Chemical kinetics Questions and Answers

The rate constants k and k for two different reactions are 1016 e 2000 T and 1015 e 1000 T respectively The temperature at which k k is 2000 1 K 2 303 2 2000 K 1000 K 2 303 3 4 1000 K

2 The temperature at which a first order reaction with activation energy 191 5 kJ and Arrhenius factor of 10 2 s will have a half life period of 693 seconds is a 666 7 K b 1000 K d 333 3 K c 1555 5 K

32 Calculate the Gibb s energy change when 1 mole of NaCl is dissolved in water at 25 C Lattice energy of NaCl 777 8 KJ mol AS for dissolution 0 043 KJ mol and hydration energy of NaCl 774 1 KJ mol 1 8 114 KJ mol 2 11 4 KJ mol 3 5 4 KJ mol 1 4 4 5 KJ mol 1

67 For the reaction 2NO 2H N 2H O half life is found to be 90 sec and 10 sec when the initial pressures are 200 atm and 600 atm respectively The order of reaction is a 1 b 3 2 c 2 d 3

5 100g of a radioactive substance is disintegrated to 40g in 10 minutes The time taken to disintegrate 100g of the same substance to 6 4g is a 15 minutes c 25 minutes b 20 minutes d 30 minutes

Which of the following is are correct for a first order reaction The extent of reaction is equal to 1 e Concentration of the reactant decreases exponentially with time Concentration of the product increases exponentially with time A plot of logarithm of concentration of reactant versus time is linear with negative slone A B C D

14 Consider the plot given 1 2 NH4NO aq N g 2H O l The rate law expression for the reaction can be written as k rate constant 3 4 ON HN Time t d NH NO k dt d NH4NO K NH NO dt K NH NO 2 d NH NO K NH NO 1 4 d NH NO dt

Which of the following value of AH represent that the product is least stable 1 94 0 k cal mol 2 231 6 kcal mol 3 21 4 kcal mol 4 64 8 k cal mol For the auto ionization of water at 27 C H OH aq OH aq equilibrium constant is 10

A certain radio isotope zXA t1 2 10 days decays to given z 2YA 4 If one g atom of zXA is kept in a sealed vessel how much He will accumulate in 20 day at STP Roorkee 1987

CH3 g CH4 g H g CO g CH3 The reaction is carried out in a constant volume container at 500 C and has a half life of 14 5 min The reaction follows first order kinetics only dimethyl ether is present initially at a pressure of 0 40 atm Assuming ideal gas behaviour mark out the total pressure of the system after 12 min a 0 523 atm b 0 749 atm d 1 atm 1 66 c 0 861 atm

The rate of a first order reaction is 0 04 mol s at 10 seconds and 0 03 mol 1 s 1 at 20 second after initiation of the reaction The half life period the reaction is NEET 201 1 54 1 s 3 341 s 2 24 1 s A A 1 s

olution t K 7 t 2 303 AO log k A Example 10 A first order reaction has a specific rate constant of 2 x 10 s How much time it will take for 20 gm to reduce to 5 g 20 310 15 t 2 303 k log 2 303 2 303 20 k 5 A A log log4 10 3 0 693 25 d 1 693 1 s 2303 log le AO of 2305 107 20 4 F 2303 2x10 34

1 For a first order reaction rate constant is x 10 5 s having E 1800 kJ mol Then value a of InA at T 600K is 1 151 7 3 24 7 2 349 3 4 11 34

A radioactive sample has initial activity of 28 dpm 30 minutes After 69 3 minutes it was found to have an activity of 28 dpm Find the number of atoms in a sample having an activity of 100 dpm Divide your answer with 100

3 For a reaction 2N O 4NO O i 5 5 Initial concentration of N O is 7 2 mol L and after 20 minute NO 2 4 mol L then what will be of N O5 in K in A rate of decomposition Inmol L min Fr 2 1 1 0 06 2 0 03 3 1 3 4 2 4 5 PRO FRA

How many electrons in an atom have the following quantum numbers n 4 m 1 2 b 18 a 32 c 8 d 16

The rate constant for the formation of NOBr at 127 C is 2 x 104 times that of the NOBr at 27 C The activation energy of the reaction is approx

9 In the following first order competing reaction A Reagent Product B Reagent Prod The ratio of K K if only 50 of B will ha been reacted When 94 of A has been reacte is 1 4 06 3 2 06 2 0 246 4 0 06

mol The molar conductivity of a 0 5 m solution of AgNO3 with electrolytic conductivity of 5 76 x 10 3 S cm 1 at 298 K is X 1 0 086 S cm mol 3 2 88 S cm2 mol 2 28 8 S cm mol 4 11 52 S cm mol

3 minimum 4 maximum The strongest covalent bond is formed by the overlap of If considering for same shell 2 sand s orbitals 3 p and dorbitals 1 s and p orbitals In a triplo ho 4 p and p collateral ort

Out of following reactions which is a pseudo first order reaction Inversion of cane sugar Decomposition of ammonia on platinum surface Radioactive decay Decomposition of N O5 into NO and

At the equilibrium of the reaction N O g 2NO g the observed molar mass of N O4 is 77 70 g The percentage dissociation of N O is 1 28 4 2 46 7 3 22 4 4 18 4

D For given hypothetical elementary parallel reaction A k 2B Where k 1 k 2 k2 k 2C Initially only 2 moles of A are present The total number of moles of A B and C at the end of 75 reaction are Multiply your answer with 102

13 The half life of a substance in a certain enzyme catalysed reaction is 138 s The time required for the concentration of the substance to fall from 1 28 mg L to 0 04 mg Lis a 414 s b 552 s c 690 s d 276 s Mains 2011

A 1 These plots respectively correspond to the reaction orders a 0 2 1 1 0 2 c 1 1 2 b 0 1 2 17 If decomposition reaction A g B g follows first order kinetics then the graph of rate of formation R of B against time t will be

1 of the vessel is reduced to of its original volume 3 the rate of the reaction will 1 Increase 27 times 2 Remain unaltered 3 Increase 9 times 1 Decrease 3 times

Forward and reverse rate constant for the reaction CO g N g CO g N O g exhibit the following temperature dependence Temperature K 1200 1500 16 k M s 9 1 x 10 11 2 7 x 10 9 k M s 1 5 105 2 6 105 Is the reaction endothermic or exothermic Explain in terms of kinetics If your answer is exothermic fill your answer as 1 for endothermic fill your answer 2 in OMR

Following graph represents variation of half life period t1 2 of a nth order reaction with Ao initial concentration of the reactant 1 2

The rate of a first order reaction is 2 5 x 10 mol L min at 0 25 M concentration of reactant The half life in min of the reaction is O 69 3 O 43 5 O 76 6 38 7

A catalyst is a substance which Itself undergoes a permanent chemical change O Alters the Gibb s energy of reaction Catalysis non spontaneous reactions Increases the rate of reaction

If 40 of first order reaction was completed in 50 minutes then 50 of the same reaction would be completed in approximately Given log 3 0 47 log 5 0 7 79 minute 65 minute 61 minute

If rate constant of reaction becomes twice when temperature increases from 300 K to 310 K then activation energy in Joules of the reaction is Given log 2 0 30 O2 303 90 R O2 303 31 R O 2 303 x 90 31 2 303 x 90 x 31 R

At certain temperature the half life period in the thermal decomposition of a gaseous substance as follows P mmHg 500 t 2 in min 235 Find the order of reaction Given log 23 5 1 37 log 95 1 97 1 1 250 950 2 2 3 2 5 4 3

The suggested mechanism of a reaction is a A B D fast b A D 2C slow Write the balanced equation of the reaction if it experimentally deduced rate equation is rate k A B Find the intermediate formed during the course of the reaction Does the predicted rate law from the mechanism match the experimental rate law

122 For a reaction NO g O2 g 2NO g Rate k NO 0 if the volume of the reaction vessel is double the rate of reacti a will diminish to 1 4 of initial value b will diminish to 1 8 of initial val c will grow 4 times d will grow 8 times

for a reversible first order reaction A K Kb B k 10 2sec and Bea A eq 4 A 0 01 M and B 0 The concentration of B after 30 sec is 2 48 10 M The value of x is Given e 0 375 0 69

Which of the following is are correct statement s according to the Arrhenius equation A For given reaction the pre exponential factor has same units as that of rate constant B Higher the magnitude of activation energy greater is the temperature dependence of the rate constant C Rate constant increases with increase in temperature This is due to a greater number of collisions of molecule whose energy exceeds the activation energy Pato constant k F RT

f the activation energy of a reaction varies as E aRT bRT2 a 0 b 0 hen what will be the slope of In N versus T where N is the fraction of mol ecules having energy greater than activation energy A b B b C b a D b a

The energy profile diagram for an exothermic reaction is shown below energy reactants AE products The change in energy AE in the diagram represents the Select one O energy absorbed when bonds in the reactants break O energy difference between the reactants and the transition state O activation energy of the forward reaction

A s A g If graph between the InP and P Partial pressure of A InP 1 40000 100 the temperature at which reaction is spontaneous 1 230 K 2 300 K By the equation In P represented as

Question 2 Let build Frost diagram of P pH 0 and pH 14 at pH 12 Let find the value of pH that P change from unstable to stable state pH 0 H3PO4 0 933 H4P2O6 0 380 H3PO3 0 499 H3PO2 0 365 pH 14 PO43 1 12 HPO32 1 57 H PO2 2 05 P 0 89 P 0 100 P H 0 006 PH3 PH3

The change in concentration of a single reactant in a reaction as a function of time was followed The results of two experiments with different initial concentrations are shown in the figure on the right Estimate the value of the reaction order and the reaction rate coefficient Make sure you enter the correct unit for the reaction rate factor i know the pic is not the best but i really need your help sos tup jour A3

OCI CI OF n basic aqueous medium the following graphs are plotted dx rate of disappearance of reactant and graph not to scale dt 3 5 601 moll sec 0 7 0 3 OH 2 4 2 8 log 1 mol L Keeping OCI and OH constant 1 5 1 0 2 2 2 7 log OH mol L Keeping 1 and OCI constant 0 4 0 2 2 4 2 6 log OCI mol L Keeping 1 and OH constant Now identify the true statement s about the above reaction A Order of the reaction w r t 1 is 1 B Order of the reaction w r t OCI is 1

Compre The rate constant of reaction is related with T by Arrhenius equation Read the paragraph carefully and answer the following questio k A e fat Where k rate constant A Pre exponential factor or frequency factor e Fraction of molecules that is present in activated state E Activation energy Fraction of molecules that can cross the activation energy increases with increase in temperature or with decrease in activation energy R P Follows the above conversion graph and this first order reaction occurring at 27 C then if 102 molecules are in activated state Find the maximum rate constant A 348 10 day C 10 day B 3 46 10 day D can t be determined

The equilibrium constant of the reaction at 25 C CuSO4 5H O s CuSO4 3H O 2H O g is 1 084 10 4 atm Find out the relative humidity CuSO4 5H O will start loosing its water of crystalliziation according to above reaction Vapour pressure of water at 25 C is 24 mm of Ha

For a zero order reaction time taken for 75 completion of the reaction is x times the half life and for a first order reaction time taken 75 completion of the reaction is y times the half life Similarly for second order reaction time taken for 75 completion of the reaction z times the half life Value of 2x y z is z is

71 The number of molecules with energy greater than the threshold energy for a reac tion increases five fold by a rise of temperature from 27 C to 42 C Its energy of activation in J mol is Take In5 1 6094 R 8 314 J mol

How can one experimentally determine how many solvent accessible thiol groups there are per molecule of BSA Bovine Serum Albumin from a BSA sample of unknown concentration What would be the experimental design detailed with related calculations Ellman s reagent and related equipment spectrophotometer buffers etc are at your disposal Thanks in advance please let me know if any more information is needed and I will be sure to reply

The inversion of cane sugar proceeds with half life of 50 min at pH 5 at any concentration of sugar However if the pH 6 the half life changes to 500 min at any concentration of sugar The rate law expression for the inversion of sugar can be written as 1 r k sugar H 1 3 r k sugar H 2 4 r k sugar H r k sugar H

42 In a 1st order reaction amount of the substance left after n half lives and average life of a 1st order reaction respectively are Ao 1 A 2n k C Ao 2n 1 44 x t1 2 Q No 42 DA OB OC OD B Ao 1 n k 40 n D 1 44 x t1 2