NCERT Solutions Class 11 Chemistry Chapter 4 Chemical Kinetics Download In Pdf

Chapter 4 Chemical Kinetics Download in pdf

**Question 4.1** From the rate expression for the following reactions, determine their
order of reaction and the dimensions of the rate constants.

(i) 3NO(g) â†’ N2O (g) Rate = k[NO]2

(ii) H2O2 (aq) + 3Iâ€“ (aq) + 2H+ â†’ 2H2O (l) + 3 Iâˆ’ Rate = k[H2O2][I-]

(iii) CH3CHO (g) â†’ CH4 (g) + CO(g) Rate = k [CH3CHO]3/2

(iv) C2H5Cl (g) â†’ C2H4 (g) + HCl (g) Rate = k [C2H5Cl]

**Question 4.2** For the reaction:
2A + B â†’ A2B
the rate = k[A][B]2 with k = 2.0 Ã— 10â€“6 molâ€“2 L2 sâ€“1. Calculate the initial
rate of the reaction when [A] = 0.1 mol Lâ€“1, [B] = 0.2 mol Lâ€“1. Calculate
the rate of reaction after [A] is reduced to 0.06 mol Lâ€“1.

**Question 4.3** 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 Ã— 10â€“4 molâ€“1 L sâ€“1?

**Question 4.4** 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.,
( ) 3 3
3/2
Rate = k pCH OCH
If the pressure is measured in bar and time in minutes, then what are
the units of rate and rate constants?

**Question 4.5** Mention the factors that affect the rate of a chemical reaction.

**Question 4.6** 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 ?

**Question 4.7** What is the effect of temperature on the rate constant of a reaction? How can
this temperature effect on rate constant be represented quantitatively?

**Question 4.8** In a pseudo first order hydrolysis of ester in water, the following results were
obtained:

(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.

**Question 4.9** 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?

**Question 4.10** 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: What is the order of the reaction with respect to A and B?

**Question 4.11** The following results have been obtained during the kinetic studies of the reaction:
2A + B â†’ C + D Determine the rate law and the rate constant for the reaction.

**Question 4.12** 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:

**Question 4.13** Calculate the half-life of a first order reaction from their rate constants
given below:

(i) 200 sâ€“1

(ii) 2 minâ€“1

(iii) 4 yearsâ€“1

**
Question 4.14** 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.

**Question 4.15** The experimental data for decomposition of N2O5
[2N2O5 â†’ 4NO2 + O2]
in gas phase at 318K are given below:

(i) Plot [N2O5] against t.

(ii) Find the half-life period for the reaction.

(iii) Draw a graph between log[N2O5] and t.

(iv) What is the rate law ?

(v) Calculate the rate constant.

(vi) Calculate the half-life period from k and compare it with (ii).

**Question 4.16** The rate constant for a first order reaction is 60 sâ€“1. How much time will
it take to reduce the initial concentration of the reactant to its 1/16th
value?

**Question 4.17** During nuclear explosion, one of the products is 90Sr with half-life of
28.1 years. If 1Î¼g of 90Sr was absorbed in the bones of a newly born
baby instead of calcium, how much of it will remain after 10 years and
60 years if it is not lost metabolically.

**Question 4.18** For a first order reaction, show that time required for 99% completion
is twice the time required for the completion of 90% of reaction.

**Question 4.19** A first order reaction takes 40 min for 30% decomposition. Calculate t1/2.

**Question 4.20 **For the decomposition of azoisopropane to hexane and nitrogen at 543
K, the following data are obtained. Calculate the rate constant.

**Question 4.21** The following data were obtained during the first order thermal
decomposition of SO2Cl2 at a constant volume.
SO2Cl2 (g) â†’ SO2 (g) + Cl2 (g)

**Question 4.22 **The rate constant for the decomposition of N2O5 at various temperatures
is given below: Draw a graph between ln k and 1/T and calculate the values of A and Ea.
Predict the rate constant at 30Â° and 50Â°C.

**Question 4.23** The rate constant for the decomposition of hydrocarbons is 2.418 Ã— 10â€“5sâ€“1
at 546 K. If the energy of activation is 179.9 kJ/mol, what will be the value
of pre-exponential factor.

**Question 4.24** Consider a certain reaction A â†’ Products with k = 2.0 Ã— 10â€“2sâ€“1. Calculate
the concentration of A remaining after 100 s if the initial concentration
of A is 1.0 mol Lâ€“1.

**Question 4.25** Sucrose decomposes in acid solution into glucose and fructose according
to the first order rate law, with t1/2 = 3.00 hours. What fraction of sample
of sucrose remains after 8 hours ?

**Question 4.26** The decomposition of hydrocarbon follows the equation
k = ( 4.5 Ã— 1011sâ€“1) e-28000K/T
Calculate Ea.

**Question 4.27** The rate constant for the first order decomposition of H2O2 is given by the
following equation:
log k = 14.34 â€“ 1.25 Ã— 104K/T
Calculate Ea for this reaction and at what temperature will its half-period
be 256 minutes?

**Question 4.28** The decomposition of A into product has value of k as4.5 Ã— 103 sâ€“1 at 10Â°C
and energy of activation 60 kJ molâ€“1. At what temperature would k be
1.5 Ã— 104sâ€“1?

**Question 4.29** 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 Ã— 1010sâ€“1. Calculate k at 318K and Ea.

**Question 4.30** 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.

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- Chapter 12 Aldehydes, Ketones
- Chapter 4 Chemical Kinetics
- Chapter 5 Surface Chemistry
- Chapter 6 General Principles and Processes of Isolation of Elements
- Chapter 7 The p-Block Elements
- Chapter 8 The D- and F- Block Elements
- Chapter 9 Coordination Compounds
- Chapter 10 Haloalkanes and Haloarenes
- Chapter 11 Alcohols, Phenols and Ethers
- Chapter 14 Biomolecules
- Chapter 13 Hydrocarbons
- chapter 15 Polymers
- chapter 16 Chemistry in Everyday

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