) 7.210-3

s-1

3) 2.710-4

s-1

4) 1.810-3

s-1

145. For a first order reaction, the ratio of time for the completion of 99.9% and half of the reaction is

1) 8 2) 10 3) 9 4) 12


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146. A certain radioactive element A, has a half-life = t seconds. In (t/2) seconds the fraction of the initial quantity

of the element so far decayed is nearly

1) 25% 2) 29% 3) 21% 4) 17%

147. The terms rate of reaction and rate of appearance (or disappearance) of reactant (or product)

1) represent one and the same physical quantity2) differ by constant factor3) are positive parameters and have same value4) may or may not have same value depending upon the stoichiometric coefficient of reactants (or

products) in the balanced chemical equation

148. For the first order reaction A(g) 2B(g)+C(g), the initial pressure is PA= 90mm Hg, the pressure after 10

minutes is found to be 180mm Hg. The rate constant of the reaction is

1) 1.1510-3

sec-1

2) 2.310-3

sec-1

3) 3.4510-3

sec-1

4) 610-3

sec-1

I. Following facts is taken to express rate of the reaction in terms of stoichiometric coefficients.

Answer the questions at the end of it.

For the reaction aA+bB cC+dD

dx 1 d[A] 1 d[B] 1 d[C] 1 d[D]= - -

dt a dt b dt c dt d dt

149. For the reaction in alkaline aqueous solution,

- -

33BrO BrO 2Br

the value of rate constant at 800C in the rate law for

-BrO

t

was found to be 0.054 L mol-1s -1. Rate

constants when the rate law is written for

- -

3BrO Br

andt t

are

k, interms of

-

3BrO

t

in terms of

-Br

t

1) 0.018 L mol-1

s-1

0.036 L mol-1

s-1

2) 0.018 L mol-1s-1 0.027 L mol-1s-1

3) 0.162 L mol-1s-1 0.108 L mol-1s-1

4) 0.162 L mol-1

s-1

0.036 L mol-1

s-1

150. Rate of formation of SO3in the following reaction

2SO2+O2 2SO3


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is 100g min-1. Hence, rate of disappearance of O2is

1) 50g min-1 2) 100g min-1 3) 200g min-1 4) 20g min-1

151. A reaction follows the given concentration time graph. The rate for this reaction at 20 seconds will be

1) 410-3M s-12) 810-3M s-13) 210-2M s-14) 110-2M s-1

152. In the following reaction:

xA yB

d[A] d[B]

log - log 0.3dt dt

where ve sign indicates rate of disappearance of the reactant. Thus, x : y is

1) 1 : 2 2) 2 : 1 3) 3 : 1 4) 3 : 10

153. For a gaseous reaction, the rate is often expressed in terms ofdP

dt

instead ofdC

dt

ordn

dt

, where C is

the concentration and n is the number of mole. Hence, relation between three expressions is

1)dC 1 dn 1 dP

dt V dt RT dt

2)

dC dn dP

dt dt dt

3)dC dn V dP

dt dt RT dt

4) none of these

154. For the reaction 2NH3 N2+3H2

3 2 21 3 2 3 3 3

d NH d N d Hk NH , k NH , k NH

dt dt dt

Then relation between1 2 3k , k and k is

1) 1.51k = 3 2k = 3k 2) 2k1= k2= 3k33) k1= k2= k3 4) k1= 3k2= 2k3

II. Consider the following statement and answer the questions at the end of it.

The rate at which a substance reacts is proportional to its active mass and the rate at which a reaction

proceeds is proportional to the product of active masses of the reacting substances.


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155. This is called .

156. For the complex reaction;

++

3 3 2Ag +2NH Ag NH

27 2 -2 -1 + 2 -1

3 3 2

dx2 10 L mol s Ag NH - 1 10 s ag NH

dt

Hence, ratio of rate constants of the forward and backward reaction is:

1) 2107L

2mol

-2 2) 210

9L

2mol

-2 3) 110

-2L

2mol

-2 4) 0.510

-9L

-2mol

2

157. In the reaction

2 2 3N +3H 2NH

3 22 -3 -3 -1

2 2 3

dx=110 M N H - 1 10 M NH

dt

3

2 2 5 2

2

3

N H dx10 M if

dtNH

is

1) 0 2) 1105 3) 110

-5 4) 110

-3

158. In the following graphical representation for the reaction A B there are two types of regions:

1) I and II both represent kinetic region at different time interval

2) I and II both represent equilibrium region at different time interval I represents kinetic while II represents

equilibrium region

3) I represents kinetic while II represents equilibrium region

4) I represents equilibrium while II represents kinetic region

159. At a given temperature, k1= k2for the reaction

A+B C+D

If1 2

dx= k [A][B] - k [C][D]

dt

In which set of the concentration reaction ceases?


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[A] [B] [C] [D]

1) 0.1 M 0.2 M 0.3 M 0.4 M

2) 0.4 M 0.25 M 0.2 M 0.5 M

3) 0.2 M 0.2 M 0.3 M 0.2 M

4) 0.2 M 0.2 M 0.4 M 0.2 M

III. For the reaction A+2B product

If rate law can be written asx ydx

= k[A] [B]dt

then x is said to be order w.r.t. A and y is said to be order w.r.t. B. If a reaction involves more than one

step, the overall reaction is obtained by adding these elementary steps. In such cases, molecularity cant

be decided by overall reaction on the basis of its stoichiometric and rate equation. However, the order of

an elementary step can be predicted from its molecularity. In fact, the order of an elementary step is

always equal to its molecularity. The slowest step is the overall rate determining step and gives order ofthe reaction.

The following reaction is first-order in A and first-order in B

A+B Product, Rate = k[A][B]

160. Relative rate of this reaction in vessels I and II of equal volume is

1) 1 : 1 2) 1 : 2 3) 2 : 1 4) 1 : 4

161. The reaction of hydrogen and iodine monochloride is represented by the equation

2 2H (g)+2ICl(g) 2HCl(g)+I (g)

This reaction is first-order in H2(g) and also first-order in ICl(g). Which of these proposed mechanism can be

consistent with the given information about this reaction?

Mechanism I :2 2H (g)+2ICl(g) 2HCl(g)+I (g)

Mechanism II : 2slowH (g)+ICl(g) HCl(g)+HI(g)

1) I only 2) II only 3) both I and II 4) neither I nor II

162. For the following reaction


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3 2 33 3CH CCl+H O CH COH+HCl

3 3dx

=k CH CCldt

, hence, rate-determining step is

1) 3 33 3CH CCl CH C Cl 2) 3 2 33 3CH CCl+H O CH COH+HCl

3) +3 2 33 3CH C +H O CH COH+H 4) H Cl HCl

IV. Following property is for the given order of a reaction. Based on this answer the questions given at the

end of it.

Time of undergoing a definite fraction of a reactant is independent of the concentration.

163. For such reactions (as above), concentration of the reactant after two average life (also called natural life

time) is reduced to

1) 0.25 2) 1 e 3) 21 e 4) 0.75

164. Which represents above-type reaction out of I, II and III?

1) I, II and III 2) I and III 3) II and III 4) I and III

165. In the following reaction A Product, I and II are two different sets of above type reaction: x is equal to

1) 10 min 2) 5 min 3) 2.5 min 4) 2 min

166. Rate constant of a reaction is 0.0693 min-1. If we start with 20 mol L-1, it is reduced to 2.5 mol L-1in

1) 10 min 2) 20 min 3) 30 min 4) 40 min

V. The rate constant for the decomposition of a certain reaction is described by the equation:

4

-1

10

1.25 10 K log k s =14 -

T

167. Pre-exponential factor for this reaction is


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1) 14 s-1

2) 1014

s-1

3) 10-14

s-1

4) 1.25104s

-1

168. Energy of activation (in kcal) is

1) 57.6 kcal 2) 1.25104kcal 3) 14.0 kcal 4) 14 kcal

169. At what temperature, rate constant is equal to pre-exponential factor?

1)

41.25 10 K T =

14

2) T = 3) T = 0 4) 414-1.25 10 K

170. What is effect on the rate of the reaction at 1270C, if in presence of catalyst, energy of activation is lower by

10 kJ mol-1

?

1) 5 times 2) 10 times 3) 7 times 4) 20 times

171. A two-step mechanism has been suggested for the reaction of nitric oxide and bromine:

1k

2 2NO(g)+Br (g) NOBr (g)

2k

2NOBr (g)+NO(g) 2NOBr(g)

Observed rate law is, rate = 2 2k[NO] Br

Hence, rate-determining step is

1)2 2NO(g)+Br (g) NOBr (g) 2) 2NOBr (g)+NO(g) 2NOBr(g)

3) 22NO(g)+Br (g) 2NOBr(g) 4) none of these

172. A reaction takes place by the following mechanism

A+BCAC+B

AC+DA+CD

The potential energy profile for this is shown below

Transition states are shown by

1) I, V 2) II, IV 3) II, III, IV 4) III only

VI. Consider the following reaction

+ 2+

2Zn+2H Zn +H

Half-life period is independent of concentration of Zn at constant pH. At constant Zn concentration, half-

life is 10 minutes at pH=2 and half-life is 100 minutes at pH=3.

173. Hence rate law is


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1)+k[Zn] H 2)

2+k[Zn] H 3)

0 +k[Zn] H 4)2

0 +k[Zn] H

VII. For the reaction A+B C

[A] [B]d[A]

-dt

1. 1.0 M 1.0 M 0.25 M min-1

2. 2.0 M 1.0 M 0.50 M min-1

3. 1.0 M 2.0 M 0.25 M min-1

174. Hence, rate law is

1) k[A] [B] 2) k[A] [B]1/2 3) k[A] 4) k[B]

VIII. Following are the values of Eaand H for three reactions carried out at the same temperature

I : Ea= 20 kJ mol-1, H = -60 kJ mol

-1

II : Ea= 10 kJ mol

-1, H = -20 kJ mol

-1

III : Ea= 40 kJ mol-1, H = +15 kJ mol

-1

175. If all the three reactions have same frequency factor then fastest and slowest reactions are

Fastest Slowest

1) I II

2) II III

3) I III

4) Cant be predicted

IX. The Arrhenius equations for the rate constant of decomposition of methyl nitrite and ethyl nitrite

-1 -1

-1 13 -1 14

1 2

152300 J mol 157700 J molk s =10 exp - and k s 10 exp -

RT RT

176. Rate constants k1and k2are equal at a temperature

1) 650 K 2) 280 K 3) 325 K 4) 65 K

X. Read the following experiments and answer the questions at the end of it.

Peroxyacetyl nitrate (PAN) is an air pollutant produced in photochemical smog by the reaction of

hydrocarbons, oxides of nitrogen, and sunlight. It dissociates as


25/37

A sample of polluted air is analysed for its PAN content which is reported as molecules PAN per litre of air

at 250C.

Time (min) Molecules 10-14

/ L air

0.0 5.010.0 4.0

20.0 3.2

30.0 2.6

40.0 2.1

50.0 1.7

60.0 1.3

177. Determine the order of the PAN decomposition reaction

1) 0 2) 1 3) 2 4) 3

178. Rate constant of the reaction is

1) 0.0231 min-1

2) 0.009 min-1

3) 0.0231 L mol-1

min-1

4) 0.009 L mol-1

min-1

179. Half-life of the reaction is

1) 10 min 2) 20 min 3) 30 min 4) 60 min

XI. Study the following experiment and answer the questions at the end of it.

The following reaction was studied at 250C in benzene solution containing 0.1M pyridine

3 6 5 6 5 33 3A B C

CH OH + C H CCl C H C.OCH HCl

The following sets of data were observed

180. Ratesd[C]

dtin sets I, II and III are respectively (in M min

-1)

I II III

1) 1.3010-4

2.610-4

1.0210-3

2) 0.033 0.0039 0.0077

3) 0.0210-4 0.0410-4 0.017


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4) none of the above

181. Rate law of the above experiment is

1) k[A] [B] 2) k[A]2[B] 3) k[A] [B]

2 4) k[A]

2[B]

0

182. Rate constant of the above experiment is 2 -2 -1in L M min

1) 1.310-1

2) 2.610-2

3) 2.610-1

4) 1.310-2

XII. Study the two photochemical reactions and answer the questions at the end.

For the overall reaction between A and B to yield C and D, two mechanisms are proposed:

I.* 5 -1 -1

1A+B AB C+D, k ' 1 10 M s

II.* 4 -1

1A A E, k 1 10 s

10 -1 -1

2E+B C+D, k 1 10 M s

(species with * are short-lived)

183. Rate law for mechanism I when concentration of each is 0.1 M, is

1) 110-7

M s-1

2) 110-6

M s-1

3) 110-5

M s-1

4) 110-4

M s-1

184. Rate law for mechanism II when concentration of each 1 M is

1) 110-4M s-1 2) 110

10M s-1 3) 110-6M s-1 4) 110

-10M s-1

185. At what concentration of B, rates of two mechanism are equal

1) 1 M 2) 5 M 3) 7 M 4) 10 M

XIII. Read the following industrial methods of H2SO4and answer the following questions at the end.

Professor Molina of the Massachusetts Institute of Technology won the 1995 Nobel Prize in Chemistry for

his work on atmospheric chemistry. One reaction that he has studied in detail is the acid rain reaction

which produces H2SO4in the atmosphere. He has proposed two possible stoichiometric reactions:

Proposal A :2 3 2 4

H O(g)+SO (g) H SO (g)

Proposal B : 2 3 2 4 22H O(g)+SO (g) H SO (g)+H O(g)

186. Using simple collision theory, what reaction orders would be expected for proposal B? Proposal B is thought

to proceed by the following two-step process

1

- 1

k

3 2 3 2kSO +2H O SO .2H O (fast)

2k

3 2 2 4 2SO .2H O H SO +H O (slow)

3 2 2 1 - 1SO .2H O is a complex which is stabilized by hydrogen bonds and k < < k or k


27/37

1) 2 3k H O SO 2) 2

2 3k H O SO 3) 3k SO 4) 2k H O

PART A

1. Sucrose decomposes in acid solution into glucose and fructose according to first order reaction, with half life

of 3.333h at 250C. What fraction of a sample of sucrose remains after 9 hrs?

[Ans: 0.15397]

2. The rate constant for the decomposition of N2O5in CCl4is 6.210-4s-1at 450C. Calculate the rate constant at

1000C if the activation energy is 103 kJ mole-1.

[Ans: 0.1935 sec-1]

3. Calculate the activation energy of a reaction which doubles in rate when the temperature is raised from 180C

to 280C

[Ans: 12.143 kcal/mole]

4. The activation energy of the reaction A+B Product, is 24.6 kcal/mole-1 at 400C. The products are

formed at the rate of 0.133M min

-1

. What will be the rate of product formation at 80

0

C?

[Ans: 11.749 M min-1]

5. The temperature coefficient of the reaction rate is 2.8. How many times will the reaction rate increase when

the temperature is raised from 20 to 750C?

[Ans: 287.7 times]

6. Two reactions proceed at 250C at the same rate, the temp. coefficient of the rate of the first reaction is 2.0

and of the second, 2.5. Find the ratio of rates of these reactions at 950C.

[Ans: 4.75 times]

7. In hydrogenation reaction at 250C, it is observed that hydrogen gas pressure falls from 2 atm to 1.2 atm

in 50 min. Calculate the rate of reaction in molarity per sec. (R = 0.082 litre atm.)

[Ans: 1.09110-5mol sec-1]

8. Decomposition of diazobenzene chloride was followed at constant temperature by measuring the volume of

nitrogen evolved at suitable intervals. Following readings were observed.

Time 0 20 55 70

Vol. of N2 0 10 25 33 162

Calculate order of the reaction.

[Ans: First]

9. For a gaseous reaction, 2A+B2 2AB, the following rate data was obtained at 3000C.

Rate of disappearance of B2 Conce. (mole/litre)

Mole litre-1

time-1

[A] [B2]

1.8

10

-3

0.015 0.15


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1.0810-2

0.09 0.15

5.410-3

0.015 0.45

Calculate the rate constant for the reaction and rate of formation of AB when A is [0.02] and [B2] is [0.04]

mole litre-1

at 3000K

[Ans: 0.8 litre mole-1min-1, 1.2810-3mole litre-1min-1]

10. Arsine decomposes on heating to give arsonic and hydrogen. The decomposition was studied at constant

volume and at constant temperature. The pressure at different times are as follows.

t (hours) 0 5.5 6.5 8

P(atm) 0.9654 1.06 1.076 1.1

Calculate the specific reaction rate assuming the reaction to be first order.

[Ans 0.039 hour-1]

11. From the following data show that the decomposition of H2O2in aqueous solution is a first order reaction.

What is the value of the rate constant?

Time in mts. 0 10 20 30 40

N 25 20 15.7 12.5 9.9

Where N is the number of ml of KMnO4required to decompose a definite volume of H2O2solution.

[Ans: 2.310-2

min-1]

12. The decomposition of N2O5according to the equation 2N2O5(g) 4NO2(g)+O2(g), is a first order reaction.

After 30 minutes from the start of the decomposition in a closed vessel, the total pressure developed is foundto be 284.5mm of Hg and on complete decomposition the total pressure is 584.5mm Hg. Calculate the rate

constant of the reaction.

[Ans: 5.205810-3

min-1]

13. At 270C it was observed, during a reaction of hydrogenation that the pressure of H2gas decreases from 2atm

to 1.1 atm in 75 min. Calculate the rate of reaction (molarity/sec). Given (R=0.082/litre atom K-1

mole-1)

[Ans: 8.1210-6

molarity sec-1]

14. Two reactions of same order have equal pre exponential factors but their activation energies differ by 24.9 kJ

mole-1. Calculate the ratio between rate constants of these reaction at 270C. (R=8.314 J K-1)

[Ans: 2.198104]

15. For a first order gaseous reaction X Y+Z, the rate constant is given by.

K=51013sec-1e

(- 54000/RT)

Where energy of activation is taken in unit of cals. Determine the temperature at which X would decompose

at the rate of 0.05% per second.

[Ans: 694.28 K]


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16. The variation of rate constant with temperature is given by the integrated form of Arrhenious equations.

a10

- Elog K = + constant

2.303 RT

If for a certain reaction

10 a

3163.0log K = - + 11.899 calculate E

T

[Ans: 14474.081 cal/mole]

17. The rate of acid catalysed ester hydrolysis of ethyl acetate in hydrochloric acid solution obeys.

Rate = -d[ester]

=K[ester] [HCl]dt

If K=0.1 M-1

h-1

at 250C, calculate the pseudo first order rate constant for HCl=0.01 molar. On this basis

calculate T1/2= Time for half change.

[Ans: 10-3hour -1: 693 hour]

18. Suppose 50 bacteria are placed in a flask containing nutrients for the bacteria so that they multiply. A study

at 350C gave following results.

Time (minutes) 0 15 30 45 60

No. of bacteria 50 100 200 400 800

Show that rate of production of bacteria is first order.

How many bacteria will be after 3 hours?

[Ans: 2.04105]

19. The activation energy of the reaction A+B Product is 24.6 kcal/mole at 400C. The products are formed

at the rate of 0.133M per minute. What will be the rate of product formation at 800C?

[Ans: R2= 88.34450.133=11.749 M min-1]

20. The decomposition of hydrogen peroxide in an aqueous solution is a first order reaction. Course of reaction is

studied by titrating the 10ml reaction mixture after various time intervals. From the following data calculate

the rate constant of the reaction.

Time (seconds) 0 600 1200

KMnO4 22.8 13.8 8.2

[Ans: K=8.44610-4sec-1]

21. For the thermal decomposition of 2-nitro propane at 3000C, the activation energy is 39.3 kcal and the value

of the constant A(frequency constant) is 1.111011sec-1. What is the half life period of the reaction at 3000C?

(R=2 cal)


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[Ans: 4883.9 sec]

22. Two reactions (I)A Products (II) B Products follow first order kinetics. The rate of the reaction

(I) is doubled when temperature is raised from 300K to 310 K. The half life for this reaction at 310 K is 30

minutes. At the same temperature B decomposes twice as fast as A. If the energy of activation for the

reaction (II) is half that of reaction (I), calculate the rate constant of reaction (II) at 300K.

[Ans: 0.0327 min-1]

23. The gas has phase decomposition of dimethyl ether follows first order of kinetics.

CH3COCH3 CH4+H2+CO. The reaction is carried at constant volume container at 5000C and has a half

life of 14.5 mins. Initially only diethyl ether is present at a pressure of 0.4 atm. What is the total pressure of

the system after 12 mins.

[Ans: 0.7488 atm]

24. Azomethane decomposes according to the equation 3 2 2 6 22CH N C H N . The reaction was

studied in a 200ml flask at 3000C. The data obtained were as follows.

T/min 0 15 30 48 75

Ptotal/min 36.2 42.4 46.5 53.1 59.3

Calculate rate constant and half life

[Ans: K=1.2610-2

m-1

55 mts]

25. The half time of first order decomposition of nitramide is 2.1 hour at 150C.

NH2NO2(aq) N2O(g)+H2O(l)

If 6.2g of NH2NO2is allowed to decompose, calculate

(i) time taken for NH2NO2to decompose 99%(ii) volume of dry N2O produced at this point measured at S.T.P.

26. A drop of solution (volume 0.05 ml) contains 3.010-6

mole H+ ions. If the rate of disappearance of the H

+

ions is 1.00107M/sec, how long would it take for the H

+ions in the drop to disappear.

[Ans: 6.010-9

sec]

27. The rate law for decomposition of gaseous

N2O5: N2O5 2NO2+1

2O2

Is observed to be

2 5 2 5

- d N OK N O

dt

A reaction mechanism which has been suggested to be constant with this


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eK

2 5 2 3N O NO +NO (fast)

1K

2 3 2 2NO NO NO +NO+O (slow)

NO+NO32K

22NO (fast)

Show that mechanism is consistent with the observed rate law

28. Dimethyl ether gaseous phase decomposition is CH3OCH3 CH4+H2+CO at 750 K having rate constant

6.7210-3min-1. Calculate the time in which initial pressure of 400mm in closed container becomes 750mm.

[Ans: 85.64 min]

29. For the reaction 2NO+H2 N2O+H2O the value of dp/dt was found to be 1.5 torr/sec for a pressure of

359 torr of NO and 0.25 torr/sec for a pressure of 152 torr. The pressure of H2being constant. On the other

hand, when the pressure of NO is kept constant. On the other hand, when the pressure of NO is kept

constant. dp/dt was 1.6 torr/sec for a hydrogen pressure of 289 torr and 0.79 torr sec-1for a pressure of

147 torr. Determine order of reaction.

[Ans: OR=3]

30. A hydrogenation reaction is carried out at 500K. If the same reaction is carried out in the presence of

catalyst at the same rate. The temperature required is 400K. Calculate the activation energy of the reaction

if the catalyst lowers the activation barier by 20 kJ/mol.

[Ans: 100 kJ]

31. A radioactive element A says to B I am half of what you were when you are one fourth of what I was.

Moreover I was 1.414 times than what you were. If the half life of A is 8 days. What is the half life of B?

[Ans: 8 days]

32. The first order reaction : Sucrose Glucose+Fructose takes place at 308 K in 0.5N HCl. At time zero the

initial total rotation of the mixture is 32.40. After 10 minutes the total rotation is 28.8

0. If the rotation of

sucrose per mol is 850, that of aglucose is 74

0and fructose is 86.04

0. Calculate the half life of the reaction

[Ans: 67.2 mints]

33. The rate constant for the forward reaction A Products is given by

4-1 1.25 10

log K sec =14.34 - T

and the rate constant for the reverse reaction is 1.210-4

sec-1

at 500C. Calculate the value of maximum rate

constant possible for the backward section.

Given : Enthalpy of the reaction = -478 kJ/mol

[Ans: 10112

sec-1]

34. The decomposition of a compound P, at temp. T according to the equation


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2P(g) 4Q(g)+R(g)+S(l) is a first order reaction. After 30 min from the start of the decomposition in a

closed vessel the total pressure developed is found to be 317mm Hg and after a long period of time the total

pressure observed to be 617mm Hg. Calculate the total pressure of the vessel after 75 min. Given : Vapour

pressure of S(l) at temp. T=32.5mm Hg

[Ans: 379.73mm Hg]

35. The time required for 10% completion of a first order reaction at 3770C is 55.2min and the fraction of

molecules at 4500C have sufficient energy to react is 1.9210

-16. Calculate its rate constant at 400

0C.

Assuming the energy of activation to be constant with in this temperature range.

[Ans: K673= 7.51210-3min-1]

36. The hydrolysis of ethyl acetate CH3COOC2H5+H2O CH3COOH+C2H5OH in aqueous solution is first order

with respect to ethyl acetate. Upon varying the pH of the solution the first order rate constant varies as

follow:

pH 3 2 1

- 4 -1

1K 10 s 1.1 11 110

What is the order of the reaction with respect to H+and the value of the rate constant?

[Ans: 1.110-1

lit/mol/sec]

37. For a first order reaction A B the dependence of rate constant k on temperature is given by

10log k = 23.02

38 10

T

, where T is in Kelvin.

A 20% solution of A by mass decomposes to the extent of 25% in 20 minutes at 298 K.

What would be the % dissociation of A in the same time at 340 K, if we start with its 30% solution

[Ans: 100% dissociated]

38. The rate of first order reaction is 0.04mol lit-1

sec-1

at 10mts and 0.03 mol lit1 sec

-1 at 20 minutes after

initiation. Find half life of the reaction.

[Ans: 24.0891 minutes]

39. The vapour pressure of two miscible liquids A and B are 300mm and 500mm of Hg respectively. In a flask 10

moles of A is mixed with 12 moles of B. However as soon as solute is added A starts polymerizing into a

completely insoluble solid. The polymerisation follows first order kinetics. After 100 minutes, 0.525 moles of

solute is dissolved which arrests the polymerisation completely. The final pressure of the solution is 400mmof Hg. Estimate the rate constant of the polymerisation reaction. Assume negligible volume change on

mixing and polymerisation and ideal behaviour of final solution.

[Ans: 1.00510-4min-1]

40. Some PH3(g) is introduced in a flask at 6000C contains an inert gas. PH3proceeds to decompose into P4(g)

and H2(g) and the reaction goes to completion. The total pressure is given below as a function of time. Find

the order of the reaction and calculate the rate constant.

Time (sec) 0 60 120

P(mm Hg) 262.4 272.9 275.51 276.4


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[Ans: Ist order]

41. For two reactions (i) P Product and (ii) Q Product the order of reaction (i) is one while that of

reaction (ii) is two. At 347 K the energy of activation of reaction (i) is 55 kJ/mol but whenever this reaction is

carried out in presence of catalyst at the same temperature, the energy of activation is 53 kJ/mol. Moreover

for the reaction (ii) when temperature is increased from 298K to 308K, the rate of reaction increases as many

times as for reaction (i) in presence of catalyst. Calculate the rate constant of reaction (ii) at 318 K. If the

pre-exponential factor constant for reaction (ii) is 3.56109mol

-1lit sec

-1.

[K=7.33 mol-1

lit sec-1

]

42. The complex 2

3 5CO NH F

reacts with water according to the equation

2+ 3+

-

3 2 3 25 5CO NH F +H O CO NH H O +F and Rate=K[Complex]

a[H

+]

b

The reaction is acid catalyzed i.e., [H+] does not change during the reaction

Thus rate = K1[Complex]

a, where K

1=K[H

+]

b

Calculate a and b from the following data (t=250C)

Complex [H+]1/2

T (hr) 3/4

T (hr)

0.1 .01 1 2

0.2 .02 0.5 1

[Ans: a=1, b=1]

PART B

1. In the Arrhenious equation for a certain reaction, the value of A and Ea(activation energy) are 41013sec-1

and 98.6 kJ mole-1respectively. If the reaction is of first order, at what temperature will its half life period be

10 minutes?

[Ans: 311.30K]

2. Consider two reaction I and II. The frequency factor of I is 100 times of II. The activation energy of I is 4.6 K

cal higher than that of II. Calculate the relation in between rate constant of I and II reactions at 2270C.

[Ans: 1.006]

3. From the following data for the decomposition of NH4NO2in aqueous solution, show that the reaction is of

the first order.

Time in mts. 10 15 25

Vol. of N2in cc 6.25 9.00 13.65 35.05

4. From the following data show that the decomposition of H2O2in aqueous solution is a first order reaction.

What is the value of the rate constant?


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Time in mts 0 10 20 30 40

N 25 20 15.7 12.5 9.9

Where N is number of ml of KMnO4required to decompose a definite vol. H2O2solution

5. Ethylene oxide was decomposed in the closed vessel and found to take place as below

With the help of following data, find the velocity constant of the reaction and show that the reaction

followed first order

Time 0 5 9 18

Pressure 116.51 122.26 128.74 141.37

6. The decomposition of Cl2O7at 400 K in the gas phase to Cl2and O2is a first order reaction

(i) After 55 seconds at 400K the pressure of Cl2O7 falls from 0.062 to 0.044 atm calculate that rate

constant.

[Ans: 6.236410-3

sec-1]

(ii) Calculate the pressure of Cl2O7after 100 sec of decomposition at this temperature.

[Ans: 0.033 atm]

7. Thermal decomposition of a compound is first order. If 50% of a sample of the compound is decomposed in

120 minutes, how long will it take for 90% of the compound to decompose?

[Ans: 398.78 min]

8. For the reaction A+B C, the following data were obtained. In the first experiment when the initial

concentration of both A and B is 0.10 M, the observed initial rate of formation of C is 1.0 10-4M per minute.

In the second experiment when the initial concentration of A and B are 0.10M and 0.30M respectively. The

initial rate is 9.010-4M per minute. In the third experiment with the initial concentration of both A and B is

0.30 N, the initial rate is 2.710-3per minute.

(i) Write rate law expression for this reaction.

2dxAns: =K[A][B]dt

(ii) Calculate the value of specific rate constant for this reaction.

[Ans: 110-1litre+2mole-1time-1

9. For the reaction A+2B 2C,

The following data were obtained

Initial concentration Initial reaction rate

(mole/litre) (mole litre-1

min-1)


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[A] [B]

(i) 1.0 1.0 0.15

(ii) 2.0 1.0 0.30

(iii) 3.0 1.0 0.45

(iv) 1.0 2.0 0.15

(v) 1.0 3.0 0.15

Write down the rate law expression for this reaction giving your explanation.

10. Rate law for the following reaction.

Ester+H+Acid+Alcohol, is0

+dx K[ester] Hdt

.

What would be the effect on the rate if

(i) Concentration of ester is doubled?

(ii) Concentration of H+ion is doubled?

[Ans: (a) rate is doubled (b) remain same]

11. For the reaction A B+C, following data were obtained

t in seconds 0 900 1800

Concn. of A 50.93 19.7 7.62

Prove reaction is first order.

12. The reaction 2A+B+C D+2E, is found to be first order in A, second order in B and zero order in C.

(i) Give the rate law for the above reaction in the form of a differential equation

2 0dxAns: =K[A][B] [C]dt

(ii) What is the effect on the rate of increasing the concentration of A, B and C two times?

[Ans: 8 times]

13. A first order reaction is 50% complete in 30 minutes at 270C and in 10 minutes at 47

0C. Calculate the

reaction rate constant at 270C and the energy of activation of the reaction in kJ/mole.

[Ans: 0.0231 min-1, 43.848 kJ/mole]

14. A first order gas reaction has K=1.510-6per second at 2000C. If the reaction is allowed to run for 10 hours,

what percentage of initial concentration would have changed in the product? What is half-life of this

reaction?

[Ans: 128.3 hours, 5.25%]


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15. Decomposition of N2O5(g) into NO2(g) and O2(g) is a first order reaction. If the initial concentration of

N2O5(g), i.e., 2 5 0N O is 0.03 mole litre1, what will be concentration after 30 minutes? Rate constant of the

reaction is 1.3510-4sec-1.

[Ans: 0.0235 mole/litre]

16. The value of rate constant for decomposition of nitrogen pentoxide2 5 2 4 2

1N O N O O

2

is 3.4610

-

5at 25

0C and 4.8710

-3at 65

0C. Show that energy of activation for the reaction is 24.8 kcal/mole.

(R=1.987 cal/deg/mole)

[Ans: 24.8 kcal/mole]

17. Starting with 1 mole of a compound A, it is found that the reaction is 3/4th

completed in one hour. Calculate

the rate constant if reaction follows first order kinetics.

[Ans: 0.0231 min-1]

18. Starting with one mole of a compound A, it is found that the reaction is 3/4 completed in 1 hour. Calculate

the rate constant if the reaction is of

(a) I order (b) II order

[Ans: For I order-K=1.386 hr-1, For II order-K=3 litre mole

-1hr

-1]

19. A drop of solution (volume 0.05ml) contains 3.010-6

mole H+ions. If the rate of disappearance of the H

+ions

is 1.00107M/sec, how long would it take for the H

+ions in the drop to disappear.

[Ans: 6.010-9

sec]

20. For the reaction A Product, it was found that the order for the change with respect to A is 2

(i) How does rate vary if conc. of A is reduced by 2/3?

(ii) How does rate vary if volume of container is reduced by 2/3?

(iii) Calculate rate when [A]=2 mole litre-1

and1/2t =1 hr.

[Ans: (i) 1/9 times (ii) 9 times (iii) 2 mole litre-1

hr-1]

21. A Ist order reaction is 50% complete in 30 minutes at 270C and in 10 minutes at 470C. Calculate the

(a) Rate constant for reaction at 270C and 470C(b) Energy of activation for the reaction

[Ans: 43.85 kJ/ml]

22. The rate constant for the first order decomposition of a certain reaction is given by the equation Ln

K(sec-1)=14.34 -

41.25 10

T

Calculate :

(a) the energy of activation (b) the rate constant at 500 K

(c) At what temperature will its half life period be 256 minutes?


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[Ans: 24.83 Kl cal/ml 513 K]

23. The gas has phase decomposition of dimethyl ether follows first order of kinetics.

Cl3COCH3 CH4+H2+CO. The reaction is carried at constant volume container at 5000C and has a half

life of 14.5 mins. Initially only diethyl ether is present at a pressure of 0.4 atm. What is the total pressure of

the system after 12 mins.

[Ans: 0.7488 atoms]

24. At 3800C, the half life period for the first order of decomposition of H2O2is 360 mts. The energy of activation

of the reaction is 200 kJ/mole. Calculate the time required for 75% decomposition at 4500C.

[Ans: 20.36 mts.]

25. For the reaction 2NOCl 2NO+Cl2the rate constant is 2.810-5mol-1dm3s-1at 300K and 710

-1mol-1

dm3s-1at 400 K. Calculate the energy of activation (b) the preexponential factor (c) rate constant at 3500K.

[Ans: 101 kJ/mol 1.0911013mol-1dm3s-11610

-3]

26. At a certain temperature, the half life periods for the catalytic decomposition of ammonia were found to be

as below.

Pressure in mm Hg 50 100 200

Half life in hrs. 3.32 1.92 1.00

Find order of reaction

27. The rate constant of a second order reaction is 5.710-5

dm3mol

-1s

-1at 25

0C and 1.6410

-4dm

3 mol

-1s

-1

at 400C. Calculate activation energy and Arrhenius frequency factor.

[Ans: 13.02 kcal/mol]

28. Substance A reacts according to a first order rate law with K=510-5sec-1. (a) If the initial concentration of A

is 1 M. What is the initial rate and rate after 1 hour.

29. In the inversion of sugar in the presence of an acid following readings are obtained

Time in mts. 0 30 90 230

Rotation in degree +46.75 +41 +30.75 +12.75 -18.75

Calculate rate constant

chemical kinetics-assignment.pdf

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