Chemical Reaction Quiz 5

1 / 50

Limiting reactant in a chemical reaction decides the______?

Conversion

Rate constant

Reaction speed

Equilibrium constant

2 / 50

On application of pressure to the equilibrium system, ice ? water; which of the following phenomenon will occur ?

Water will evaporate

More water will be formed

Equilibrium will not be attained

More ice will be formed

3 / 50

Pick out the wrong statement ?

Plug flow reactor (PFR) is always smaller than mixed reactor for all positive reaction orders for a particular duty

For an ideal mixed reactor at steady state, the exit stream has the same composition as fluid within the reactor and the space time is equivalent to holding time for constant density system

Reaction rate does not decrease appreciably as the reaction proceeds in case of an autocatalytic reaction

For a first order consecutive reaction, a tubular flow reactor as compared to a stirred tank reactor provides higher overall selectivity

4 / 50

Pick out the correct statement ?

The rate constant for a first order reaction does not change on changing the concentration units

A chemical reaction accompanied by absorption of heat is called an exothermic reaction

A chemical reaction accompanied by evolution of heat is called an endothermic reaction

Chemical equilibrium state is dynamic in nature

5 / 50

Overall rate of reaction in a heterogeneous catalytic reaction depends upon the mass and energy transfer from the fluid to solid surface and its rate of reaction is usually _________ the concentration of catalyst, if it does not entail a chain mechanism?

Independent of

Proportional to the square of

Proportional to

Inversely proportional to

6 / 50

In case of the irreversible unimolecular type, first order reaction, the fractional conversion at any time for constant volume system as compared to variable volume system is_____?

Either A. or B., depends on other factors

Less

Same

7 / 50

Pick out the wrong statement ?

A flat velocity profile exists in a plug flow reactor

Half life of a reaction increases with increased initial concentration for reaction orders more than one

Chemical reactions with high activation energy are very temperature sensitive

The residence time for all the elements of fluid in case of a P.F.R. need not be same

8 / 50

Oil is hydrogenated using nickel catalyst in a ___________ reactor?

Fluidised bed

Batch

Slurry

Fixed bed

9 / 50

Knudsen diffusion is directly proportional to _______?

1/?T

10 / 50

Mean residence time is equal to the space time, when__________?

The feed rate is measured at temperature and pressure in the reactor

All A., B. and C.

There is no change in number of moles in gaseous reaction

The temperature, pressure and the density of reaction mixture remains constant throughout the reactor

11 / 50

Pick out the correct statement?

In catalytic reactions, the catalyst reacts with the reactants

A catalyst cannot be recovered chemically unchanged at the end of the chemical reaction

A catalyst lowers the activation energy of the reacting molecules

A catalyst initiates a chemical reaction

12 / 50

Pick out the wrong statement pertaining to space velocity of flow reactors?

None of these

The space velocity of 3 hr-1 means that one third reactor volume of feed at specified conditions are being fed into the reactor

The unit of space velocity is (time)-1

The space velocity of 3 hr-1 means that three reactor volumes of feed at specified conditions are being fed into the reactor every hour

13 / 50

Non-catalytic fluid-solid reactions are represented by ________ model?

Unreacted core

Both A. and B.

Neither A. and B.

Continuous reaction

14 / 50

Molecularity of a reaction___________?

May not be equal to the order of reaction

Can?t have a fractional value

Both B. and C.

Is always equal to the overall order of reaction

15 / 50

Pick out the wrong statement ?

For studying a chemical reaction, it is desirable to monitor the reactants during initial stages and the products during the final stages of reaction

Study of non-ideal flow reactor is done experimentally by stimulus-response technique

A batch reactor cannot be used to study the kinetics of catalytic reaction

?Hold back? is defined as the fraction of material that stays longer than the mean residence time

16 / 50

Most important characteristics of gas-liquid reactors are the_________?

Both A. and B.

Liquid hold-up

None of these

Specific inter-facial area

17 / 50

Pick out the correct statement?

A photochemical reaction is catalysed by light

Reactions with high activation energies are very temperature sensitive

A chemical reaction occurs when the energy of the reacting molecule is less than the activation energy of the reaction

Chemical equilibrium is a static state

18 / 50

In the hydrodealkylation of toluene to benzene, the following reactions occur: C7H8 + H2 ? C6H6 + CH4 2C6H6 ? C12H10 + H2 Toluene and hydrogen are fed to a reactor in a molar ratio 1:5.80% of the toluene gets converted and the selectivity of benzene(defined as moles of benzene formed/moles of toluene converted) is 90%. The fractional conversion of hydrogen is_________?

0.136

0.16

0.152

0.144

19 / 50

In which of the following gaseous phase reversible reactions, the product yield cannot be increased by the application of high pressure ?

2SO2 + O2 ? 2SO3

N2 + O2 ? 2NO

N + 3H2 ? 2NH3

PCl3 + Cl2 ? PCl5

20 / 50

In Langmuir treatment of adsorption,__________?

Whole surface of the catalyst does not have the same activity for adsorption and there is attraction between the adsorbed molecule

Extent of adsorption is more than one complete monomolecular layer on the surface

All the adsorption does not take place by the same mechanism

Whole surface of the catalyst is essentially uniform and the adsorbed molecule has no effect on the rate of adsorption per site

21 / 50

Pick out the correct statement ?

Law of mass action was suggested by Le-Chatelier

A catalyst changes the equilibrium point

A catalyst does not change AH of the reaction

The difference between the energy of reactants and that of the products is the activation energy

22 / 50

Pick out the wrong statement ?

In a continuous flow reactor, uniform concentration cannot be maintained throughout the vessel even in a well agitated system

In a continuous flow reactor, both the reactants and the products flow out continuously

In a batch reactor, which is exclusively used for liquid phase reactions; temperature pressure and composition may vary with time

In a semi-batch reactor, one reactant is charged batch wise, while the other reactant is fed continuously

23 / 50

In which of the following gaseous phase reactions, the equilibrium of the reaction remains unaffected by pressure changes ?

2SO2 + O2 ? 2SO3

2NO2 ? N2O4

2O3 ? 3O2

N2 + O2 ? 2NO

24 / 50

Pick out the wrong statement ?

Arrhenius equation describing the effect of temperature on rate constant is given by, choiceno A K = A.e-Ea/RT

The mechanism for the decomposition of CH3CHO into CH4 and CO in presence of I2 is: CH3CHO + I2 ? CH3I + HI + CO; slow CH3I + HI ? CH4 + I2; fast Then the rate of disappearance of CH3CHO is equal to K.CCH3I.CHI and acts as a catalyst

Two mixed reactors of unequal size are available for producing a specified product, formed by a homogenous second order reaction. To achieve maximum production rate, the smaller reactor should be placed in series before the larger reactor

For the same conversion, the holding time required in a batch reactor, is always equal to the space time required in a PFR

25 / 50

Inversion of cane sugar is an example of ________?

Unimolecular reaction with second order

Unimolecular reaction with first order

Bimolecular reaction with second order

Bimolecular reaction with first order

26 / 50

In the fluid catalytic cracker (FCC), the cracking reaction is ______ (i) and the regeneration is ________ (ii) ________?

(i) exothermic (ii) exothermic

(i) endothermic (ii) endothermic

(i) endothermic (ii) exothermic

(i) exothermic (ii) endothermic

27 / 50

Ionic reactions occur in______?

Any state

Liquid state only

Solutions

Solid state only

28 / 50

In which of the following reactions, the equilibrium will shift to the right, if the total pressure is increased ?

H2 + I2 ? 2HI

N2 + O2 ? 2NO

N2O4 ? 2 NO2

H2 + Cl2 ? 2HCl

29 / 50

Organic catalysts differ from the inorganic catalyst in the sense that the former is_________?

Active at cryogenic temperatures only

Prohibitively costly

Active at very high temperature only

Proteinous in nature

30 / 50

Pick out the wrong statement ?

The order and molecularity of a complex reaction may not be the same

Visible radiation provides the necessary activation energy in photochemical reactions

For a second order reaction, the slope of the graph/plot between rate and (concentration) is equal to the rate constant (k)

Molecularity of the reaction is always a whole number greater than zero

31 / 50

Participation of ________ is involved in the occurrence of a chemical reaction?

Electrons

Protons

Neutrons

None of these

32 / 50

In the reversible reaction of the type, A + B ? AB, in general___________?

Neither of the reactions will be endothermic

The combination reaction will be endothermic, while the dissociation reaction will be exothermic

Both forward and backward reactions will be exothermic

The combination reaction will be exothermic, while the dissociation reaction will be endothermic

33 / 50

Kinetics of a solid catalysed reaction can best be studied in a __________ reactor?

None of these

Mixed

Batch

Plug-flow

34 / 50

In the gaseous phase ammonia formation reaction (N2 + 3H2 ? 2NH3), the value of the equilibrium constant depends on the__________?

Volume of the reactor

Temperature

Total pressure of the system

Initial concentration of N2 and H2

35 / 50

Photochemical reaction rate does not depend significantly on temperature, because______?

The energy of reacting molecules exceeds the activation energy by absorption of light

It is an exothermic reaction

None of these

It is a reversible reaction

36 / 50

Photo-chemical reactions occur in presence of _____?

Darkness

Sunlight

Monochromatic radiation only

Solid catalysts

37 / 50

Pick out the wrong statement ?

The fractional conversion at any time is same for both the constant as well as the variable volume system in case of an irreversible unimolecular type first order reaction

Hydrolysis of ester in presence of alkali or acid is a zero order reaction

The slowest step has the greatest influence on the overall reaction rate in case of an irreversible series reaction

Autocatalytic reactions are exemplified by microbial fermentation reactions

38 / 50

Pick out the wrong statement ?

Slow chemical reactions have generally high values of activation energy

In general, the rate of a reaction becomes triple for every 10?C rise in temperature

In a multistep reaction, the slowest step is the rate determining step

Molecularity of a reaction cannot be zero but the order of a reaction can be zero

39 / 50

Kinetics of a catalytic reaction can be best studied on a/an _______ reactor?

Differential (flow)

Either A., B. and C.

Mixed

Integral (plug flow)

40 / 50

Molecularity of an elementary reaction, P + Q ? R + S is ______?

41 / 50

In the converter of the contact process for the manufacture of H2SO4 the equilibrium conversion of SO2__________ (i) __________ with increase in temperature and __________ (ii) __________ with increase in the mole ratio of SO2 to air?

(i) decreases (ii) decreases

(i) increases (ii) increases

(i) increases (ii) decreases

(i) decreases (ii) increases

42 / 50

Pick out the wrong statement ?

A catalyst initiates a reaction

A catalyst does not alter the final position of equilibrium in a reversible reaction

A catalyst remains unchanged in chemical composition at the end the reaction

A catalyst is specific in reaction

43 / 50

Pick out the correct statement ?

The composition of equilibrium is changed by catalyst

A catalyst speeds up the forward reaction but slows shown the reverse reaction

Pressure changes do not change the equilibrium concentrations

Addition of catalyst changes the equilibrium constant

44 / 50

In solid catalysed reactions the diffusional effects are more likely to affect the overall rate of reaction for_________?

Fast reaction in catalyst of large pore diameter

Slow reactions in catalyst of small pore diameter

Slow reactions in catalyst of large pore diameter

Fast reactions in catalyst of small pore diameter

45 / 50

Pick out the wrong statement ?

Mixed reactor is always smaller than the plug flow reactor for all positive reaction orders for a particular duty

Space time in a flow reactor is a measure of its capacity and is equal to the residence time when the density of reaction mixture is constant

The vessel dispersion number (D/UL) for plug flow and mixed flow approaches zero and infinity respectively

In an ideal tubular flow reactor, mixing takes place in radial direction and there is no mixing in longitudinal direction

46 / 50

In chamber process of sulphuric acid manufacture in industry, the gas phase oxidation of SO2 to SO3 is accomplished by a _______ reaction ?

Catalytic heterogeneous

Non-catalytic homogeneous

Catalytic homogenous

Non-catalytic heterogeneous

47 / 50

Pick out the correct statement?

The dispersion number for a reactor/vessel is uL/D

A lower temperature favours the reaction of lower activation energy

Pore volume and porosity of a catalyst is measured by Brunauer-Emmett-Teller (BET) technique

The rate controlling step in a reaction involving many steps is the fastest step

48 / 50

Integral method for analysing the kinetic data is used _______?

None of these

For testing specific mechanisms with simple rate expressions

When the data are scattered

Both A. and B.

49 / 50

Maximum equilibrium conversion for endothermic reaction is obtained at the _______ temperature?

Highest possible

Intermediate

Room

Lowest possible

50 / 50

In flow reactors, the performance equations interrelate the rate of reaction to the_____?

Extent of reaction

Feed rate

Reactor volume

All A., B. and C.

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