Chemical kinetics Questions and Answers

the paragraph carefully and answer the questions given below it 4A The rate constant of a reaction following first order kinetics can be determined with th help of titrations also For example if the following decomposition is taking plac 2B aq 3C following first order kinetics if all A B and C are oxidisable wit n factors n n and no respectively During titration with an oxidizing agent Let at t 0 volume used of reagent be V Let at t t volume used of reagent be V Let at t volume used of reagent be V The rate constant for above reaction if only B and C are participating in the titrations AV 2 303 V B K A K t V C K 2 303 t 2 303 t log log V V V D K 2 303 t log 4V V log V V

Rate constant K varies with temperature as given by equation 1000 K log 0 K min T Consider the following about this equation 1 Ea is 4 606 Kcal II Pre exponential factor is 10 III Variation of log K with is linear 1 T Which of the following statements are correct I II II III I II III I III

Mark for Review Which of the following is not true regarding catalyst O Catalyst does not change equilibrium constant value O Coenzyme increases the catalytic activity of enzyme All of these hr r O Catalyst can also catalyse non spontaneous reaction

If the rate constant of a reaction is 5 8 x 10 3 s1 what is the concentration after 100 seconds if the initial concentration was 5 0 M Hint What is the order of the reaction given the units of the rate constant Your Answer

54 For a first order reaction A product the initial concentration of A is 0 1 M and after 40 minute iti becomes 0 025 M Calculate rate of reaction at reactant concentration of 0 01 M 1 3 47 10 M min 2 6 93 x 104 M min 3 3 47 x 10 5 M min 4 1 735 x 10 4 M min 16 23

C4H8 6 02 4 CO 4H O Select the correct statement 213 Rate of disappearance of O2 is 3 of production of CO2 times rate Rate of disappearance of O is times rate of production of CO2 Rate of disappearance of C4H8 and O2 is same Rate of disappearance of O is less than rate of disappearance of C4H8

Match Column l with Column II Column l contains half life expression and Column Il contains corresponding order s rate constant expression a is the initial conc of reactant x is the concentration of product at any time t and k is the rate constant Column l Q1 t 2 Q2 t 2 Q3 t 2 Q4 t1 0 586 k 0 693 k a 2k ka Column II X k t A1 K A2 K K A3 K x A4 K tLa x A5 k a 2 303 log t a a x a x a

For the reaction A K B K C K 1 78 x 10 3 min 1 and k 5 8 x 10 5 min 1 when the initial concentration of A is 0 0174 molar at O C The time at which the concentration of B is maximum is X The value of in hr is to the nearest integer X 11 log 1 78 and log 5 8 are 0 2504 and 0 7634 respectively Answer 01 02 03 04 05 06 07 08 09 01 02 03 04 05 06 07

The decomposition of sulfuryl chloride SO2C12 is a first order process The rate constant for the decomposition at 660 K is 4 5 10 2 s 1 a If we begin with an initial SO2C12 pressure of 345 torr what is the pressure of this substance after 71 s torr b At what time will the pressure of SO2C12 decline to one sixth its initial value s By what factor will the pressure of sulfuryl chloride decrease after 8 half lives Note The answer wants this value 345 torr value final pressure

d Consider a first order reversible liquid reaction in the above batch reactor A R r kICA k CR with CAO 0 5 mol liter Cro 0 After 8 minutes conversion of A is 33 3 while equilib rium conversion is 66 7 Find the rate constants ky and kr Ans kj 2

latch the reaction option A and B contain elementary reaction in Column 1 Reactions with half life and order given in Column ll 2 values and order Column 11 A1 2 A 155 Column l A B C k 5M 01 1M 2M Intial concentration 02 A 20 C D K 10 MB is solvent water 03 2 AB rate k A k 5s 04 A B rate klAl k 1 s1 A2 12 0 003 10 55 5 A3 11 2 0 693 5 A4 Order or pseudo order 1 A5 Order 2

For the reaction C4H8 6 0 4 CO 4H O Select the correct statement Rate of disappearance of O is times rate of production of CO Rate of disappearance of O is 3 times rate of production of CO2 Rate of disappearance of C4H8 and O is same Rate of disappearance of O is less than rate of disappearance of C4H8

A reactant dissociates into different products in parallel reactions as given below Reaction 1 R25 k 21 10 sec Reaction 2 2 R3T k 1 05 x 10 sec Reaction 3 nR3U ky 7 102 sec If the initial rate of disappearance of R is 0 63 atm sec when the pressure of R is 1 atm and temperature 300 K and the pre exponential factor for all three reactions is assumed to 3 sec Use In 0 21 1 56 In 0 105 2 26 In 0 07 2 66 Read Less the value of n is 4 and the initial rate of disappearance of R is same le 0 63 at R 1 atm and T 300 K then the value of ks will be Assume k and k remain unchanged 5 25 10 sec 5 25 10 4 sec1 5 25 10 sec1 6 35 x 10 10 1

2 53 The reaction SO Cl g SO g Cl g is a first order gas reaction with k 2 2 x 105 sec at 320 C The percentage 1 of SO Cl is decomposed on heatng this gas for 90 min is

latch Column 1 with Column II Column l contains half life expression and Column Il contains corresponding order s rate constant expression a is the initial conc of reactant x is the concentration of product at any time t and k is the rate constant Column l 21 1 Q2 Q3 11 Q4 72 I 0 586 0 693 19 a Column II A1 k A2 A3 k a a x A4 k 2 303 log A A5 K

A g B g Column l contains the order of a reaction which a reaction can follow and Column Il contains the graph which can relate with any of the following proper i Rate v s time ii t50 v s A o iii A v s time Column l Q1 1st order 02 2nd order 03 Zero order Q4 Pseudo first order Column Il A1 A2 A3 A4 A5

Consider the following reactions Reaction A B E 28 31 kJ Reaction 2 C D Ea 20 kJ If the initial temperature is 400 K for both reaction and the rate constants are equal then find the ratio of Arrhenius factor A A for reaction I and Z 12 18 O2 71 O 132 O 0 36

ir this yellow highlighted line is really confuse me and I c n t understand that line ease you on pen paper tell me in simple way Fraction of molecules 10 Energy of activation This area shows fraction of molecules reacting at t This area shows fraction of additional molecules which react at 10 Kinetic energy Fig 4 9 Distribution curve showing temperature dependence of rate of a reaction temperature is raised the maximum of the curve moves to the higher energy value Fig 4 9 and the curve broadens out i e spreads to the right such that there is a greater proportion of molecules with much higher energies The area under the curve must be constant since total probability must be one at all times We can mark the position of E on Maxwell Boltzmann distribution curve Fig 4 9 Increasing the temperature of the substance increases the fraction of molecules which collide with energies greater than E It is clear from the diagram that in the curve at t 10 the area showing the fraction of molecules having energy equal to or greater than activation energy gets doubled leading to doubling the rate of a reaction In the Arrhenius equation 4 18 the factor e Ea RT the fraction of molecules that have kinetic energy greater than E corresponds to Taking natural logarithm of both sides of equation 4 18 E In k In A RT 4 19 The plot of In k vs 1 T gives a straight line according to the equation 4 19 as shown in Fig 4 10

are 17 For a given exothermic reaction K and K the equilibrium constants at temperatures T and T respectively Assuming that heat of reaction is constant in temperature range between T and T AIPMT 2014 it is readily observed that 1 K K p 3 K K 2 K K p 1 K to ainstal 4 K p

The mechanism of the reaction A C is given below A B k k B fast C slow By using d B dt reaction is given by r K A 0 the rate law of the above Where k is the rate constant of the overall reaction A C If Kf 2 sec k 0 4 sec and k 0 1 sec the value of 10 k will be in units of sec

16 For the mA nB elementary reaction products A is present in excess and when the concentration of B is changed from 0 01 to 0 02 the rate of reaction becomes 4 times then the rate law determined experimentally can be Or K A m B n Or K A B 2 O r K A B r K A B

Consider the elementary parallel reaction as given below B A k G It is given that the half life period of the reactant A is 0 0693 min and at a given instant the concentration of B is 3 times the concentration of C then the value of 10k in min is

For the reaction K A B k 1 78 x 10 min 1 and k 5 8 10 5 min when the initial concentration of A is 0 0174 mola at 0 C The time at which the concentration of B is C X maximum is X The value of in hr is to the 11 nearest integer log 1 78 and log 5 8 are 0 2504 and 0 7624 rospectively

mA nB products A is present in excess and when the concentration of is changed from 0 01 to 0 02 the rate of reaction becomes 4 times then the rate law determined experimentally can be O r k A m B n Or k A B n 2 O r K A B Qr K AUB

For a reaction of the type A B C going to product the following observations are made Doubling theconcentration of A doubles the rate doubling concentration of B has no effect on the rate and tripling the concentration of C increases the rate by a Select one O A rate k A 2 B C 2 O B rate k A C 2 O C rate k A 2 B C O D rate k A B C

7 A reaction takes place in three steps with individual rate constant and activation energy Activation energy Rate constant E 180 kJ mol a1 Step 1 Step 2 Step 3 k 1 140 kJ mol k k overall rate constant k E 80 kJ mol 22 Ea 50 kJ mol 23 2 3 k k k 2 150 kJ mol overall activation energy of the reaction will be 3 130 kJ mol 4 120 kJ mol

17 For a reaction A Product the graph of half life versus initial concentration of reactant is given as tiz hr 4 2 2 2 2 The order of reaction is 1 O 2 1 A

For the reaction 2A 3B product A is present in excess When concentration of B is changed from 0 03 M to 0 06 M rate is doubled Thus rate law is 1 dx K A B 2 dx K A B dt 3 dx K A B 4 dx K A B dt

Ider the following B Ea Reaction 1 A Reaction 2 C If the initial temperature is 400 K for both reaction and the rate constants are equal then find the ratio of Arrhenius factor A A for reaction 1 and 2 O 12 18 2 71 132 ctions 28 31 kJ D E 20 kJ a

53 The reaction of NO g and O g is first order in NO g 53 and 0 9 2NO2 9 03 g N O5 g O2 g The reaction can take place by mechanism 1 NO 03 Slow NO3 0 NO3 NO N O5 II 0 fast 0 0 NO O 0 Slow NO NO fast N O Select correct mechanism 1 I only 2 II only 3 Both I and II 4 None fast NO

The gas phase reaction 2NO g H g 2N OH g was carried out and the rate law was experimentally found out to be r K NO H Consider the two mechanism 1 2NO g N O fast 2N OH g slow NOH g fast 2N OH g slow Then the mechanism consistent with the observed rate law is N O g H g II NO g H g NOH g NO g Only I Only II Both I and II Neither I nor II

For the first order gaseous reaction X 2Yg Zg the initial pressure P 90 mm of Hg The pressure after 10 minutes is 180 mm of Hg The rate constant of the reaction is 1 15 10 3 sec 1 1 15x10 sec 1 2x10 sec 1 3

27 For a first order homogeneous gaseous reaction A 2B C If the total pressure after time t was P and after long time t was P then k in terms of P P and tis 00 1 k 3 k 2 303 t 2 303 log P P P 2P log t 3 P P 2 k log 2 303 t 2 303 4 k log 2P P P P P P

Consider a first order reaction at 450 K X g Y g Z g If value of rate constant K from given data is x Then value of 10 K is Assume initially only X is present Take In a 2 3 loga and log3 0 5 and log2 0 3 Time s 0 5 Total Pressure 15 20

5 Rate constant k 1 2 x 10 Ms and E 2 0 x 102 kJ 46 k mol When T 1 A 2 0 x 10 kJ mol 2 A 1 2 x 10 M s 3 A 1 2 x 10 M S 4 A 2 4 x 10 Ms T 1 A 2 0 x 2 A 1 2 x 3 A 1 2 x 4 A 2 4 x The rate constant of the reaction A 2B is 1 0 x 10 mol 47 aff

3 Consider a first order decomposition process A A A plot of concentration of A and A v time is shown below At time t percentage of reactant decomposed is 2 Concentration A Ato no A3

pic Full Syllabus The decomposition of NH4NO into N and H O is first order reaction Which of the following graph is correct 1 2 3 log NH NO log NH NO log NH NO log NH NO time time time

sec 39 SO CL g SO g Cl g Time Exp No 1 1 7 8 x 10 3 7 8 x 10 2 0 65 atm 0 100 atm sec atm sec 4 1 x 10 2 sec P Total 0 5 0 6 ff fou 2 3 9 x 10 atm sec 4 3 9 x 10 atm sec

The rate constant for the reaction 2N O g 4NO2 g O g is 2x10 sec given temperature If the reaction is started 10 mole per lit N O then the rate of formation of N O is xx104 mole L sec at a moment at that moment concentration of O is 2g mole Lit Then x is

13 Decomposition of N O5 is first order reaction t of the reaction N O5 2NO O is 2 4 hr at 1 2 STP Starting with 10 8 gm of N O5 how much oxygen will be obtained after a period of 9 6 hr 1 1 5 litre 2 3 36 litre 3 1 05 litre 4 0 07 litre

Consider a certain reaction Reactant Product k 3 10 s S Calculate the concentration of reactant remaining after 2 303 s if the initial concentration of reactant is 1 0 mol L 1 1 0 mol L 1 0 35 mol L 1 0 5 mol L 1 8 2 mell 1

The rate constants of two reactions at two different temperatures are 1 8 10 5 mol Ls and 2 4 x 10 5 mol 1 Ls 1 The order of the reaction can be second order data insufficient zero order first order

The decomposition of H O is a first order reaction Given 20 0 min as the time for half of H O to be decomposed calculate the time it will take for the decomposition to be 86 complete 56 7 min 49 9 min 62 5 min O 61 2 min

The following data were obtained during the first order thermal Exam decomposition of N O5 g at constant volume 2 2N O5 g 2N2O4 g O g S No T 1 2 Time s 0 100 Calculate the rate constant Total Pressure atm 0 5 0 512

You experimentally determine the rate of reaction at different temperatures while keeping the init concentrations of the reactants constant What relationship would you expect to find between temperature and rate O As temperature increases rate decreases O As temperature increases rate increases The relationship depends how many reactants are present Temperature has no effect on the rate of a chemical reaction

Equal volume of 0 2 N Na2SO4 and 0 1 N BaCl2 solutions are mixed together Assume that BaSO4 is completely insoluble If K H O 0 52 K kg mol what would be the normal boiling point of the resulting solution Assume molality molarity 100 15 C 100 75 C 100 091 C 100 175 C

Consider that the multistep reaction that has the overall reaction 2A 2B C D is obtained by the following mechanism A B I 21 B C X X A D What is the overall order of the reaction 09 05 fast slow fast 012

A graph is plotted between the vapour pressure and mole fraction of a solution containing benzene and toluene Choose the correct options 80 Liquid L Pressure mmHg 60 40 20 0 0 0 2 L V b Vapour V 0 4 0 6 0 8 1 0 X benzene a At the point a the mole fraction of toluene is 0 80 b b c represents condensation c c d represents vapourization YO d c d represents vapourization as well as condensation

1 Pro Madical 2021 TT 4 19 08 2021 2 For an elementary reaction A 2B C the initial pressure of A and B are 0 5 and 1 0 atm respectively if after time t the pressure of A becomes 0 2 atm what is the ratio of rate I G 1 16 250 2 25 16 5 3 16 16 4 5

K K 3B K3 RDS A If the reaction occurred with individual rate constant K K and K3 and the activation energies associated with them are E 120 kJ mol 1 E3 51 kJ mol 1 and E 210 kJ mol respectively Determine the activation energy of the overall reaction B to C follows first order kinetics Assuming Arrhenius factor for each rate constant and overall rate constant is same 127 kJ mol 1 233 kJ mol 1 93 kJ mol 1 C 210 kJ mol 1