Chemical Reaction Engineering

Question 1

The conversion for a first order liquid phase reaction.A-> Bin a CSTR is 50%. If another CSTR of the same volume is connected in series, then the % conversion at the exit of the second reactor will be

Answer 1

75%

Question 2

What is the dispersion number for a CSTR?

Answer 2

∞

Question 3

Bulk diffusion in catalyst pore __________ with increase in pressure.

Answer 3

decreases

Question 4

The concentration of A in a first order reaction,A->B, decreases

Answer 4

exponentially with time.

Question 5

A chemical reaction occurs, when the energy of the reacting molecules is __________ the activation energy of reaction.

Answer 5

equal to or more than

Question 6

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

Answer 6

0.144

Question 7

The residence time distribution of an ideal CSTR is

Answer 7

exp(-t/τ)

Question 8

The enzyme which can catalyse the conversion of glucose to ethyl alcohol is

Answer 8

zymase

Question 9

The conversion of a reactant, undergoing a first order reaction, at a time equal to three times the half life of the reaction is

Answer 9

0.875

Question 10

In case of unimolecular type elementary reaction,, plug flow reactor as compared to mixed reactor is

Answer 10

more

Question 11

What is the value of ‘n’ if the reaction rate of the chemical reaction A->B, is proportional to CA^n and it is found that the reaction rate triples, when the concentration of ‘A’ is increased 9 times ?

Answer 11

1/2

Question 12

A second order reaction of the formA+B -> Cis called a pseudo-first order reaction, when

Answer 12

CB0≥CB0

Question 13

Inversion of cane sugar is an example of

Answer 13

bimolecular reaction with first order.

Question 14

Pressure changes do not change the equilibrium concentrations.

Answer 14

correctuee

Question 15

The rate of a gas phase reaction is given byK.CA.CB. If the volume of the reaction vessel is reduced to l/4th of its initial volume, then the reaction rate compared to the original rate will be __________ times.

Answer 15

16

Question 16

Overall rate of reaction in a heterogenous 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.

Answer 16

proportional to

Question 17

__________ resistance is not involved in the combustion of a carbon particle.

Answer 17

Ash

Question 18

B.E.T. method of finding out surface area of a catalyst, uses the extension of __________ isotherm.

Answer 18

Langmuir

Question 19

For a packed bed reactor; the presence of a long tail in the residence time distribution curve is an indication of

Answer 19

dead zone

Question 20

Cold shot cooling is only practical when the feed temperature is __________ than the reaction temperature.

Answer 20

much lower

Question 21

A first order reactionA->Boccurs in an isothermal porous catalyst pellet of spherical shape. If the concentration ofAat the centre of the pellet is much less than at the external surface, the process is limited by

Answer 21

diffusion within the pellet.

Question 22

The following half life data are available for the irreversible liquid phase reactionA -> products.
Cao half life
2 2
8 1
The overall order of reaction is

Answer 22

1.5

Question 23

With increase in the order of reaction (for all positive reaction orders), the ratio of the volume of mixed reactor to the volume of plug flow reactor (for identical feed composition, flow rate and conversion)

Answer 23

increases

Question 24

Reaction of benzene with chlorine gas to produce tri-chlorobenzene exemplifies a/an __________ reaction.

Answer 24

consecutive

Question 25

For the gaseous reaction 2A -> B, where the feed consists of 50 mole % A and 50 mole % inerts, the expansion factor is

Answer 25

-0.25

Question 26

The molecularity and the order of reaction respectively, for the hydrolysis of methyl acetate in presence of acids are

Answer 26

2 & 1

Question 27

A pollutant P degrades according to first order kinetics. An aqueous stream containing P at 2 kmole/m3 and volumetric flow rate 1m3 /h requires a mixed flow reactor of volume V to bring down the pollutant level to 0.5 kmole/m3 . The inlet concentration of the pollutant is now doubled and the volumetric flow rate is tripled. If the pollutant level is to be brought down to the same level of 0.5 kmole/m3 , the volume of the mixed flow reactor should be increased by a factor of

Answer 27

7

Question 28

The knowledge of initial concentration and rate constant is necessary to determine the half life time of a reaction of __________ order.

Answer 28

second

Question 29

The synthesis of proteins and metabolism in biological objects occur in the presence of biocatalyst called

Answer 29

fungi

Question 30

In case of a __________ reactor, the composition in the reactor and at the exit of the reactor is the same.

Answer 30

back-mix

Question 31

Exothermic reactions are best carried out in

Answer 31

CSTR followed by a plug flow reactor.

Question 32

What is the order of chemical reaction  , if it is found that the reaction rate doubles on doubling the concentration of B and also the reaction rate doubles when the concentrations of both A & B were doubled and quandrupled when the concentrations of both B & C were doubled ?

Answer 32

2

Question 33

In case of a/an __________ chemical reaction, conversion increases with the rise in temperature.

Answer 33

reversible endothermic

Question 34

A space velocity of 5 hr^-1 means that

Answer 34

five reactor volumes of feed (at specified conditions) are being fed into the reactor per hour.

Question 35

With increase in initial concentration, the fractional conversion of a first order reaction in a given time

Answer 35

remains constant

Question 36

The rate of reaction of a/an __________ reaction is not affected by temperature rise.

Answer 36

photochemical

Question 37

With an increase in pressure in gaseous phase chemical reactions, the fractional conversion __________ when the number of moles decreases.

Answer 37

increases

Question 38

Half-life period for a first order reaction is __________ the initial concentration of the reactant.

Answer 38

independent of

Question 39

Carbon particles accummulated on the catalyst used in the gas oil cracking lies in the category of __________ poison.

Answer 39

deposited

Question 40

What is the dispersion number for a plug flow reactor ?

Answer 40

0

Question 41

The catalytic converter for conversion of SO2 to SO3 by contact process should have a feed with SO2 content between

Answer 41

7-10%

Question 42

With increase in K2/K1 in case of a unimolecular type elementary reactions, the fractional yield of 'R' in mixed reactor (for a given conversion of 'A')

Answer 42

decreases

Question 43

A gaseous reactant is introduced in a mixed reactor of 3 litres volume at the rate of 1 litre/second. The space time is __________ seconds.

Answer 43

1

Question 44

A liquid decomposes by irreversible first order kinetics and the half life period of this reaction is 8 minutes. The time required for 75% conversion of the liquid will be __________ minutes.

Answer 44

16

Question 45

If helium is introduced in a reactor containing O2, SO2 and SO3 at equilibrium, so that total pressure increases while volume and temperature remains constant. In this case the dissociation of SO3 (as per Le Chatlier principle)

Answer 45

decreases

Question 46

An isothermal aqueous phase reversible reaction, P  R, is to be carried out in a mixed flow reactor. The reaction rate in k.mole/m3 .h is given by, r = 0.5CP - 0.125CR. A stream containing only P enters the reactor. The residence time required (in hours) for 40% conversion of P is

Answer 46

1.60

Question 47

For a fluidised bed reactor, the most suitable/relevant model is a __________ model.

Answer 47

bubbling bed

Question 48

The rate at which a chemical substance reacts is proportional to its

Answer 48

Active mass

Question 49

In a reaction, the threshold energy is equal to (where, A = activation energy N = normal energy of reactants)

Answer 49

A+N

Question 50

The most suitable reactor for carrying out an auto-thermal reaction is a

Answer 50

CSTR

Question 51

Limiting reactant in a chemical reaction decides the

Answer 51

conversion

Question 52

The rate of forward reaction, at chemical equilibrium is____the rate of backward reaction.

Answer 52

equal to

Question 53

Enzymes (a protein) are catalysts found in organisms. Its efficiency of catalysing a reaction is due to its capacity to lower the activation energy of the reaction. The enzyme ptyalin used for food digestion is present in

Answer 53

saliva

Question 54

In the converter of the contact process for the manufacture of H2SO4 the equilibrium conversion of SO2 __________ (A) __________ with increase in temperature and __________ (B) __________ with increase in the mole ratio of SO2 to air.

Answer 54

(A) decreases (B) increases

Question 55

The time needed to achieve the same fractional conversion for particles of different sizes (d) when chemical reaction controls, is proportional to

Answer 55

d

Question 56

An exothermic reaction takes place in an adiabatic reactor. The product temperature __________ reactor feed temperature.

Answer 56

is always greater than

Question 57

The vessel dispersion number (D/μL) for plug flow is

Answer 57

0

Question 58

Carrier in a catalyst increases its

Answer 58

surface area

Question 59

When the reaction occurs in the diffusion controlled region, the apparent activation energy as measured is only __________ the true value.

Answer 59

half

Question 60

An isothermal irreversible reaction is being carried out in an ideal tubular flow reactor. The conversion in this case will __________ with decrease in space time.

Answer 60

decrease

Question 61

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

Answer 61

mixed

Question 62

Which of the following is an autocatalytic reaction ?

Answer 62

Microbial fermentation reaction

Question 63

Holding time for flow reactors is __________ the space time, for constant fluid density

Answer 63

equal to

Question 64

Thermodynamic equilibrium constant in a system is affected by

Answer 64

Temperature

Question 65

The order of the reaction, H2 + Cl2 (Sunlight) ---> 2HCL , is

Answer 65

0

Question 66

The catalyst in a first order chemical reaction changes the

Answer 66

activation energy

Question 67

Oil is hydrogenated using nickel catalyst in a __________ reactor.

Answer 67

slurry

Question 68

Reaction rate of a first order reaction, which is half completed in 23 minutes will be

Answer 68

0.03 min^-1