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Day 2 > Chemical Reaction Engineering > Flashcards

Chemical Reaction Engineering Flashcards

1
Q

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

A

75%

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2
Q

What is the dispersion number for a CSTR?

A

∞

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3
Q

Bulk diffusion in catalyst pore __________ with increase in pressure.

A

decreases

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4
Q

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

A

exponentially with time.

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5
Q

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

A

equal to or more than

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6
Q

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

A

0.144

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7
Q

The residence time distribution of an ideal CSTR is

A

exp(-t/τ)

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8
Q

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

A

zymase

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9
Q

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

A

0.875

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10
Q

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

A

more

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11
Q

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 ?

A

1/2

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12
Q

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

A

CB0≥CB0

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13
Q

Inversion of cane sugar is an example of

A

bimolecular reaction with first order.

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14
Q

Pressure changes do not change the equilibrium concentrations.

A

correctuee

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15
Q

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.

A

16

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16
Q

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.

A

proportional to

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17
Q

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

A

Ash

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18
Q

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

A

Langmuir

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19
Q

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

A

dead zone

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20
Q

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

A

much lower

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21
Q

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

A

diffusion within the pellet.

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22
Q

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

A

1.5

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23
Q

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)

A

increases

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24
Q

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

A

consecutive

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25
Q

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

A

-0.25

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26
Q

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

A

2 & 1

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27
Q

A pollutantPdegrades according to first order kinetics. An aqueous stream containingPat 2 kmole/m3and 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

A

7

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28
Q

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

A

second

29
Q

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

A

fungi

30
Q

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

A

back-mix

31
Q

Exothermic reactions are best carried out in

A

CSTR followed by a plug flow reactor.

32
Q

What is the order of chemical reaction, if it is found that the reaction rate doubles on doubling the concentration ofBand also the reaction rate doubles when the concentrations of bothA&Bwere doubled and quandrupled when the concentrations of bothB&Cwere doubled ?

A

2

33
Q

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

A

reversible endothermic

34
Q

A space velocity of 5 hr^-1means that

A

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

35
Q

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

A

remains constant

36
Q

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

A

photochemical

37
Q

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

A

increases

38
Q

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

A

independent of

39
Q

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

A

deposited

40
Q

What is the dispersion number for a plug flow reactor ?

A

0

41
Q

The catalytic converter for conversion of SO2to SO3by contact process should have a feed with SO2content between

A

7-10%

42
Q

With increase inK2/K1in case of a unimolecular type elementary reactions, the fractional yield of ‘R’ in mixed reactor (for a given conversion of ‘A’)

A

decreases

43
Q

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.

A

1

44
Q

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.

A

16

45
Q

If helium is introduced in a reactor containing O2, SO2and SO3at equilibrium, so that total pressure increases while volume and temperature remains constant. In this case the dissociation of SO3(as per Le Chatlier principle)

A

decreases

46
Q

An isothermal aqueous phase reversible reaction,PR, 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 onlyPenters the reactor. The residence time required (in hours) for 40% conversion ofPis

A

1.60

47
Q

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

A

bubbling bed

48
Q

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

A

Active mass

49
Q

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

A

A+N

50
Q

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

A

CSTR

51
Q

Limiting reactant in a chemical reaction decides the

A

conversion

52
Q

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

A

equal to

53
Q

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 enzymeptyalinused for food digestion is present in

A

saliva

54
Q

In the converter of the contact process for the manufacture of H2SO4the equilibrium conversion of SO2__________ (A) __________ with increase in temperature and __________ (B) __________ with increase in the mole ratio of SO2to air.

A

(A) decreases (B) increases

55
Q

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

A

d

56
Q

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

A

is always greater than

57
Q

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

A

0

58
Q

Carrier in a catalyst increases its

A

surface area

59
Q

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

A

half

60
Q

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.

A

decrease

61
Q

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

A

mixed

62
Q

Which of the following is an autocatalytic reaction ?

A

Microbial fermentation reaction

63
Q

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

A

equal to

64
Q

Thermodynamic equilibrium constant in a system is affected by

A

Temperature

65
Q

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

A

0

66
Q

The catalyst in a first order chemical reaction changes the

A

activation energy

67
Q

Oil is hydrogenated using nickel catalyst in a __________ reactor.

A

slurry

68
Q

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

A

0.03 min^-1

69
Q
A

Day 2 (7 decks)

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