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 seconds.
Answer :
Average rate of reaction
= 6.67 × 10^{  6}M s^{  1}
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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?
Answer :
Average rate
= 0.005 mol L^{  1} min^{  1}
= 5 ×10^{  3}M min^{  1}
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For a reaction, A + B Ã¢â€ ’Product; the rate law is given by,. What is the order of the reaction?
Answer :
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?
Answer :
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?
Answer :
Time required to decompose SO_{2}Cl_{2}to half of its initial amount is 60 minutes. If the decomposition is a first order reaction, calculate the rate constant of the reaction.
Answer :
What will be the effect of temperature on rate constant?
Answer :
The rate of the chemical reaction doubles for an increase of 10 K in absolute temperature from 298 K. Calculate E_{a}.
Answer :
The activation energy for the reaction
2HI_{(}_{g}_{)} → H_{2} + I_{2}_{(}_{g}_{)}
is 209.5 kJ mol^{1} at 581K. Calculate the fraction of molecules of reactants having energy equal to or greater than activation energy?
Answer :
From the rate expression for the following reactions, determine their order of reaction and the dimensions of the rate constants.
(i) 3 NO(g) Ã¢â€ ’ N_{2}O(g) Rate = k[NO]^{2}
(ii) H_{2}O_{2} (aq) + 3 I^{  } (aq) + 2 H^{+}Ã¢â€ ’ 2 H_{2}O (l) + Rate = k[H_{2}O_{2}][I^{  }]
(iii) CH_{3}CHO(g) Ã¢â€ ’ CH_{4}(g) + CO(g) Rate = k [CH_{3}CHO]^{3/2}
(iv) C_{2}H_{5}Cl(g) Ã¢â€ ’ C_{2}H_{4}(g) + HCl(g) Rate = k [C_{2}H_{5}Cl]
Answer :
For the reaction:
2A + B → A_{2}B
the rate = k[A][B]^{2}with k= 2.0 x 10^{6}mol^{2}L^{2}s^{1}. 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}.
Answer :
The decomposition of NH_{3}on platinum surface is zero order reaction. What are the rates of production of N_{2}and H_{2}if k = 2.5 x 10^{4}mol^{1}L s^{1}?
Answer :
The decomposition of dimethyl ether leads to the formation of CH_{4}, H_{2}and CO and the reaction rate is given by
Rate = k [CH_{3}OCH_{3}]^{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.,
If the pressure is measured in bar andtime in minutes, then what are the units of rate and rate constants?
Answer :
Mention the factors that affect the rate of a chemical reaction.
Answer :
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?
Answer :
What is the effect of temperature on the rate constant of a reaction? How can this temperature effect on rate constant be represented quantitatively?
Answer :
In a pseudo first order hydrolysis of ester in water, the following results were obtained:
t/s 
0 
30 
60 
90 
[Ester]mol L^{  1} 
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.
Answer :
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?
Answer :
In a reaction between A and B, the initial rate of reaction (r_{0}) was measured for different initial concentrations of A and B as given below:
A/ mol L^{  1} 
0.20 
0.20 
0.40 
B/ mol L^{  1} 
0.30 
0.10 
0.05 
r_{0}/ mol L^{  1} s^{  1} 
5.07 × 10^{  5} 
5.07 × 10^{  5} 
1.43 × 10^{  4} 
What is the order of the reaction with respect to A and B?
Answer :
The following results have been obtained during the kinetic studies of the reaction:
2A + B Ã¢â€ ’ C + D
Experiment 
A/ mol L^{  1} 
B/ mol L^{  1} 
Initial rate of formation of 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.
Answer :
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:
Experiment 
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} 
Answer :
Calculate the halflife of a first order reaction from their rate constants given below:
(i) 200 s^{1} (ii) 2 min^{1} (iii) 4 years^{1}
Answer :
The halflife for radioactive decay of ^{14}C is 5730 years. An archaeological artifact containing wood had only 80% of the ^{14}C found in a living tree. Estimate the age of the sample.
Answer :
The experimental data for decomposition of N_{2}O_{5}
in gas phase at 318K are given below:
t(s) 
0 
400 
800 
1200 
1600 
2000 
2400 
2800 
3200 

1.63 
1.36 
1.14 
0.93 
0.78 
0.64 
0.53 
0.43 
0.35 
(i) Plot [N_{2}O_{5}] against t.
(ii) Find the halflife period for the reaction.
(iii) Draw a graph between log [N_{2}O_{5}] and t.
(iv) What is the rate law?
(v)
Answer :
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 1/16^{th}value?
Answer :
During nuclear explosion, one of the products is ^{90}Sr with halflife of 28.1 years. If 1ÃŽÂ¼g of ^{90}Sr 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.
Answer :
For a first order reaction, show that time required for 99% completion is twice the time required for the completion of 90% of reaction.
Answer :
A first order reaction takes 40 min for 30% decomposition. Calculate t_{1/2}.
Answer :
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.
Answer :
The following data were obtained during the first order thermal decomposition of SO_{2}Cl_{2}at a constant volume.
Experiment 
Time/s^{  1} 
Total pressure/atm 
1 
0 
0.5 
2 
100 
0.6 
Calculate the rate of the reaction when total pressure is 0.65 atm.
Answer :
The rate constant for the decomposition of N_{2}O_{5} at various temperatures is given below:
T/°C 
0 
20 
40 
60 
80 

0.0787 
1.70 
25.7 
178 
2140 
Draw a graph between ln k and 1/T and calculate the values of A and E_{a}.
Predict the rate constant at 30 º and 50 ºC.
Answer :
The rate constant for the decomposition of hydrocarbons is 2.418 x 10^{5} s^{1}at 546 K. If the energy of activation is 179.9 kJ/mol, what will be the value of preexponential factor.
Answer :
Consider a certain reaction A → Products with k = 2.0 x 10^{2} s^{1}. Calculate the concentration of A remaining after 100 s if the initial concentration of A is 1.0 mol L^{1}.
Answer :
Sucrose decomposes in acid solution into glucose and fructose according to the first order rate law, with t_{1/2} = 3.00 hours. What fraction of sample of sucrose remains after 8 hours?
Answer :
The decomposition of hydrocarbon follows the equation
k = (4.5 x 10^{11} s^{1}) e^{28000} ^{K}^{/}^{T}
Calculate E_{a}.
Answer :
The rate constant for the first order decomposition of H_{2}O_{2}is given by the following equation:
log k = 14.34  1.25 x 10^{4} K/T
Calculate E_{a}for this reaction and at what temperature will its halfperiod be 256 minutes?
Answer :
The decomposition of A into product has value of k as 4.5 x 10^{3} s^{1} at 10°C and energy of activation 60 kJ mol^{1}. At what temperature would k be 1.5 x 10^{4} s^{1}?
Answer :
The time required for 10% completion of a first order reaction at 298 K is
equal to that required for its 25% completion at 308 K. If the value of A is
4 x 10^{10} s^{1}. Calculate k at 318 K and E_{a}.
Answer :
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.
Answer :
Chemistry Part1  Chemistry : CBSE NCERT Exercise Solutions for Class 12th for Chemical Kinetics will be available online in PDF book form soon. The solutions are absolutely Free. Soon you will be able to download the solutions.
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