Chemical kinetics Questions and Answers

3 For a reaction A B C the experimental rate law is found to be R K A B 2 Find the rate of the reaction when A 0 5 M B 0 1 M and k 0 03 a 4 74 x 10 2 L mol s b 5 38 x 10 2 L mol 1 2 s 1 c 5 748 x 10 2 L mol s d 4 86 x 10 2 L mol 1 2 s 1

10 The time require 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 4x1010 sec 1 1 5 1 5 2 5 calculate k at 318K Ea

The decomposition of N O in chloroform was followed by measuring the volume of O gas evolved 2N O CCI 2N O CCL O g The maximum volume of O gas obtained was 100 cm In 500 minutes 90cm of 0 was evolved The first order rate constant in min for the disappearance of N 0 i A 2 303 500 2 303 100 B log C 500 90 2 303 90 500 100 log D 100 10 500

A wooden artifact sample gave activity 32 B particles per second while the freshly cut wood gave activity of 64 B particles per second in Geiger Muller counter Calculate the age of the wooden artifact 11 2 of C 4 5760 years a 11520 years c 2880 years b 5760 years d 1440 years

Consider the data given below for a chemical reaction A B Product Experiment A B 1 2 3 O I MO I MI 2 10 5 Ms 0 2 MO I MI 2 10 5 Ms Rate of reaction 0 1 Mo 2 M 4 8 10 5 Mst The rate law for the reaction is given as OR K A B OR K B OR K A B

Concentration in M 0 8 0 8 02 Time in sec Above graph is given for the following reversible reaction X g Y g The equilibrium constant Kc of above reaction is Select an answer A 0 B C 1 2

99 For the reaction A 2B products started concentrations taken in stoichiometric proportion the experimentally determined rate law is d A k A B dt The half life time of the reaction would be 06 107

For the following electrochemical cell Pt H H C M H C M H Pt at 25 C 1 atm 1 atm given that Acid CH COOH HCOOH COOH COOH 21 pk 5 4 4 and 6 2 If He in anodic half cell arises due aq and 0 01 M HCI is taken in cathodic half cell then EMF of the above cell is 1 0 059 V 2 0 118 V 0 0005W LAY COOK COOH 73

The following data were obtained at a certain temperature for the decomposition of NH in contact with tungsten P mm initial 100 Relative in min t 2 20 5 then what will be the order of the reaction 200 10 400

6 The following data were obtained during the first order thermal decomposition of SO Cl at a constant volume SO Cl SO Cl Experiment 1 2 Calculate the rate of the reaction Time S 0 100 Total Pressure atm 0 5 0 6

23 pH of a saturated solution of Ba OH is 12 The value of solubility product Ksp of Ba OH is D AIPMT Prelims 2012 1 4 0 10 6 3 3 3 10 7 2 5 0 10 6 4 5 0 10 7 8

Use the following information to answer the question below Free Energy A B Od OC Ob d Progress of the Reaction The figure illustrates the energy states associated with the reaction A B C D Which of the following represents the delta G for non enzyme catalyzed reaction in the figure CU C D

Consider following chemical reactions Br Answer km ka Br HBr HBr Br If k 8x102 min km 2x102min n then percentage of products with a chiral carbon atom will b

The rate of decomposition of NH3 g at 10 atm of platinum surface is zero order What is rate c formation in M min of H g if rate constant of reaction 2NH3 g N2 g 3H2 g is 2 0 M min 1 h

A primary standard grade As2O3 M M 197 84 weighing 0 2068 g is dissolved in NaOH and then acidified with HCI The resulting solution is then titrated with 42 45 mL of the KMnO4 solution MnO4 8H 5e Mn 4H O H3ASO3 H O H3ASO4 2H 2e Calculate the molarity of the KMnO4 solution A B B 0 04925 C A 0 09850 D C 0 01970 D 0 03254

Q 22 54 Gas phase thermal decomposition of di tert butyl peroxide is obeying first order kinetics CH3 3C 0 0 C CH3 3 g 2 CH3 C O g C H g Total pressure at completion of the reaction is 360 torr and it is 240 torr after 10 minutes from start of the reaction then rate of disappearance of CH3 3C 0 0 C CH3 3 after 30 min is in torr min 1 04 2 87 6 93 10 2 0 14

A TA VA B T VB Diathermic and rigid partition Both compartments in the above diagram are large and contain ideal gas The initia conditions are mentioned in the diagram Select the correct statement s for the who system AS 0 if TA TB Adiabatic and rigid boundary AS 0 if T T

Rate of chemical reaction becomes 4 times when temperature is increased from 27 C to 47 C Magnitude of slope of the grap constructed between log10k y axis and x axis is Take log 02 0 30

reaction in which A B and C react to form roducts is first order in A second order in B and cero order in C Part B What is the overall order of the reaction VAE Submit Part C Bequest Answer By what factor does the reaction rate change if A is doubled and the other reactant concentrations are held const

First order gas phase thermal decomposition of N O occur as follows N 0 g 2NO g O g If total pressure varies with time as given in the figure then half life of the reaction is in minutes Take log102 0 30 10g10 5 0 70 380 Po 200 torr 0 100 min time

31 Two reactions of the same order have equal pre exponential factors but their activation energies differ by 24 9 kJ mol Calculate the ratio between the rate constant of these reactions at 27 C Gas constant R 8 3 JK mol

What is the 3rd half life of the second order decomposition of a compound given that its first half life is 20 s 1 20 s 3 80 s In the reaction 2 40 s 4 84 s 6 6

4 2 at 25 C k 2 5 min k 5 5min k3 10 8 min and k 4 7 min The Arrhenius factor is 10 min for each reaction then OAB is an endothermic process BC is an endothermic process Activation energy for the conversion BA is higher than the activation energy for the conversion BC Overall order of the reaction is 1

Q 34 54 First order gas phase thermal decomposition of N O5 occur as follows N O g 2NO g 0 8 If total pressure varies with time as given in the figure then half life of the reaction is in minutes Take log102 0 30 log10 5 0 70 380 Potal 200 torr 0 100 min time

In which of the following reaction H O acts as reducing agent I H O 2H 2e 2H O II H O 2e O 2H III H O 2e 2 OH IV H O 2OH 2e O 2H O Options are 1 I and II 2 III and IV 3 I and III 4 II and IV 79

Taking antilogs k antilog 1 9849 antilog 2 0151 1 035 x 10 s EXAMPLE 48 The rate of a particular reaction quadruples when the temperature changes from 293 to 313 K Calculate N C E R T Text book Problem the activation energy of the reaction R 8 314 JK mol

1 25 x 10 1250 K T EXAMPLE 46 The decomposition of A into product has value of k as 4 5 x 103 s at 10 C and the energy of 60 kJ mol At what temperature could k be 1 5 x 104 N C E R T Text book Soluti

Cr3 To what oxidation state was the selenium converted by the reaction A 0 276g impure sample of copper ore is dissolved and Cu2 is titrated with KI solution 1 liberated required 40 mL of 0 1 M Na S O3 solution for titration What is the of impurities in the ore A sample of 28 mL of H O aq solution required 10 mL of 0 1M KMnO4 aq solution for complete reaction in acidic medium What is the volume strength of H O For the redox reaction given below what is the value of Z XNO y As S3 2H O AsO NO SO2 H On heating 0220 g of a metallic oxide in presence of hydrogen 0 045 g of water is formed If

4 0 8 If enthalpy of neutralisation of HCI by NaOH is 57 kJ mol and with NH4OH is 50 kJ mol Calculate enthalpy of ionisation of NH4OH aq Lattice energy of NaCl s is 790 kJ mol 1 and enthalpy of hydration is 785 kJ mol Calculate enthalpy of solution of NaCl s xg sample of NH4NO3 is decomposed in a Bomb calorimeter The temperature of calorimeter increase by 4 C The heat capacity of the system is 1 25 kJ C Calculate the value of x Given molar heat of decomposition of NH4NO at constant volume is 400 kJ mol A heat engine operating between 227 C and 77 C absorbs 10 kcal of heat from the 227 C reservoir reversibly per cycle Calculate total work done in kcal in two cycles In ahamical reaction in kcal

In the Arrhenius equation for a certain reaction the value of A and E activation energy are 4 10 3 s and 98 6 kJ mol respectively If the reaction is of first order at what temperature its half life period be ten minutes Ans 311 35 K

The decomposition reaction 2N O g 2N O g O g is started in a closed cylinder under 10 s the pressure inside the assuming ideal gas isothermal isochoric condition at an initial pressure of 1 atm After Y cylinder is found to be 1 45 atm If the rate constant of the reaction is 5 10 behaviour the value of Y is

Q2 Aqueous A reacts to form R AR and in first minute in batch reactor its concentration drops from CAO 2 5 mol liter to CA 2 0 mol liter Find the rate equation for the reaction if kinetics is second order with respect to A Also find the conversion after 6 minutes 24

The decomposition of formic acid on gold surface follows first order kinetics If the rate constant at 300 K is 1 0 x 10 3 s 1 and the activation energy E 11 488 kJ mol the rate constant at 200 K is x 10 5 s Round a of to the Nearest Integer Given R 8 314 J mol K Official Ans by NTA 10

Isomerization of cyclobutene into 1 3 butadine follow first order kinetics as g g The kinetic study was performed by taking same amounts of cyclobutene in three sealed flasks First k was broken after 20 minute and the reaction mixture was absorbed completely in bromine solution 0 mL 1 0 M bromine solution was required The second flask was broken after a very long time and reaction mixture required 20 mL bromine solution of the same strength If the third flask was broken r 30 minute what volume of bromine solution of same strength would have been required

A fermentation experiment was conducted to study the production of ethanol using a new strain of Saccharomyces spp Based on the data in Table 1 determine the kinetic for ethanol production with Leudeking Piret equation 15 marks Table 1 Time h 0 123456 2 Dry biomass Glucose g L g L 0 2 0 6 2 1 2 8 4 5 9 6 2 180 150 125 98 83 24 8 Ethanol concentration g L 0 0 8 16 35 60 78 dX dt 0 0 4 1 0 1 5 1 7 1 2 0 4 dP dt 0 0 7 9 16 28 23

Determine the order of reaction its rate const The half life period of decomposition of a compound is 50 minutes If the initial concentrat the half life period is reduced to 25 minutes What is the order of reaction

The reaction CO Cl K K CI CO Cl Column I Q1 d COCI dt Q2 COCI Q3 COCI Cl COCl Cl slow Match the terms given in Column I with their correct expression given in Column II Q4 K 2CI fast K K4 A1 COCI fast K COCI follows the mechanism A2 A3 A4 A5 Column II A1 Ks COCI C1 A2 A3 1 2 K3 K CO C1 12 K K A4 A5 CI CL Ks COCI CO C K3 K K K 1 2 co C1 2

40 mmol R NH OH undergoes an electrolytic oxidation by 8 A current for 965 sec with 50 current efficiency as R NH OH H O R NO H e The process is done in 100 mL buffer solution made by 0 8 M Na HPO4 and 0 2 M Na3PO4 then find the value of x if x is pH of buffer after electrolysis For H PO4 PK 2 pka 7 pka3 pKaz 7 6 9 2 5 6 12

For the chemical reaction shown here N2 g The following data was obtained at time 0 sec N 0 60 M H 2 0 M N 0 40 M H M What is the concentration of H at 25 seconds at time 25 sec O There is There is There is There is 1 4 M H at 25 seconds 1 1 M of H 0 60 M of H at 25 seconds at 25 seconds 1 8 M of H at 25 seconds 3 H g 2 NH3 g NH3 0 0 M NH3 M

8 a a Equinormal Solutions of two weak acids HA pK 3 and HB pK 5 are each placed in contact with equal pressure of hydrogen electrode at 25 C When a cell is constructed by interconnecting them through a salt bridge find the emf of the cell 500ml water 0 5m mol of aniline K 10 9 and 50mmol of HCI

An organic compound X decomposes following two parallel first 2 order reactions with K K 1 5 and K 1 5 104 min The reaction is allowed to start with only X for 770 minutes K A B K 2 C Identify the correct statements The ratio of C to A at t 770 minutes is 5 6 The ratio of B to A at t 770 minutes is 2 3 Half life of the overall reaction is 770 minutes At t 770 minutes A B C

69 For the reaction 2A B C D the following kinetic data 69 sf4f 2A B were obtained in three separate experiments all at 298 K si fa Initial Concentration Initial 3 K A B dt Concentration A 0 1 M 0 1 M 0 2 M 0 1M The rate law for the formation of Cis 1 k A B B 0 1M 0 2M 4 2 k A B dt dc Initial rate of Formation of C moll s K A 1 2x10 1 2x10 2 4x103 dt 70 Select the incorrect order for given properties f T A 0 1 M 0 1 M 0 2 M dc 1 K AB dt dc 3 K A B dt 70 fed f

A radioactive substance A decays 20 in 12 minutes The kinetics of radioactive disintegration of the same substance A is observed using 1 gm of it Choose the correct conclusions drawn from the observations made Use log2 0 3 log 5 0 7 In2 0 69 Inx 2 3 logx Half life of the radioactive substance A 36 minutes The time required for its 60 decay 48 minutes Mass of radioactive substance A left after 180 minutes 31 25 mg Decay constant of the radioactive substance A 3 85 10 2 min

1 g atom of an a emitting XA half life 10 hr was placed in sealed containers 4 52 10 Helium atoms will accumulate in the container after A 4 52 hr C 9 40 hr B 10 00 hr D 20 00 hr

In a sample of wood the reading of the wood sample observed from the instrument is 45 dpm and in fresh sample of a tree it is 165 dpm In the absence of wood sample the instrument shows the reading of 5 dpm Identify the correct statement s 1 2 of C14 of C 4 6000 years 100 2 1 6 The age of the wood sample is 9000 years The age of the wood sample is 12000 years If the age of the wood sample is 4000 years the reading shown by instrument would by 100 dpm If the age of the wood sample is 4000 years the reading shown by instrument would be 105 dpm

A 2B C follows 1st order kinetics The reaction is started with pure A in a rigid closed vessel maintained at constant temperature After 10 sec a pin hole is developed in the vessel If the molar ratio of gases A B coming out initially is 1 2 find the rate constant of the reaction in sec1 MA 16 MB 4 Mc 8

Consider the following reaction A forward backward B The forward rate constant of the above reaction increases by 100 when its temperature is raised from 290 K to 300 K while its equilibrium constant is decreases by 50 Identify the correct statement s Energy of activation for the forward reaction is 17 4 x In2 kcal Energy of activation for the backward reaction is 8 8 x ln2 kcal The magnitude of standard heat of reaction is 17 4 In2 kcal Overall the given reaction is exothermic

2 A catalyst lower the activation energy by 5 75 kJ mol at 27 C the rate of the reaction will increase by 1 2 times of its original rate 2 5 times of its original rate 3 10 times of its original rate 4 12 times of its original rate

2 For a first order reaction following data is collected A g B g C g Time 0 20 min Total pressure 60 105 The half life of the reaction is 1 5 min 3 20 min 3 2 10 min 4 40 min Classification based on physical states solid

For adsorption of gas over solid surfac following data is obtained at 300 K 100 Pressure of gas mm of Hg Amount adsorged per kg of charcoal 3 gm 25 1 5 gm The slope of the graph between log P vs log x m will be x m and P are in same units as given 2linu 3 loups question