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#### Chemical Kinetics Book Back Questions

12th Standard EM

Reg.No. :
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Chemistry

Time : 00:45:00 Hrs
Total Marks : 30
5 x 1 = 5
1. For a first order reaction A ⟶ B the rate constant is x min−1. If the initial concentration of A is 0.01M , the concentration of A after one hour is given by the expression.

(a)

001. e−x

(b)

1 x 10-2(1-e-60x)

(c)

(1x10-2)e-60x

(d)

none of these

2. The addition of a catalyst during a chemical reaction alters which of the following quantities? (NEET)

(a)

Enthalpy

(b)

Activation energy

(c)

Entropy

(d)

Internal energy

3. In a reversible reaction, the enthalpy change and the activation energy in the forward direction are respectively −x kJ mol-4 and kJ mol-1 Therefore , the energy of activation in the backward direction is

(a)

(y-x)kJ mol-1

(b)

(x+y)J mol-1

(c)

(x-y)KJ mol-1

(d)

(x+y)X103Jmol-1

4. Assertion: rate of reaction doubles when the concentration of the reactant is doubles if it is a first order reaction.
Reason: rate constant also doubles

(a)

Both assertion and reason are true and reason is the correct explanation of assertion.

(b)

Both assertion and reason are true but reason is not the correct explanation of assertion.

(c)

Assertion is true but reason is false

(d)

Both assertion and reason are false.

5. If the initial concentration of the reactant is doubled, the time for half reaction is also doubled. Then the order of the reaction is

(a)

Zero

(b)

one

(c)

Fraction

(d)

none

6. 3 x 2 = 6
7. What is an elementary reaction? Give the differences between order and molecularity of a reaction

8. Explain the effect of catalyst on reaction rate with an example

9. What is the order with respect to each of the reactant and overall order of the following reactions?
a) 5Br-(aq)+BrO3-(aq)+6H+(aq) ➝3Br2(l)+3H2O(l)
The experimental rate law is
Rate = k [Br−][BrO3][H+]2
b) CH3CHO(g)$\overset { \Delta }{ \longrightarrow }$ CH4(g)+CO(g) the experimental rate law is
Rate =K[CH3CHO]$\frac{3}{2}$

10. 3 x 3 = 9
11. Explain pseudo first order reaction with an example

12. Identify the order for the following reactions
(i) Rusting of Iron
(iii) $2A+3B\longrightarrow products$;rate k[A]1/2[B]2

13. (ii) 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).

14. 2 x 5 = 10
15. The activation energy of a reaction is 225 k Cal mol-1 and the value of rate constant at 40°C is 11.8X10-6s-1Calculate the frequency factor, A.

16. For the reaction R - P, the concentration of a reactant changes from 0.03 M to 0.02 M in 25 minutes. Calculate the average rate of reaction using units of time both in minutes and second.