At Saralstudy, we are providing you with the solution of Class 12th chemistry Chemical Kinetics according to the latest NCERT (CBSE) Book guidelines prepared by expert teachers. Here we are trying to give you a detailed answer to the questions of the entire topic of this chapter so that you can get more marks in your examinations by preparing the answers based on this lesson. We are trying our best to give you detailed answers to all the questions of all the topics of Class 12th chemistry Chemical Kinetics so that you can prepare for the exam according to your own pace and your speed.
(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.
">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.
Q9 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?
">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?
Q10A/ mol L^{ - 1}
0.20 0.20 0.40B/ mol L^{ - 1}
0.30 0.10 0.05r_{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?
">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?
Q11 ExperimentA/ mol L^{ - 1}
B/ mol L^{ - 1}
Initial rate of formation of D/mol L^{ - 1} min^{ - 1}
I 0.1 0.16.0 × 10^{ - 3}
II 0.3 0.27.2 × 10^{ - 2}
III 0.3 0.42.88 × 10^{ - 1}
IV 0.4 0.12.40 × 10^{ - 2}
Determine the rate law and the rate constant for the reaction.
">The following results have been obtained during the kinetic studies of the reaction: 2A + B → 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.
Q12 ExperimentA/ mol L^{ - 1}
B/ mol L^{ - 1}
Initial rate/mol L^{ - 1} min^{ - 1}
I 0.1 0.12.0 × 10^{ - 2}
II -- 0.24.0 × 10^{ - 2}
III 0.4 0.4 -- IV -- 0.22.0 × 10^{ - 2}
">
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} |
Q13
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}
Q14The half-life 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.
Q15 t/s 0 400 800 1200 1600 2000 2400 2800 3200 10^{2} × [N_{2}O_{5}] mol L^{-1} 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 half-life period for the reaction.
(iii) Draw a graph between log[N_{2}O_{5}] 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).
">The experimental data for decomposition of N_{2}O_{5}
[2N_{2}O_{5} → 4NO_{2} + O_{2}]
in gas phase at 318K are given below:
t/s | 0 | 400 | 800 | 1200 | 1600 | 2000 | 2400 | 2800 | 3200 |
10^{2} × [N_{2}O_{5}] mol L^{-1} | 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 half-life period for the reaction.
(iii) Draw a graph between log[N_{2}O_{5}] 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).
Q16 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?">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?
Q17 During nuclear explosion, one of the products is ^{90}Sr with half-life of 28.1 years. If 1μg 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.">During nuclear explosion, one of the products is ^{90}Sr with half-life of 28.1 years. If 1μg 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.
Q18 For a first order reaction, show that time required for 99% completion is twice the time required for the completion of 90% of reaction.">For a first order reaction, show that time required for 99% completion is twice the time required for the completion of 90% of reaction.
Q19A first order reaction takes 40 min for 30% decomposition. Calculate t_{1/2}.
Q20 t (sec) P(mm of Hg) 0 35.0 360 54.0 720 63.0Calculate the rate constant
">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
Q21 The following data were obtained during the first order thermal decomposition of SO_{2}Cl_{2}at a constant volume.SO_{2}Cl_{2(}g) → SO_{2(}g) + Cl_{2}(g)
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.
">The following data were obtained during the first order thermal decomposition of SO_{2}Cl_{2}at a constant volume.
SO_{2}Cl_{2(}g) → SO_{2(}g) + Cl_{2}(g)
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.
Q22T/°C
0 20 40 60 8010^{5} X K /S^{-1}
0.0787 1.70 25.7 178 2140Draw 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.
">
The rate constant for the decomposition of N_{2}O_{5} at various temperatures is given below:
T/°C |
0 | 20 | 40 | 60 | 80 |
10^{5} X K /S^{-1} |
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.
Q23 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 pre-exponential factor.">
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 pre-exponential factor.
Q24Consider 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}.
Q25 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?">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?
Q26The decomposition of hydrocarbon follows the equation
k = (4.5 x 10^{11} s^{-1}) e^{-28000 K/T}
Calculate E_{a}.
Q27 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 half-period be 256 minutes?
">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 half-period be 256 minutes?
Q28The 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}?
Q29The 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}.
Q30 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.">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.
Give simple chemical tests to distinguish between the following pairs of compounds.
(i) Propanal and Propanone
(ii) Acetophenone and Benzophenone
(iii) Phenol and Benzoic acid
(iv) Benzoic acid and Ethyl benzoate
(v) Pentan-2-one and Pentan-3-one
(vi) Benzaldehyde and Acetophenone
(vii) Ethanal and Propanal
Henry's law constant for CO_{2} in water is 1.67 x 10^{8}Pa at 298 K. Calculate the quantity of CO_{2}in 500 mL of soda water when packed under 2.5 atm CO_{2 }pressure at 298 K.
H_{2}S, a toxic gas with rotten egg like smell, is used for the qualitative analysis. If the solubility of H_{2}S in water at STP is 0.195 m, calculate Henry's law constant.
How the following conversions can be carried out?
(i) Propene to propan-1-ol
(ii) Ethanol to but-1-yne
(iii) 1-Bromopropane to 2-bromopropane
(iv) Toluene to benzyl alcohol
(v) Benzene to 4-bromonitrobenzene
(vi) Benzyl alcohol to 2-phenylethanoic acid
(vii) Ethanol to propanenitrile
(viii) Aniline to chlorobenzene
(ix) 2-Chlorobutane to 3, 4-dimethylhexane
(x) 2-Methyl-1-propene to 2-chloro-2-methylpropane
(xi) Ethyl chloride to propanoic acid
(xii) But-1-ene to n-butyliodide
(xiii) 2-Chloropropane to 1-propanol
(xiv) Isopropyl alcohol to iodoform
(xv) Chlorobenzene to p-nitrophenol
(xvi) 2-Bromopropane to 1-bromopropane
(xvii) Chloroethane to butane
(xviii) Benzene to diphenyl
(xix) tert-Butyl bromide to isobutyl bromide
(xx) Aniline to phenylisocyanide
Calculate the mole fraction of benzene in solution containing 30% by mass in carbon tetrachloride.
A solution of glucose in water is labelled as 10% w/w, what would be the molality and mole fraction of each component in the solution? If the density of solution is 1.2 g mL^{-1}, then what shall be the molarity of the solution?
The vapour pressure of pure liquids A and B are 450 and 700 mm Hg respectively, at 350 K. Find out the composition of the liquid mixture if total vapour pressure is 600 mm Hg. Also find the composition of the vapour phase.
Calculate the mass of urea (NH_{2}CONH_{2}) required in making 2.5 kg of 0.25 molal aqueous solution.
A 5% solution (by mass) of cane sugar in water has freezing point of 271 K. Calculate the freezing point of 5% glucose in water if freezing point of pure water is 273.15 K.
A solution is obtained by mixing 300 g of 25% solution and 400 g of 40% solution by mass. Calculate the mass percentage of the resulting solution.
Predict which of the following will be coloured in aqueous solution?
Ti^{3}^{+}, V^{3}^{+}, Cu^{+}, Sc^{3}^{+}, Mn^{2}^{+}, Fe^{3+} and Co^{2}^{+}.
Give reasons for each.
If the solubility product of CuS is 6 x 10^{-16}, calculate the maximum molarity of CuS in aqueous solution.
Arrange the following compounds in increasing order of their boiling points.
CH_{3}CHO, CH_{3}CH_{2}OH, CH_{3}OCH_{3}, CH_{3}CH_{2}CH_{3}
What products would be formed when a nucleotide from DNA containing thymine is hydrolysed?
Given the standard electrode potentials,
K^{+}/ K = - 2.93V,
Ag^{+}/ Ag = 0.80V,
Hg^{2+ }/ Hg = 0.79V
Mg^{2+ }/ Mg = - 2.37 V,
Cr^{3+ }/ Cr = - 0.74V
Arrange these metals in their increasing order of reducing power.
For a first order reaction, show that time required for 99% completion is twice the time required for the completion of 90% of reaction.
A cubic solid is made of two elements P and Q. Atoms of Q are at the corners of the cube and P at the body-centre. What is the formula of the compound? What are the coordination numbers of P and Q?
Give the uses of freon 12, DDT, carbon tetrachloride and iodoform.
Draw the structures of optical isomers of:
(i) [Cr(C_{2}O_{4})_{3}]^{3-}
(ii) [PtCl_{2}(en)_{2}]^{2+}
(iii) [Cr(NH_{3})_{2}Cl_{2}(en)]^{+}
From the rate expression for the following reactions, determine their order of reaction and the dimensions of the rate constants.
(i) 3 NO(g) → N_{2}O(g) Rate = k[NO]^{2}
(ii) H_{2}O_{2} (aq) + 3 I^{ - } (aq) + 2 H^{+}→ 2 H_{2}O (l) + I_{3}^{-} Rate = k[H_{2}O_{2}][I^{ - }]
(iii) CH_{3}CHO(g) → CH_{4}(g) + CO(g) Rate = k [CH_{3}CHO]^{3/2}
(iv) C_{2}H_{5}Cl(g) → C_{2}H_{4}(g) + HCl(g) Rate = k [C_{2}H_{5}Cl]