Chemical Reaction Engineering Flashcards
(145 cards)
1
Q
Which of the following will give maximum gas conversion ?
Fixed bed reactor.
Fluidised bed reactor.
Semi-fluidised bed reactor.
Plug-flow catalytic reactor.
A
Semi-fluidised bed reactor.
Combines advantages of fixed bed + fluidised bed reactors.
2
Q
__________ explains the mechanism of catalysis.
Activated complex theory
Collision theory
Thermodynamics
None of these
A
Activated complex theory
3
Q
From among the following, choose one which is not an exothermic process.
Methanol synthesis
Catalytic cracking
Ammonia synthesis
Oxidation of sulphur
A
Catalytic cracking
4
Q
The fractional volume change of the system for the isothermal gas phase reaction, A 3B , between no conversion and complete conversion is
0.5
1
2
3
A
2
5
Q
A catalyst _____.
initiates a reaction.
lowers the activation energy of reacting molecules.
is capable of reacting with any one of the reactants.
can not be recovered chemically unchanged at the end of a chemical reaction.
A
lowers the activation energy of reacting molecules.
6
Q
What is the order of a chemical reaction, A + 2B → K, if the rate of formation of ‘C’, increases by a factor of 2.82 on doubling the concentration of ‘A’ and increases by a factor of 9 on trebling the concentration of ‘B’?
7/2
7/4
5/2
5/4
A
7/2
7
Q
For high conversion in a highly exothermic solid catalysed reaction, use a __________ bed reactor.
fixed
fluidised bed reactor followed by a fixed
fixed bed reactor followed by a fluidised
fluidised
A
fluidised bed reactor followed by a fixed
8
Q
For every 10°C rise in temperature, the rate of chemical reaction doubles. When the temperature is increased from 30 to 70°C, the rate of reaction increases __________ times.
8
12
16
32
A
16
9
Q
The single parameter model proposed for describing non-ideal flow is the __________ model.
tank in series
dispersion
both (a) & (b)
neither (a) nor (b).
A
both (a) & (b)
10
Q
A first order reaction requires two equal sized CSTR. The conversion is
less when they are connected in series.
more when they are connected in series.
more when they are connected in parallel.
same whether they are connected in series or in parallel.
A
more when they are connected in series.
11
Q
In case of physical adsorption, the heat of adsorption is of the order of __________ kcal/kg.mole.
100
1000
10000
100000
A
1000
12
Q
The most unsuitable reactor for carrying out reactions in which high reactant concentration favours high yields is
backmix reactor
plug flow reactor
series of CSTR
PFR in series
A
backmix reactor
13
Q
Pick out the wrong statement pertaining to space velocity of flow reactors.
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.
The space velocity of 3 hr-1 means that one third reactor volume of feed at specified conditions are being fed into the reactor.
none of these.
A
The space velocity of 3 hr-1 means that one third reactor volume of feed at specified conditions are being fed into the reactor.
Space velocity should be feed rate.
14
Q
A reactor is generally termed as an autoclave, when it is a
high pressure batch reactor.
atmospheric pressure tank reactor.
high pressure tubular reactor.
atmospheric pressure CSTR.
A
high pressure batch reactor.
15
Q
6 gm of carbon is burnt with an amount of air containing 18 gm oxygen. The product contains 16.5 gms CO2 and 2.8 gms CO besides other constituents. What is the degree of conversion on the basis of disappearance of limiting reactant ?
100%
95%
75%
20%
A
95%
16
Q
The rate constant of a chemical reaction decreases by decreasing the
pressure
concentration of reactants
temperature
duration of reaction
A
temperature
17
Q
Reaction rate equation for the reaction, R + 2S → X = Y is -dCR/dt = KCRCS^2 . If S at is present in large excess, what is the order of this reaction?
zero
one
two
three
A
one
18
Q
Rate of a gaseous phase reaction is given by, -dpA/dt = Kp^2*A. The unit of rate constant is
(atm)-1
(hr)-1
(atm)-1.(hr)-1
atm.(hr)-1
A
(atm)-1.(hr)-1
19
Q
__________ is the response curve for a step input signal from a reactor.
S-curve
C-curve
I-curve
none of these
A
S-curve
20
Q
‘If the catalyst pore size is small in comparison with the mean free path, collisions with the pore wall controls the process’. The diffusivity under this condition is called ‘Knudsen diffusivity’, which is affected by the ____.
pressure
temperature
both (a) & (b)
neither (a) nor (b)
A
both (a) & (b)
T only. Mechanism is dependent on collision bw gas molecules.
21
Q
Which of the following is the most suitable for very high pressure gas phase reaction ?
Batch reactor
Tubular flow reactor
Stirred tank reactor
Fluidised bed reactor
A
Tubular flow reactor
22
Q
The reaction between oxygen and organic material is a/an __________ reaction.
exothermic
endothermic
biochemical
photochemical
A
exothermic
23
Q
With decrease in temperature, the equilibrium conversion of a reversible endother-mic reaction
decreases
increases
remains unaffected
increases linearly with temperature
A
decreases
24
Q
In an exothermic chemical reaction, the reactants compared to the products have
higher temperature
more energy
less energy
same energy.
A
more energy
25
In a consecutive reaction system A→B→C when E1 is much greater than E2, the yield of B increases with the _____.
increase of temperature.
decrease of temperature.
increase in initial concentration of A.
decrease in initial concentration of A.
increase of temperature.
26
A reversible liquid phase endothermic reaction is to be carried out in a plug flow reactor. For minimum reactor volume, it should be operated such that the temperature along the length
decreases.
increases.
is at the highest allowable temperature throughout.
first increases and then decreases.
is at the highest allowable temperature throughout.
27
The rate constant of a chemical reaction increases by 100 times when the temperature is increased from 400 °K to 500 °K. Assuming transition state theory is valid, the value of E/R is
8987°K
9210°K
8764°K
8621°K
9210°K
28
A batch reactor is suitable for
achieving cent percent conversion of reactants into products.
large scale gaseous phase reactions.
liquid phase reactions.
obtaining uniform polymerisation products in highly exothermic reactions.
liquid phase reactions.
29
For a heterogeneous catalytic reaction
free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction.
a relatively small amount of catalyst can cause the conversion of large amount of reactants which does not mean that catalyst concentration is important.
the catalyst does not form an intermediate complex with the reactant.
the surface of the catalyst does not play an important role during reaction.
free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction.
30
The increase in the rate of reaction with temperature is due to
increase in the number of effective collisions.
decrease in activation energy.
increase in the average kinetic energy of the reacting molecules.
none of these.
decrease in activation energy.
31
A catalyst loses its activity due to
loss in surface area of the active component.
agglomeration of metal particles caused by thermal sintering of the solid surface.
covering of the catalytic active sites by a foregin substance.
all (a), (b) and (c).
all (a), (b) and (c).
32
'N' plug flow reactors in series with a total volume 'V' gives the same conversion as a single plug flow reactor of volume 'V' for __________ order reactions.
first
second
third
any
any
33
For the irreversible elementary reactions in parallel viz K2: X→Y, K1: X→Z , the rate of disappearance of 'X' is equal to:
CA(K1+K2)
CA(K1 + K2)/2
CA . K1/2
CA . K2/2
CA(K1+K2)
34
For an isothermal variable volume batch reactor, the following relation is applicable for a first order irreversible reaction.
XA = k . t
(Ca0/1+𝛆AXA)(dXA/dt) = k
-ln(1 - XA) = kt
εA . ln (1 - XA) = k . t
(Ca0/1+𝛆AXA)(dXA/dt) = k
35
For a zero order chemical reaction, the
half life period is directly proportion to the initial concentration of the reac-tants.
plot of products concentration with time is a straight line through the origin.
products concentration increases linerarly with time.
all (a), (b) and (c).
all (a), (b) and (c).
36
BET apparatus
measures the catalyst surface area directly.
operates at very high pressure.
is made entirely of stainless steel.
none of these.
none of these.
does not measure SA directly, operates at low pressure, and contains glass or quartz.
37
Radioactive decay follows __________ order kinetics.
first
second
third
zero.
first
38
The excess energy of reactants in a chemical reaction required to dissociate into products is termed as the __________ energy.
activation
potential
binding
threshold
activation
39
For a solid catalysed chemical reaction, the effectiveness of solid catalyst depends upon the __________ adsorption.
physical
chemical
both (a) and (b)
neither (a) nor (b)
chemical
40
Pick out the correct statement.
In catalytic reactions, the catalyst reacts with the reactants.
A catalyst initiates a chemical reaction.
A catalyst lowers the activation energy of the reacting molecules.
A catalyst can not be recovered chemi cally unchanged at the end of the chemical reaction.
A catalyst lowers the activation energy of the reacting molecules.
41
The dimensions of rate constant for reaction 3A B are (l/gm mole)/min. Therefore the reaction order is
0
1
2
3
2
42
Pick out the correct statement
Reactions with high activation energies are very temperature sensitive.
Chemical equilibrium is a static state.
A photochemical reaction is catalysed by light.
A chemical reaction occurs when the energy of the reacting molecule is less than the activation energy of the reaction.
Reactions with high activation energies are very temperature sensitive.
43
If the time required to complete a definite fraction of reaction varies inversely as the concentration of the reactants, then the order of reaction is
0
1
2
3
2
44
Sulphuric acid is used as a catalyst in the
hydrogenation of oils.
gas phase oxidation of SO2 in chamber process.
alkylation of hydrocarbons.
none of these.
alkylation of hydrocarbons.
45
Fractional conversion __________ with increase in pressure for ammonia synthesis reaction i.e., N2 + 3H2 2NH3.
increases
decreases
remains unchanged
unpredictable from the data
increases
46
Pick out the wrong statement.
The vessel dispersion number (D/UL) for plug flow and mixed flow approaches zero and infinity respectively.
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.
Mixed reactor is always smaller than the plug flow reactor for all positive reaction orders for a particular duty.
In an ideal tubular flow reactor, mixing takes place in radial direction and there is no mixing in logitudinal direction.
Mixed reactor is always smaller than the plug flow reactor for all positive reaction orders for a particular duty.
It should be "MR is always larger the PFR"
47
The reason why a catalyst increases the rate of reaction is that, it
decreases the energy barrier for reaction.
increases the activation energy.
decreases the molecular collision diameter.
none of these.
decreases the energy barrier for reaction.
48
A first order irreversible reaction, A B is carried out separately in a constant volume as well as in a variable volume reactor for a particular period. It signifies that __________ in the two reactors.
both conversion as well as concentration are same
conversion in both will be the same but concentrations will be different
both the conversion as well as concentrations will be different
none of these.
conversion in both will be the same but concentrations will be different
49
When the density of the reaction mixture is constant in a chemical reaction, the ratio of the mean residence time to space time is
> 1
< 1
1
0
1
50
In an ideal tubular-flow reactor
there is no mixing in longitudinal direction.
mixing takes place in radial direction.
there is a uniform velocity across the radius.
all (a), (b) and (c).
all (a), (b) and (c).
51
At a given value of E/R (ratio of activation energy and gas constant), the ratio of the rate constants at 500°K and 400°K is 2, if Arrhenious law is used. What will be this ratio, if transition state theory is used with the same value of E/R?
1.6
2
2.24
2.5
2.5
52
_________ is the controlling step in a highly temperature sensitive fluid-solid non-catalytic reaction.
Gas film diffusion
Ash diffusion
Chemical reaction
none of these
Chemical reaction
53
An autothermal reactor is
most suitable for a second order reaction.
most suitable for a reversible reaction.
completely self-supporting in its thermal energy requirements.
isothermal in nature.
completely self-supporting in its thermal energy requirements.
54
The rate constant of a first order reaction depends on the _____.
concentration of the reactant.
temperature.
concentration of the product.
time.
temperature.
55
A reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.
catalytic
autocatalytic
photochemical
none of these
autocatalytic
56
The ratio of volume of mixed reactor to the volume of P.F.R. (for identical flow rate, feed composition and conversion) for zero order reaction is
∞
0
1
> 1
1
57
Which of the following will favour the reverse reaction in a chemical equilibrium reaction ?
Increasing the concentration of one of the reactants.
Increasing the concentration of one or more of the products.
Removal of at least one of the products at regular interval.
None of these.
Increasing the concentration of one or more of the products.
58
Conversion increases with increase in temperature in case of a an __________ reaction.
autocatalytic
irreversible
reversible endothermic
reversible exothermic
reversible endothermic
59
Effective diffusivity (DE) in a catalyst pellet is related to molecular diffusivity (DN) and Knudsen diffusivity (DK) as
DE = DM + DK
1/DE = 1/DN + 1/DK
DE = DM . DE
DE = DN/DE
1/DE = 1/DN + 1/DK
60
A photochemical reaction is __________ light.
initiated by
accompanied with emission of
catalysed by
used to convert heat energy into
initiated by
61
Pick out the wrong statement.
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 batchwise, while the other reactant is fed continuously.
In a continuous flow reactor, uniform concentration can not 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 continuous flow reactor, uniform concentration can not be maintained throughout the vessel even in a well agitated system.
62
In a/an __________ reactor, there is exchange of heat with the surroundings with sizeable temperature variation.
adiabatic
isothermal
non-adiabatic
none of these.
non-adiabatic
63
'Unreacted core model' represents the reaction involving _____.
combustion of coal particles.
roasting of sulphide ores.
manufacture of carbon disulphide from elements.
none of these.
roasting of sulphide ores.
64
For a vapour phase catalytic reaction (A + B P) which follows the Ridel mechanism and the reaction step is rate controlling, the rate of reaction is given by (reaction rate is irreversible, product also absorbs).
-rA = kPaPb/1+KaPa+KpPp
-rA = kPa2-k1Pp/1+KaPa+KpPp
-rA = kPaPb/1+KaPb+KbPbKpPp
-rA = kPaPb/1+KaPa
-rA = kPaPb/1+KaPa+KpPp
65
If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is the __________ diffusion.
film
ash layer
pore
none of these
film
66
The units of frequency factor in Arhenious equation
are the same as those of the rate constant.
depend on the order of the reaction.
depend on temperature, pressure etc. of the reaction.
are cycles per unit time.
are the same as those of the rate constant.
67
Which of the following is not a chemical step in a fluid solid catalytic reaction ?
Surface chemical reaction
Adsorption
Desorption
None of these
None of these
68
For a series of reactions A→(k1)B→(k2)C having k1 << k2, the reaction system can be approximated as
a. A→(k1)B
b. A→(k2)B
c. A→(k2)C
d. A→(k1)C
d. A→(k1)C
69
At a given temperature, K1, K2 and K3 are equilibrium constants for the following reactions 1, 2, 3 respectively.
CH4(g) + H2O(g) CO(g) + 3H2(g),
CO(g) + H2O(g) CO2(g) + H2(g)
CH4(g) + 2H2O(g) CO2(g) + 4H2(g)
Then K1, K2 and K3 are related as:
K3 = K1.K2
K3 = (K1.K2)^0.5
K3(K1+K2)/2
K3 = (K1.K2)^2
K3 = K1.K2
70
In case of __________ reactions, the reaction rate does not decrease appreciably as the reaction proceeds.
catalytic
parallel
series
auto catalytic
auto catalytic
71
For nearly isothermal operation involving large reaction time in a liquid-phase reaction, the most suitable reactor is a __________ reactor.
stirred tank
tubular flow
batch
fixed bed
stirred tank
72
What is the Thiele modulus of the solid catalysed first order reaction, , if the pore diffusion offers negligible resistance to reaction ?
< 5
< 0.5
> 1
5
< 0.5
73
B.E.T. method can be used to determine the __________ of a porous catalyst.
solid density
pore volume
surface area
all (a), (b) and (c)
surface area
74
Rate constant for a first order reaction does not depend upon reaction time, extent of reaction and the initial concentration of reactants ; but it is a function of reaction temperature. In a chemical reaction, the time required to reduce the concentration of reactant from 100 gm moles/litre to 50 gm moles/litre is same as that required to reduce it from 2 gm moles/litre to 1 gm mole/litre in the same volume. Then the order of this reaction is
0
1
2
3
1
75
Which of the following is an independent variable for a batch tank reactor with uniform concentration and temperature ?
Time
Useful volume of the tank
Diameter of the reactor
None of these
Time
76
For a gaseous phase reaction, rate of reaction is equal to K. CA . CB. If the volume of the reactor is suddenly reduced to l/4th of its initial volume, then the rate of reaction compared to the original rate will be __________ times.
8
16
1/8
1/16
16
77
In a reversible chemical reaction having two reactants in equilibrium, if the concentration of the reactants are doubled, then the equilibrium constant will
remain the same
be halved
also be. doubled
become one fourth
remain the same
78
The equilibrium constant of a catalytic chemical reaction __________ due to the presence of a catalyst.
increases
decreases
remains unaffected
unpredictable from the data
remains unaffected
79
The rate constant of a chemical reaction increases by increasing the
temperature
pressure
reactant's concentration
none of these
temperature
80
The catalytic activity of enzymes is due to their capacity to lower the __________ energy.
activation
potential
kinetic
none of these
activation
81
A first order reaction requires two unequal sized CSTR. Which of the following gives higher yield ?
Large reactor followed by smaller one.
Smaller reactor followed by larger one.
Either of the arrangement (a) or (b) will give the same yield.
Data insufficient, can't be predicted.
Either of the arrangement (a) or (b) will give the same yield.
82
Pick out the correct statement.
A lower temperature favours the reaction of lower activation energy.
The dispersion number for a reactor/vessel is uL/D.
The rate controlling step in a reaction involving many steps is the fastetst step.
Pore volume and porosity of a catalyst is measured by Brunaver-Emmet-Teller (BET) technique.
A lower temperature favours the reaction of lower activation energy.
83
The effect of increasing pressure on the gaseous equilibrium of the reaction 2X+3Y 3X+2Y indicates that ____.
pressure has no effect.
backward reaction is favoured.
forward reaction is favoured.
none of these.
pressure has no effect.
84
If in the gaseous phase reaction, N2O4 2NO2, x is the part of N2O4 which dissociates, then the number of molecules at equilibrium will be
(1 + x)
(1 - x)
(1 + x)2
(1 - x)2
(1 + x)
85
A batch reactor is characterised by ______.
constant residence time.
variation in extent of reaction and properties of the reaction mixture with time.
variation in reactor volume.
very low conversion.
variation in extent of reaction and properties of the reaction mixture with time.
86
When a catalyst increases the rate of forward reaction, the value of rate constant_____.
increases
decreases
remain same
becomes infinite
increases
87
Rate determining step in a reaction consisting of a number of steps in series is the __________ step.
fastest
slowest
intermediate
data insufficient; can't be predicted
slowest
88
The rate of a chemical reaction is almost doubled for every 10°C rise in temperature. The rate will increase __________ times, if the temperature rises form 10 to 100°C.
256
512
112
612
512
89
A catalyst in a chemical reaction __________ free energy change in the reaction.
increases
decreases
either (a) or (b); depends on the type of catalyst
neither (a) nor (b).
either (a) or (b); depends on the type of catalyst
90
Signal normally used to study non-ideal flow by stimulus response technique is __________ input.
pulse
step
both (a) & (b)
neither (a) nor (b).
both (a) & (b)
91
When all the limiting reactant is consumed in the reaction, the operational yield __________ the relative yield.
is greater than
is smaller than
equals
can be either greater or smaller than (depends on the type of reaction)
equals
92
The half life period of a first order reaction is
always the same irrespective of the reaction.
independent on initial concentration of the reactants.
proportional to the initial concentration of reactants.
half the specific rate constant.
independent on initial concentration of the reactants.
93
The catalyst in a second order reversible reaction increases the rate of the forward reaction ______.
and decreases that of backward reaction.
and backward reaction equally.
only.
to a greater extent than that of the backward reaction.
and backward reaction equally.
94
Catalyst carriers
have very high selectivity.
increase the activity of a catalyst.
provide large surface area with a small amount of active material.
inhibit catalyst poisoning.
provide large surface area with a small amount of active material.
95
For the liquid phase zero order irreversible reaction A B, the conversion of A in a CSTR is found to be 0.3 at a space velocity of 0.1min-1 . What will be the conversion for a PFR with a space velocity of 0.2 min-1? Assume that all the other operating conditions are the same for CSTR and PFR.
0.15
0.30
0.60
0.90
0.60
96
A high space velocity means that a given
reaction can be accomplished with small reactor.
conversion can be obtained with a high feed rate.
both (a) and (b).
none of these.
both (a) and (b).
97
In flow reactors, the performance equations interrelate the rate of reaction to the
feed rate.
reactor volume,
extent of reaction.
all (a), (b) and (c).
all (a), (b) and (c).
98
Space velocity
describes the extensive operating characteristics of a tubular flow reactor.
is the maximum feed rate pre unit volume of reactor for a given conversion.
is a measure of the ease of the reaction.
all (a), (b) and (c)
all (a), (b) and (c)
99
The rate of the chemical reaction A B doubles as the concentration of A i.e.., CA is doubled. If rate of reaction is proportional to CA^n, then what is the value of n for this reaction ?
0.5
1
0
2
1
100
A reaction which is catalysed by a base is catalysed by all substances which have a tendency to
lose a proton
gain a proton
gain an electron
none of these
gain a proton
101
For a homogeneous reaction of nth order, the dimension of the rate constant is given by
l/(time)n
(concentration)^(1 - n)/(time)
(concentration)^(n - 1)/(time)
none of these
(concentration)1 - n/(time)
102
The fractional volume change between no conversion and complete conversion, for the isothermal gas phase reaction, 2A R, is
0.5
-0.5
1
1.5
-0.5
103
The reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.
biochemical
photochemical
catalytic
autocatalytic
autocatalytic
104
A typical example of an exothermic reversible reaction conducted at high pressure in industry is
dehydration of ethanol.
methanol synthesis.
reformation of methane.
polymerisation of ethylene.
dehydration of ethanol.
105
Study of chemical kinetics is the easiest in the case of __________ reactions.
irreversible
reversible
surface
side
irreversible
106
In autocatalytic reactions,
one of the reactants acts as a catalyst.
one of the products acts as a catalyst.
catalysts have very high selectivity.
no catalyst is used.
one of the products acts as a catalyst.
107
Semibatch reactor is preferred, when a/an
a highly exothermic reaction is to be controlled.
undersirable side reaction (at high concentration of one of the reactants) is to be avoided.
a gas is to be reacted with liquid (e.g. hydrogenation of fat).
all (a), (b), and (c).
all (a), (b), and (c).
108
For identical flow rate, feed composition and for elementary first order reactions, 'N' equal sized mixed reactors in series with a total volume 'V' gives the same conversion as a single plug flow reactor of volume 'V' for constant density systems. This is true, when the value of 'N' is
1
>1
∞
≥1
∞
109
What is the order of a chemical reaction whose rate is deter-mined by the variation of one concentration term only ?
zero
first
second
third
first
110
Pick out the wrong statement.
Visible radiation provides the necessary activation energy in photochemical reactions.
The order and molecularity of a complex reaction may not be the same.
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.
The order and molecularity of a complex reaction may not be the same.
111
The rate at which a chemical substance reacts is proportional to its
active mass
equivalent weight
molecular weight
none of these
active mass
112
The exit age distribution of a fluid leaving a vessel (denoted by E) is used to study the extent of non-ideal flow in the vessel. The value of ∫Edt,0,∞ is
0
1
∞
√2π
1
113
A plug-flow reactor is characterised by
high capacity.
presence of axial mixing.
presence of lateral mixing.
constant composition and temperature of reaction mixture.
presence of lateral mixing.
114
Three plug flow reactors (PFR's) of 4, 5 & 6 m3 volumes are arranged in two branches as shown below in the figure.
If the total feed rate is 300 tons/hr, then for the same conversion in each branch, the feed rate through branch II should be __________ tons/hr.
100
150
200
225
100
115
For a tubular reactor with space time 'τ' and residence time 'θ', the following statement holds good.
τ and θ are always equal.
τ = θ , when the fluid density changes in the reactor.
τ = θ , for an isothermic tubular reactor in which the density of the process fluid is constant.
τ = θ , for a non-isothermal reactor.
τ = θ , for an isothermic tubular reactor in which the density of the process fluid is constant.
116
Rate of an autocatalytic chemical reaction is a function of
temperature only.
pressure only.
composition only.
all (a), (b) and (c).
all (a), (b) and (c).
117
Which of the following curves shows the effect of temperature on the extent of gas-solid adsorption at a given pressure ?
Langmuir adsorption isotherm
Adsorption isobar
Freundlich adsorption isotherm
None of these
Adsorption isobar
118
For an ideal mixed flow reactor (CSTR), the exit age distribution E(t) is given by
a dirac delta function
a step function.
a ramp function.
none of the above
none of the above
It should be an exponential function.
E(t) = e^(-t/τ)
119
Fluid flow in a real packed bed can be approximated as __________ model.
plug flow
dispersion
mixed flow
tank in series
dispersion
120
The 'E' curve for a non-ideal reactor defines the fraction of fluid having age between t and t + dt
at the inlet
at the outlet
in the reactor
averaged over the inlet and outlet
at the outlet
121
To maximise the formation of R in the simultaneous reaction
A + B R , rR = 2CA0.5.CB2
A + B S , rS = 1.5 CA . CB
We should have
low CA, low CB
low CA, high CB
high CA, low CB
high CA, high CB
low CA, high CB
122
A reaction which is catalysed by an acid is also catalysed by any substance, which has a tendency to
lose a proton.
gain a proton.
lose an electron
none of these.
lose a proton.
123
A stirred tank reactor compared to tubular-flow reactor provides
more uniform operating conditions.
permits operation at the optimum temperature for a long reaction time.
higher overall selectivity for a first order consecutive reaction.
all (a), (b) and (c)
all (a), (b) and (c)
124
A chemical reaction, A ➡️ 3B, is conducted in a constant pressure vessel. Starting with pure A, the volume of the reaction mixture increases 3 times in 6 minutes. The fractional conversion is
0.33
0.5
1
data insufficient, can't be predicted
1
125
A catalyst inhibitor
lessens its selectivity.
may be useful for suppressing undesirable side reactions.
is added in small quantity during the catalyst manufacture itself.
all(a), (b) and (c).
all(a), (b) and (c).
126
In chamber process of sulphuric acid manufacture in industry, the gas phase oxidation of SO2 to SO3 is accomplished by a __________ reaction.
non-catalytic homogeneous
non-catalytic heterogeneous
catalytic homogenous
catalytic heterogeneous
catalytic homogenous
127
If the rate of a chemical reaction becomes slower at a given temperature, then the
initial concentration of the reactants remains constant.
free energy of activation is lower.
entropy changes.
free energy of activation is higher.
free energy of activation is higher.
128
The conversion XA and residence time data are collected for zero order liquid phase reaction in a stirred tank reactor. Which of the following will be a straight line ?
XA Vs . τ
XA Vs ln τ
XA/(1 - XA)Vs τ
XA(1 - XA)Vs τ
XA Vs . τ
129
The rate of the reaction, X → Y, quadruples when the concentration of 'X' is doubled. The rate expression for the reaction is, r = K Cx^n, the value of 'n' in this case will be
0
1
2
3
2
130
The value of steric factor 'P' in the equation k = PZeE/RT usually ranges from
l.0 to 10-8
l.l.to 102
0.1 to 0.9
none of these
l.0 to 10-8
131
For a zero order reaction, the concentration of product increases with the
increase of reaction time.
increase in initial concentration.
total pressure.
decrease in total pressure.
increase of reaction time.
132
Pick out the wrong statement.
'Hold back' is defined as the fraction of material that stays longer than the mean residence time.
Study of non-ideal flow reactor is done experimentally by stimulus-response technique.
For studying a chemical reaction, it is desirable to monitor the reactants during initial stages and the products during the final stages of reaction.
A batch reactor can not be used to study the kinetics of catalytic reaction.
A batch reactor can not be used to study the kinetics of catalytic reaction.
133
Effectiveness factor of a catalyst pellet is a measure of the __________ resistance.
pore diffusion
gas film
chemical reaction
none of these
pore diffusion
134
The rate expression for a heterogenous catalytic reaction is given by, - rA = K.KA PA(1 + KA.PA + KR.PR), where K is surface reaction rate constant and KA and KR are absorption equilibrium constants of A and R respectively. If KR PR >> (1 + KA PA), the apparent activation energy EA is equal to (given E is the activation energy for the reaction and ΔHR and ΔHA are the activation energies of adsorption of R and A)
E
E + ΔHA
E + ΔHA - ΔHR)
ΔHA + ΔHR
E + ΔHA - ΔHR)
135
Given,
3H2 + CO = CH4 + H2O, KP = 101.84 and,
4H2 + CO2 = CH4 + 2H2O, KP = 101.17
the KP for the reaction CO + H2O = CO2 + H2 is
10^3.01
10^-0.67
10^-3.01
10^0.67
10^0.67
136
Differential method for analysing the kinetic data is used
for testing complicated mechanisms.
when the data are scattered.
when rate expressions are very simple.
none of these.
for testing complicated mechanisms.
137
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
more
less
same
either (a) or (b), depends on other factors
same
138
The reaction in which the rate equation corresponds to a stoichiometric equation, is called a/an __________ reaction.
elementary
non-elementary
parallel
autokinetic
elementary
139
The reaction A B is conducted in an isothermal batch reactor. If the conversion of A increases linearly with holding time, then the order of the reaction is
0
1
1.5
2
0
140
A first order gaseous phase reaction is catalysed by a non-porous solid. The kinetic rate constant and the external mass transfer co-efficients are k and kg respectively. The effective rate constant (keff) is given by
keff = k + kg
keff = (k+ kg)/2
keff = (kkg)1/2
1/keff = 1/k + 1/kg
1/keff = 1/k + 1/kg
141
Arrhenious equation represents graphically the variation between the __________ and temperature.
rate of reaction
frequency factor
rate constant
activation energy
rate constant
142
__________ catalytic reaction is involved in the thermal cracking of gas oil.
Homogeneous
Homogeneous non
Heterogeneous
Heterogeneous non
Homogeneous
143
Variables affecting the rate of homogeneous reactions are
pressure and temperature only.
temperature and composition only.
pressure and composition only.
pressure, temperature and composition.
pressure, temperature and composition.
144
A chemical reaction occurs when the energy of the reacting molecules is __________ the activation energy of the reaction.
less than
equal to
more than
equal to or more than
equal to or more than
145
