Chemical Reaction Flashcards
1
Q
Which of the following will give maximum gas conversion?
A
Semi-fluidised bed reactor.
2
Q
__________ explains the mechanism of catalysis.
A
Activated complex theory
3
Q
From among the following, choose one which is not an exothermic process.
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
A
2
5
Q
A catalyst
A
lowers the activation energy of reacting molecules.
6
Q
What is the order of a chemical reaction, https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/450-191-1.png , 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’?
A
45840
7
Q
For high conversion in a highly exothermic solid catalysed reaction, use a __________ bed reactor.
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.
A
16
9
Q
A first order reaction requires two equal sized CSTR. The conversion is
A
more when they are connected in series.
10
Q
In case of physical adsorption, the heat of adsorption is of the order of __________ kcal/kg.mole.
A
1000
11
Q
The most unsuitable reactor for carrying out reactions in which high reactant concentration favours high yields is
A
backmix reactor
12
Q
Pick out the wrong statement pertaining to space velocity of flow reactors.
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.
13
Q
A reactor is generally termed as an autoclave, when it is a
A
high pressure batch reactor.
14
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 ?
A
0.95
15
Q
The rate constant of a chemical reaction decreases by decreasing the
A
temperature
16
Q
Reaction rate equation for the reaction, https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/448-153-1.png . If S at is present in large excess, what is the order of this reaction?
A
one
17
Q
Rate of a gaseous phase reaction is given by, https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/460-311-1.png . The unit of rate constant is
A
(atm)-1.(hr)-1
18
Q
__________ is the response curve for a step input signal from a reactor.
A
S-curve
19
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
A
temperature
20
Q
Which of the following is the most suitable for very high pressure gas phase reaction ?
A
Tubular flow reactor
21
Q
The reaction between oxygen and organic material is a/an __________ reaction.
A
exothermic
22
Q
With decrease in temperature, the equilibrium conversion of a reversible endother-mic reaction
A
decreases
23
Q
In an exothermic chemical reaction, the reactants compared to the products have
A
more energy
24
Q
For a reaction of the type, https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/458-286-1.png , the rate of reaction (- rx) is given by
A
K1CV - K2CX
25
In a consecutive reaction system https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/446-134-1.png when E1 is much greater than E2, the yield of B increases with the
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
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
9210°K
28
A batch reactor is suitable for
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.
30
The increase in the rate of reaction with temperature is due to
decrease in activation energy.
31
A catalyst loses its activity due to
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.
any
33
For the irreversible elementary reactions in parallel viz https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/455-247-1.png , the rate of disappearance of 'X' is equal to
CA(K1+K2)
34
For an isothermal variable volume batch reactor, the following relation is applicable for a first order irreversible reaction.
CAo/(1+εAXA)(dXA/dt) = k
35
For a zero order chemical reaction, the
all (a), (b) and (c).
36
BET apparatus
none of these.
37
Radioactive decay follows __________ order kinetics.
first
38
The excess energy of reactants in a chemical reaction required to dissociate into products is termed as the __________ energy.
activation
39
For a solid catalysed chemical reaction, the effectiveness of solid catalyst depends upon the __________ adsorption.
chemical
40
Pick out the correct statement.
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
2
42
Pick out the correct statement
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
2
44
Sulphuric acid is used as a catalyst in the
alkylation of hydrocarbons.
45
Fractional conversion __________ with increase in pressure for ammonia synthesis reaction i.e., N2 + 3H2 <->2NH3.
increases
46
Pick out the wrong statement.
Mixed reactor is always smaller than the plug flow reactor for all positive reaction orders for a particular duty.
47
The reason why a catalyst increases the rate of reaction is that, it
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.
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
50
In an ideal tubular-flow reactor
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?
2.5
52
__________ is the controlling step in a highly temperature sensitive fluid-solid non-catalytic reaction.
Chemical reaction
53
An autothermal reactor is
completely self-supporting in its thermal energy requirements.
54
The rate constant of a first order reaction depends on the
temperature.
55
A reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.
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
1
57
Which of the following will favour the reverse reaction in a chemical equilibrium reaction ?
Increasing the concentration of one or more of the products.
58
Conversion increases with increase in temperature in case of a an __________ reaction.
reversible endothermic
59
Effective diffusivity (DE) in a catalyst pellet is related to molecular diffusivity (DN) and Knudsen diffusivity (DK) as
1/DE = 1/DN + 1/DK
60
A photochemical reaction is __________ light.
initiated by
61
Pick out the wrong statement.
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.
non-adiabatic
63
Unreacted core model' represents the reaction involving
roasting of sulphide ores.
64
If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is the __________ diffusion.
film
65
The units of frequency factor in Arhenious equation
are the same as those of the rate constant.
66
Which of the following is not a chemical step in a fluid solid catalytic reaction ?
None of these
67
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
68
In case of __________ reactions, the reaction rate does not decrease appreciably as the reaction proceeds.
auto catalytic
69
For nearly isothermal operation involving large reaction time in a liquid-phase reaction, the most suitable reactor is a __________ reactor.
stirred tank
70
What is the Thiele modulus of the solid catalysed first order reaction, https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/448-154-1.png , if the pore diffusion offers negligible resistance to reaction ?
< 0.5
71
B.E.T. method can be used to determine the __________ of a porous catalyst.
surface area
72
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
1
73
Which of the following is an independent variable for a batch tank reactor with uniform concentration and temperature?
Time
74
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.
16
75
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
76
The equilibrium constant of a catalytic chemical reaction __________ due to the presence of a catalyst.
remains unaffected
77
The rate constant of a chemical reaction increases by increasing the
temperature
78
The catalytic activity of enzymes is due to their capacity to lower the __________ energy.
activation
79
A first order reaction requires two unequal sized CSTR. Which of the following gives higher yield ?
Either of the arrangement (a) or (b) will give the same yield.
80
Pick out the correct statement.
A lower temperature favours the reaction of lower activation energy.
81
The effect of increasing pressure on the gaseous equilibrium of the reaction 2X+3Y <-->3X+2Y indicates that
pressure has no effect.
82
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)
83
A batch reactor is characterised by
variation in extent of reaction and properties of the reaction mixture with time.
84
When a catalyst increases the rate of forward reaction, the value of rate constant
increases
85
Rate determining step in a reaction consisting of a number of steps in series is the __________ step.
slowest
86
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.
512
87
A catalyst in a chemical reaction __________ free energy change in the reaction.
either (a) or (b); depends on the type of catalyst
88
When all the limiting reactant is consumed in the reaction, the operational yield __________ the relative yield.
equals
89
The half life period of a first order reaction is
independent on initial concentration of the reactants.
90
The catalyst in a second order reversible reaction increases the rate of the forward reaction
and backward reaction equally.
91
Catalyst carriers
provide large surface area with a small amount of active material.
92
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.
0.6
93
A high space velocity means that a given
both (a) and (b).
94
In flow reactors, the performance equations interrelate the rate of reaction to the
all (a), (b) and (c).
95
Space velocity
all (a), (b) and (c)
96
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 CAn, then what is the value of n for this reaction ?
1
97
A reaction which is catalysed by a base is catalysed by all substances which have a tendency to
gain a proton
98
For a homogeneous reaction of nth order, the dimension of the rate constant is given by
(concentration)^1 - n/(time)
99
The fractional volume change between no conversion and complete conversion, for the isothermal gas phase reaction, 2A-->R, is
-0.5
100
The reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.
autocatalytic
101
A typical example of an exothermic reversible reaction conducted at high pressure in industry is
dehydration of ethanol.
102
Study of chemical kinetics is the easiest in the case of __________ reactions.
irreversible
103
In autocatalytic reactions,
one of the products acts as a catalyst.
104
Semibatch reactor is preferred, when a/an
all (a), (b), and (c).
105
Exposure of a photographic plate to produce a latent image is an example of __________ reaction.
both (b) and (c)
106
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
∞
107
Helium-mercury method is used for the measurement of the __________ of the catalyst.
both (b) & (c).
108
What is the order of a chemical reaction whose rate is deter-mined by the variation of one concentration term only?
first
109
Pick out the wrong statement.
The order and molecularity of a complex reaction may not be the same.
110
The rate at which a chemical substance reacts is proportional to its
active mass
111
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 https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/467-387-1.png is
1
112
A plug-flow reactor is characterised by
presence of lateral mixing.
113
Three plug flow reactors (PFR's) of 4, 5 & 6 m3 volumes are arranged in two branches as shown below in the figure. https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/468-389-1.png 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
114
For a tubular reactor with space time 'τ' and residence time 'θ', the following statement holds good.
τ = θ , for an isothermic tubular reactor in which the density of the process fluid is constant.
115
Rate of an autocatalytic chemical reaction is a function of
all (a), (b) and (c).
116
Which of the following curves shows the effect of temperature on the extent of gas-solid adsorption at a given pressure?
Adsorption isobar
117
For an ideal mixed flow reactor (CSTR), the exit age distribution E(t) is given by
none of the above
118
Fluid flow in a real packed bed can be approximated as __________ model.
dispersion
119
For series reaction, the relative yield
both (a) and (c) hold good.
120
The 'E' curve for a non-ideal reactor defines the fraction of fluid having age between t and t + dt
at the outlet
121
To maximise the formation of R in the simultaneous reaction
A + B --> R , rR = 2CA^0.5.CB^2
A + B --> S , rS = 1.5 CA . CB
We should have
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.
123
A stirred tank reactor compared to tubular-flow reactor provides
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
1
125
A catalyst inhibitor
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.
catalytic homogenous
127
If the rate of a chemical reaction becomes slower at a given temperature, then the
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
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
2
130
The value of steric factor 'P' in the equation k = PZe^E/RT usually ranges from
1.0 to 10^-8
131
For a zero order reaction, the concentration of product increases with the
increase of reaction time.
132
Pick out the wrong statement.
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
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 + 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
10^0.67
136
Differential method for analysing the kinetic data is used
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
same
138
The reaction in which the rate equation corresponds to a stoichiometric equation, is called a/an __________ reaction.
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
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
1/keff = 1/k + 1/kg
141
Arrhenious equation represents graphically the variation between the __________ and temperature.
rate constant
142
__________ catalytic reaction is involved in the thermal cracking of gas oil.
Homogeneous
143
Variables affecting the rate of homogeneous reactions are
pressure, temperature and composition.
144
A chemical reaction occurs when the energy of the reacting molecules is __________ the activation energy of the reaction.
equal to or more than
145
Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction?
Ash resistance.
146
If the time required to change the concentration of reactant to half its original value is independent of the initial concentration, the order of reaction is
one
147
A batch adiabatic reactor at an initial temperature of 373°K is being used for the reaction, A-->B. Assume the heat of reaction is - 1kJ/mole at 373°K and heat capacity of both A and B to be constant and equal to 50J/mole.K. The temperature rise after a conversion of 0.5 will be
10°C
148
If CA is the quantity of reactants initially present, the quantity left after 'n' half periods will be equal to
(1/2)^n.CA
149
A photochemical reaction is
initiated by light.
150
The optimum performance for reactors operating in parallel is obtained when the feed stream is distributed in such a way, that the
space time for each parallel line is same.
151
A catalyst is said to be a negative catalyst, ifit
retards the rate of reaction.
152
For the non catalytic reaction of particles with surrounding fluid, the same needed to achive the same fractional conversion for particles of different unchanging sizes is proportional to the particle diameter, when the __________ is the controlling resistance.
chemical reaction
153
Pure ethanol vapor is fed to a reactor packed with alumina catalyst, at the rate of 100 kmole / hr. The reactor products comprise: ethylene :95 kmole / hr, water vapour: 97.5 k mole / hr and diethyl ether :2.5 kmole/hr. The reactions occuring can be represented by:
C2H5OH C2H4 + H2O
2C2H5OH C2H5 - O - C2H5 + H2O
The percent conversion of ethanol in the reactor is
100
154
Pick out the wrong statement.
When the reaction rate is independent of temperature, the reaction is said to be of zero order.
155
A backmix reactor
is same as ideal stirred tank reactor.
156
Rate of a chemical reaction is not influenced by the
number of molecules of reactants taking part in a reaction
157
Pick out the wrong statement:
The residence time for all the elements of fluid in case of a P.F.R. need not be same.
158
The reaction A B is conducted in an adiabatic plug flow reactor (PFR). Pure A at a concentration of 2 kmol/m3 is fed to the reactor at the rate of 0.01 m3 /s and at a temperature of 500 K. If the exit conversion is 20%, then the exit temperature (in k)is (Data: Heat of reaction at 298 K = - 50000 kJ/ kmole of A reacted Heat capacities CPA = CPB = 100kJ/kmole. K (may be assumed to be independent of temperature))
600
159
Which of the following is not a theory of homogeneous reaction?
None of these
160
A first order homogeneous reaction of the type X Y Z (consecutive reaction) is carried out in a CSTR. Which of the following curves respectively show the variation of the concentration of X, Y and Z with time? https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/446-129-1.png
III, II, I
161
In a semi-batch reactor,
velocity of reaction can be controlled.
162
Most important characteristics of gas-liquid reactors are the
both (a) and (b)
163
Which of the following is a controlling factor in very fast heterogeneous reaction?
Heat and mass transfer effects
164
Enzymes are destroyed, when the
temperature is very high,
165
For an autocatalytic reactor, the suitable reactor set up is
CSTR followed by P.F. reactor.
166
Ionic reactions occur in
solutions
167
Sometimes, batch process is preferred over continuous process, when the product
both (a) & (b).
168
In a chemical reaction https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/454-240-1.png , it is observed that the
(i) rate of formation of 'P' is doubled on doubling the concentration of 'X'.
(ii) rate of formation of 'P' is quadrupled on doubling the concentration of 'Y'.
(iii) doubling the concentration of 'Z' does not affect the rate of formation of 'P'.
What is the order of the above chemical reaction?
Third order
169
The half life period of a first order reaction is given by (where, K = rate constant. )
0.693/K
170
Half life period of a chemical reaction is
the time required to reduce the concentration of the reacting substance to half its initial value.
171
In the gaseous phase ammonia formation reaction (N2 + 3H2<-->2NH3), the value of the equilibrium constant depends on the
temperature.
172
Transition state theory relates the above quantities as
k ∝ T.e^E/RT
173
Photochemical reaction rate does not depend significantly on temperature, because
the energy of reacting molecules exceeds the activation energy by absorption of light.
174
A CSTR is to be designed in which an exothermic liquid phase first order reaction of the type, A-->R, is taking place. The reactor is to be provided with a jacket in which coolant is flowing. Following data is given: CA0= 5 kmole/m3 ; XA = 0.5; Feed temperature = reactor temperature = 40°C. Rate constant at 40°C = 1 min-1 ; (ΔH) = - 40kJ/mole; ρ = 1000kg/m3 CP = 4 J/gm.°C ; q = 10-3 m3/min (ρ and CP are same for the reactant and product streams). The amount of heat to be removed is
5/3 kW
175
According to the 'law of mass action', the rate of reaction is directly proportional to the
molar concentration of the reactants.
176
In a chemical reaction, __________ are conserved.
both(b) & (c)
177
For an ideal gas mixture undergoing a reversible gaseous phase chemical reaction, the equilibrium constant
increases with pressure.
178
In the reversible reaction of the type, A + B <--> AB, in general
the combination reaction will be exothermic, while the dissociation reaction will be endothermic.
179
A batch reactor is
suitable for liquid phase reactions involving small production rate.
180
For a first order reaction carried out in a plug flow reactor, the space time is
1/K ln Co/C
181
For an isothermal second order aqueous phase reaction, A --> B, the ratio of the time required for 90% conversion to the time required for 45% conversion is
11
182
A chemical reaction is of zero order, when the reaction rate is (where, CA = concentration of reactant)
none of these.
183
Second order consecutive irreversible reactions https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/473-457-1.png were carried out in a constant volume isothermal batch reactor with different initial feed compositions. Reactor temperature was same in all the cases. In experiments where the ratio of concentration of B to that of A in the initial feed was less than 0.5, the concentration of B increased first, reached a maximum and then declined with time. However, for all experiments where this concentration ratio was 0.5 or above, concentration of B decreased monotonically with time right from the beginning. What is the ratio of the two rate constants (k1/k2)?
45661
184
Pick out the wrong statement.
Enzymes help in increasing the activation energy of the reaction.
185
There is no correspondence between stoichiometry and the rate equation in case of a/an __________ reaction.
non-elementary
186
A spherical porous catalyst particle of radius R is subjected to reactant A which reacts to form B by a zero order surface reaction A B. Film mass transfer resistance is negligible and pore diffusion of A is rate controlling. The effectiveness factor of the catalyst is reported as 7/8. Which of the following statement is true?
Inner catalyst core of radius R/8 does not participate in reaction.
187
Which of the following is used for calcination of limestone and dolomite in industrial practice ?
Moving bed reactor
188
An imbalanced chemical reaction equation is against the law of
conservation of mass
189
For the chemical reaction P Q, it is found that the rate of reaction doubles as the concentration of 'P' is doubled. If the reaction rate is proportional to Cpn, then what is the value of 'n' for this chemical reaction ?
1
190
Which of the following is a characteristic of an ideal plug flow reactor ?
Flat velocity profile
191
Velocity of a reaction depends upon the
all (a), (b) and (c).
192
Threshold energy in a reaction is equal to the
sum of (a) & (b)
193
Arhenious equation shows the variation of __________ with temperature.
rate constant
194
When a catalyst increases the rate of chemical reaction, the rate constant
increases
195
In which of the following reactions, the equilibrium will shift to the right, if the total pressure is increased?
N2 + O2 <--> 2NO
196
The catalyst in a first order chemical reaction changes the
activation energy
197
Oil is hydrogenated using nickel catalyst in a __________ reactor.
slurry
198
The performance equations for constant density systems are identical for
P.F.R. and batch reactor.
199
Reaction rate of a first order reaction, which is half completed in 23 minutes will be
0.03 min-1
200
Which of the following is the optimum operating condition for an exothermic reversible reaction taking place in a plug-flow reactor ?
Temperature should be high in the beginning and decreased towards the end of the reaction.
201
In case of calcination of limestone, CaCO3 CaO + CO2, the addition of more of CaO will result in __________ in the concentration of CO2.
no change
202
The rate of a homogeneous reaction is a function of
all temperature, pressure and composition.
203
In the fluid catalytic cracker (FCC), the cracking reaction is __________ (A) and the regeneration is___(B) __________
(A) endothermic (B) exothermic
204
Pick out the correct statement.
A catalyst does not change AH of the reaction.
205
Promoter is added to the catalyst to improve its
sensitivity
206
An irreversible first order reaction is being carried out in a CSTR and PFR of same volume. The liquid flow rates are same. The relative conversion will
be more in PFR than in CSTR.
207
When a high liquid hold up is required in a reactor for gas liquid reaction, use __________ coloumn.
bubble
208
In an exothermic reaction, the energy of the reacting substances as compared to that of products is
more
209
For a tubular flow reactor with uniform concentration and temperature, the independent variable is
length
210
Pick out the wrong statement.
For a first order consecutive reaction, a tubular flow reactor as compared to a stirred tank reactor provides higher overall selectivity.
211
The extent of a reaction is
all of the above.
212
Higher free energy of activation of a chemical reaction (at a given temperature) implies
slower rate of reaction.
213
Calcination reaction of limestone (CaCO3 --> CaO + CO2) goes to completion in the rotary kiln, because
CO2 escapes continuously.
214
The reactions with low activation energy are
fast
215
Molecularity of an elementary reaction, P + Q --> R + S is
4
216
Which of the following is not endothermic in nature ?
Combustion of sulphur.
217
The space time is equivalent to the holding time in a steady state mixed reactor for
constant fluid density systems.
218
The dispersion number of perfect mixed flow is
∞
219
An irreversible aqueous phase reaction, A + B --> P, is carried out in an adiabatic mixed flow reactor. A feed containing 4kmole/m3 of each A and B enters the reactor at 8m3 /hr. If the temperature of the exit stream is never to exceed 390 K, what is the maximum inlet feed temperature allowed?
Data: Heat of reaction = - 50 kJ/mole
Density of the reacting mixture = 1000kg/m3
Specific heat of reacting mixture = 2kJ/kg.K
The above data can be assumed to be independent of temperature and composition.
290
220
For a heterogenous catalytic reaction, A + B --> C, with equimole feed of A and B, the initial rate - rA0 is invariant with total pressure. The rate controlling step is
desorption of C.
221
Half life period of a first order irreversible reaction A B is
ln 2/k
222
Pick out the wrong statement.
Hydrolysis of ester in presence of alkali or acid is a zero order reaction.
223
Which of the following is not a dimension-less group used in catalysis ? (where, D = dispersion co-efficient, cm2 /sec.D1 = diffusion co-efficient; cm2/sec L = length of the reactor, cm t = time, sec, v = volumetric flow rate, cm3/sec . V = volume, cm3.)
None of these
224
Pick out the wrong statement
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.
225
The energy of activation of a chemical reaction
is the minimum energy which the molecules must have before the reaction can take place.
226
Chemical kinetics can predict the __________ of a chemical reaction.
rate
227
Which of the following fixes the volume of a batch reactor for a particular conversion and production rate?
Density of mixture
228
Half life period of decomposition of a liquid 'A' by irreversible first order reaction is 12 minutes. The time required for 75% conversion of 'A' is __________ minutes.
24
229
With increase in the space time of an irreversible isothermal reaction being carried out in a P.F. reactor, the conversion will
increase
230
A catalyst promoter
improves the activity of a catalyst.
231
In case of a P.F.R., there
both (a) and (b).
232
For the non-catalytic reaction of particles with surrounding fluid, the time needed to achieve the same fractional conversion for particles of different but unchanging sizes is proportional to the square of particle diameter, when the __________ is the controlling resistance.
diffusion through ash layer
233
If ΔG (free energy change) for a chemical reaction is very large and negative, then the reaction is
very much feasible.
234
In a zero order reaction, reactants concentration does not change with time and the
time for half change is half the time taken for completion of the reaction.
235
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
1.6
236
Design of heterogeous catalytic reactor involves consideration of __________ steps.
both (a) & (b)
237
What is the unit of the rate constant in a chemical reaction in which 10% of the reactant decomposes in one hour, 20% in two hours, 30% in three hours and so on ?
Litre/mole.second
238
For a fluidised bed reactor, the most suitable/relevant model is a __________ model.
bubbling bed
239
The rate at which a chemical substance reacts is proportional to its
active mass
240
In a reaction, the threshold energy is equal to (where, A = activation energy N = normal energy of reactants)
A+N
241
Thermodynamic equilibrium constant in a system is affected by
temperature
242
The most suitable reactor for carrying out an auto-thermal reaction is a
CSTR
243
Which of the following chemical reactions will be favoured by low pressure ?
N2O2 <--> 2NO2
244
A catalyst in a chemical reaction
all (a), (b) and (c).
245
Slurry reactors are characterised by the
both (a) and (b).
246
Limiting reactant in a chemical reaction decides the
conversion
247
Consider the 'n' th order irreversible liquid phase reaction A --> B. Which one of the following plots involving half life of the reaction (t1/2) and the initial reactant concentration (CA0) gives a straight line plot ?
CA0 Vs ln t1/2
248
The rate of forward reaction, at chemical equilibrium is____the rate of backward reaction.
equal to
249
With increase in temperature, the equilibrium __________ rises in case of endothermic reaction.
conversion
250
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
saliva
251
Considering the endotheomic dissociation of CaCO3 in a closed vessel (CaCO3 <-->CaO + CO2), the pressure of CO2 increases, if
the temperature is increased.
252
The exit age distribution of fluid leaving a vessel is used to know the
extent of non-ideal flow in the vessel.
253
From Arhenius law, a plot of loge K versus 1/T gives a straight line with a slope of (-E/R). The unit of E/R is
°K
254
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.
(A) decreases (B) increases
255
The time needed to achieve the same fractional conversion for particles of different sizes (d) when chemical reaction controls, is proportional to
d
256
A balanced chemical reaction equation conforms to the law of
conservation of mass
257
An exothermic reaction takes place in an adiabatic reactor. The product temperature __________ reactor feed temperature.
is always greater than
258
Reverse reaction in a chemical equilibrium is favoured by the
increase in the concentration of oneof the products.
259
Sum of the powers of the concentration terms in the rate equation is called the __________ of the reaction.
overall order
260
During manufacture of H2SO4, the oxidation of SO2 to SO3 by oxygen is an en-dothermic reaction. The yield of SO3 will be maximised, if the
temperature is reduced and pressure is increased.
261
The role of a catalyst in a chemical reaction is to change the
activation energy
262
The vessel dispersion number (D/μL) for plug flow is
263
Molecularity of a reaction
both (b) and (c).
264
BET apparatus is used to determine the
specific surface of a porous catalyst.
265
Carrier in a catalyst increases its
surface area
266
When the reaction is dominated by in-traparticle diffusion, the apparent order of reaction (nD) as measured is related to the true order (n) as
nD = (n+1)/2
267
When the reaction occurs in the diffusion controlled region, the apparent activation energy as measured is only __________ the true value.
half
268
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.
decrease
269
Kinetics of a solid catalysed reaction can best be studied in a __________ reactor.
mixed
270
According to Arhenious equation of temperature dependency of rate constant for an elementary reaction
k ∝ e^-E/RT
271
The reactions of high molecularity are rare, because
of low probability of many body collisions.
272
Which of the following is the most suitable for isothermal operation ?
Back-mix reactor
273
For a first order chemical reaction, the rate constant
has unit of time-1.
274
Which of the following is an autocatalytic reaction ?
Microbial fermentation reaction
275
The performance of a cascade of CSTR's can be improved by adding
more CSTR's in series.
276
A multiple reaction may be classified as a __________ reaction.
all (a), (b) and (c)
277
Holding time for flow reactors is __________ the space time, for constant fluid density
equal to
278
Pick out the wrong statement.
In general, the rate of a reaction becomes triple for every 10°C rise in temperature.
279
The minimum energy required to allow a chemical reaction to proceed is termed as the 'threshold energy '. Chemical reaction with low activation energy are
insensitive to temperature changes.
280
If Thiele modulus is __________ , then the pore diffusion resistance in a catalyst may be considered as negligible.
< 0.5
281
From collison theory, the reaction rate constant is proportional to
T^rn.exp(-E/RT)
282
For a mixed flow reactor operating at steady state, the rate of reaction is given by
FAo/V . XA
283
Catalytic action in a catalytic chemical reaction follows from the ability of catalyst to change the
activation energy
284
In Langmuir treatment of adsorption,
whole surface of the catalyst is essentially uniform and the adsorbed molecule has no effect on the rate of adsorption per site.
285
Organic catalysts differ from the inorganic catalyst in the sense that the former is
proteinous in nature.
286
An endothermic aqueous phase first order irreversible reaction is carried out in an adiabatic plug flow reactor. The rate of reaction
is maximum at the inlet of the reactor.
287
Pick out the wrong statement.
A catalyst increases the potential energy barrier over which the reactants must pass to form products.
288
For an ideal plug flow reactor, the value of Peclet number is
289
An endothermic second order reaction is carried out in an adiabatic plug flow reactor. The rate of heat generation is
maximum at the inlet of the reactor.
290
Equilibrium of a chemical reaction as viewed by kinetics is a __________ state.
dynamic steady
291
The conversion in a mixed reactor/accomplishing a reaction A -->3R is 50% when gaseous reactant 'A' is introduced at the rate of 1 litre/second and the leaving flow rate is 2 litres/second. The holding time for this operation is __________ second.
0.5
292
The size of plug flow reactor (PFR) for all positive reaction orders and for any given duty, is __________ that of mixed reactor.
smaller than
293
A space time of 3 hours for a flow reactor means that
the time required to process one reactor volume of feed (measured at specified conditions) is 3 hours.
294
If the time required for half change is inversely proportional to the square of initial concentration and the velocity depends on the units in which the concentration term is expressed, then the order of reaction is
3
295
The experimentally determined overall order of the reaction, A + B --> C + D, is two. Then the
reaction is elementary with a molecularity of 2.
296
In a continuous flow stirred tank reactor, the composition of the exit stream
is same as that in the reactor.
297
Recycling back of outlet stream to the reactor from an ideal CSTR carrying out a first order liquid phase reaction will result in __________ in conversion.
no change
298
The energy balance equation over a tubular reactor under transient conditions is
a linear partial differential equation.
299
Which of the following factors control the deactivation of a porous catalyst pellet ?
All (a), (b) and (c).
300
For the reaction, A + B -->2B + C,
rA = -rB
301
Transition state theory gives the rate constant as
K α T . e^-E/RT
302
A liquid phase reaction is to be carried out under isothermal conditions. The reaction rate as a function of conversion has been determined experimentally and is shown in the figure given below. What choice of reactor or combination of reactors will require the minimum overall reactor volume, if a conversion of 0.9 is desired ?
PFR followed by a CSTR
303
Pick out the wrong statement.
Activation energy for a reaction is obtained from the intercept of the Ar-rhenious plot.
304
In a reversible reaction, a catalyst increases the rate of forward reaction
and the backward reaction equally.
305
Maximum equilibrium conversion for endothermic reaction is obtained at the __________ temperature.
highest possible
306
When an exothermic reversible reaction is conducted adiabatically, the rate of reaction
continuously decreases.
307
For a first order chemical reaction in a porous catalyst, the Thiele modulus is 10. The effectiveness factor is approximately equal to
0.1
308
The rate equation for the reaction represented by https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/455-245-1.png , is given by - rx = K1 . Cx/(1 + K2 Cx). At high value of Cx (i.e.., K2Cx > > 1), the order of the reaction and the rate constant are respectively
zero order & K1/K2
309
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.
310
Helium-mercury method can be used to determine the __________ of the catalyst particle.
all (a), (b), & (c).
311
For the chemical reaction X --> Y, it is observed that, on doubling the concentration of 'X', the reaction rate quadruples. If the reaction rate is proportional to Cxn, then what is the value of 'n' ?
4
312
Chemical reaction rate of a component depends upon the
all (a), (b) and (c).
313
In a semi-batch reactor
velocity of reaction can be controlled.
314
A trickle bed reactor is the one, which
employs all the three phases (i.e.. .solid, liquid and gas).
315
What is the order of a chemical reaction in which doubling the initial concentration of the reactants doubles the half life time of the reaction ?
316
The excess energy of the reactants required to dissociate into products is known as the __________ energy.
activation
317
In a/an __________ vessel, the fluid enters and leaves following plug flow.
closed
318
Shift conversion reaction
converts CO to CO2 with steam.
319
The importance of diffusion in a catalyst are increased by
all (a), (b) and (c).
320
A back mix reactor is
same as ideal stirred tank reactor.
321
Which one is the rate controlling step in a solid-gas non-catalytic reaction occurring at very high temperature?
Film diffusion
322
The rate of the heterogenous catalytic reaction A(g) + B(g) -->C(g) is given by -rA = k.KA.pA.PB/(1 + KA.PA + Kc.pc), where KA and Kc are the adsorption equilibrium constants. The rate controlling step for this reaction is
surface reaction between absorbed A and B in the gas phase.
323
For a __________ order chemical reaction, https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/449-168-1.png , the half life period is independent of the initial concentration of the reactant A.
first
324
The ratio of moles of a reactant converted into the desired product to that converted into unwanted product is called
selectivity
325
The response curve for a step input signal from a reactor is called C-curve. The variance of C-curve in a 'tanks in series model' comprising of 'm' tanks is equal to
1/m
326
The eddy diffusivity for a liquid in plug flow must be
327
For multiple reactions, the flow pattern within the vessel affects the
both (a) and (b)
328
For the same residence time, which one will give the maximum conversion ?
Single tubular flow reactor (v = 5 litres).
329
__________ gas is normally employed in B.E.T.method of finding out the surface area of catalyst.
N2
330
The exit age distribution curve E(t) for an ideal CSTR with the average residence time, τ, is given by
[(e^-t/τ)/T]
331
The rate constant of a reaction depends on the
temperature of the system.
332
For the reversible reaction A <-->2B, if the equilibrium constant K is 0.05 mole/litre; starting from initially 2 moles of A and zero moles of B, how many moles will be formed at equilibrium ?
0.338
333
For identical flow rate and feed composition, X plug flow reactors (PER) in series with a total volume V gives the same conversion as single
PFR of volume V
334
Time required for 50% decomposition of a liquid in an isothermal batch reactor following first order kinetics is 2 minutes. The time required for 75% decomposition will be about __________ minutes.
4
335
For a __________ order reaction, the units of rate constant and rate of reaction are the same.
zero
336
In case of staged packed bed reactors carrying out exothermic reaction, use
all (a), (b) and (c).
337
Vegetable oils are hydrogenated in a __________ reactor.
slurry
338
Pure A in gas phase enters a reactor 50% of this A is converted to B through the reaction, A --> 3B. Mole fraction of A in the exit stream is
45660
339
The rate of reaction does not decrease appreciably as the reaction proceeds in case of __________ reactions.
autocatalytic
340
For all positive reaction orders for a particular duty,
mixed reactor is always larger than the plug-flow reactor.
341
The heat of reaction
is independent of the mechanism of reaction.
342
Which of the following does not produce a change in the value of rate constant of a reaction ?
Concentration and catalyst
343
With increase in temperature, the equilibrium conversion of a reversible exothermic reaction
decreases
344
In a CSTR __________ varies with time.
neither (a) nor (b)
345
The following gas phase reactions are carried out isothermally in a CSTR.
A --> 2R ; r1 = k1pA ;
k1 = 20mole/(sec.m3 bar)
A --> 3S ; r2 = k2 pA ;
k2 = 40mole/(sec.m3 .bar)
What is the maximum possible value of FR(mole/sec.) ?
45691
346
As the chemical reaction proceeds, the rate of reaction
decreases.
347
Pick out the wrong statement.
A catalyst initiates a reaction.
348
In a first order reaction, the time required to reduce the concentration of reactant from 1 mole/litre to 0.5 mole/litre will be __________ that required to reduce it from 10 moles/litre to 5 moles/litre in the same volume.
same as
349
Photo-chemical reactions occur in presence of
sunlight.
350
n' number of plug flow reactors (P.F.R) in series with a total volume 'V' gives the same conversion as one P.F.R. of volume
V
351
Knudsen diffusion is directly proportional to
sqrt(T)
352
Fractional conversion __________ for an exothermic reversible chemical reaction, when the temperature is maximum.
decreases
353
Non-catalytic fluid-solid reactions are represented by __________ model.
both (a) and (b)
354
A pulse tracer is introduced in an ideal CSTR (with a mean residence time ι) at time, t = 0. The time taken for the exit concentration of the tracer to reach half of its initial value will be
2τ
355
On application of pressure to the equilibrium system, ice <--> water ; which of the following phenomenon will occur ?
More water will be formed.
356
Participation of __________ is involved in the occurrence of a chemical reaction.
electrons
357
Promoter.
increases the number of active centres by increasing the unevenness of catalyst surface and by creating discontinuities in the crystals.
358
The rate constant of a reaction is a function of the
temperature of the system.
359
Mean residence time is equal to the space time, when
all (a), (b) and (c).
360
If 'n' is the order of reaction, then unit of rate constant is
1/(time)(concentration)^n - 1
361
Batch process is preferred over continuous process, when the
all (a), (b) & (c)
362
The value of 'n' for a chemical reaction A --> B, whose reaction rate is -->CAn, will be __________ if the rate of the reaction increases by a factor of 8, when the concentration of is doubled.
3
363
With the same reaction time, initial concentration and feed rate, the reaction 2A -->B is carried out separately in CSTR and P.F. reactor of equal volumes. The conversion will be
higher in P.F. reactor
364
For any reaction, we may write conversion as a function of
all (a), (b) & (c)
365
The use of space time is preferred over the mean residence time in the design of a/an
ideal tubular-flow reactor
366
Autocatalytic reactions are best carried out in a
recycle reactor
367
The gas phase reaction 2A <--> B is carried out in an isothermal plug flow reactor. The feed consists of 80 mole % A and 20 mole % inerts. If the conversion of A at the reactor exit is 50%, then CA/CA0 at the outlet of the reactor is
45785
368
A batch reactor suffers from following disadvantage.
All (a), (b)and(c).
369
A first order reaction is to be treated in a series of two mixed reactors. The total volume of the two reactors is minimum, when the reactors are
equal in size.
370
Half life period of a chemical reaction is proportional to CA0-1 , if the reaction is of __________ order.
second
371
The irreversible reaction, X --> Y, is the special case of the reversible reaction, X <-->Y, in which the
all (a), (b) and (c).
372
The equilibrium constant K of a chemical reaction depends on
temperature only.
373
The reaction rate almost gets doubled for 10°C rise in temperature. This is due to the fact that the
fraction of molecules having threshold energy increases.
374
Which of the following is not a unit of reaction rate ?
None of these
375
Brunaur, Emmet and Teller (BET) equation is used to determine the specific surface area of a porous particle but not the pore volume & the porosity of the catalyst bed. Which of the following postulates is not used to derive BET equation ?
There is no dynamic equilibrium between successive layer.
376
The sequence in which three CSTR's of volumes 5, 10 and 15 m3 will be connected in series to obtain the maximum production in a second order irreversible reaction is
15, 10, 5
377
The unit of frequency factor in Arhenious equation is
same as that of rate constant.
378
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)
increases
379
Reaction of benzene with chlorine gas to produce tri-chlorobenzene exemplifies a/an __________ reaction.
consecutive
380
For the gaseous reaction 2A --> B, where the feed consists of 50 mole % A and 50 mole % inerts, the expansion factor is
-0.25
381
The molecularity and the order of reaction respectively, for the hydrolysis of methyl acetate in presence of acids are
2 & 1
382
The irreversible reaction is a special case of reversible reaction, if the
reactant concentration at equilibrium condition is zero.
383
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
7
384
For the liquid phase parallel reactions:
R, rR = K1.CA2; E1 = 80 KJ/mole
S, rs= K1.CA ; E2 = 120 KJ/mole
The desired product is R. A higher selectivity of R will be achieved, if the reaction is conducted at
high temperature in a PFR.
385
In an ideal mixed reactor (at steady state), the
all (a), (b) and (c).
386
The knowledge of initial concentration and rate constant is necessary to determine the half life time of a reaction of __________ order.
second
387
Which of the following factors control the design of a fluid-solid reactor ?
All (a), (b) and (c).
388
A Catalyst
shortens the time to reach the equilibrium.
389
The synthesis of proteins and metabolism in biological objects occur in the presence of biocatalyst called
fungi
390
Pick out the wrong statement.
The intercept of the Arrhenious plot is called the 'activation energy'.
391
Kinetics of a catalytic reaction can be best studied on a/an __________ reactor.
either (a), (b) and (c).
392
In case of a __________ reactor, the composition in the reactor and at the exit of the reactor is the same.
back-mix
393
Exothermic reactions are best carried out in
CSTR followed by a plug flow reactor.
394
Reactions with high activation energy are
very temperature sensitive
395
If n = overall order of a chemical reaction. a = initial concentration of reactant. t = time required to complete a definite fraction of the reaction. Then pick out the correct relationship.
t ∝ 1/a^n-1
396
In case of a/an __________ chemical reaction, conversion increases with the rise in temperature.
reversible endothermic
397
A space velocity of 5 hr-1 means that
five reactor volumes of feed (at specified conditions) are being fed into the reactor per hour.
398
With increase in initial concentration, the fractional conversion of a first order reaction in a given time
remains constant
399
The rate of reaction of a/an __________ reaction is not affected by temperature rise.
photochemical
400
With an increase in pressure in gaseous phase chemical reactions, the fractional conversion __________ when the number of moles decreases.
increases
401
Half-life period for a first order reaction is __________ the initial concentration of the reactant.
independent of
402
Carbon particles accummulated on the catalyst used in the gas oil cracking lies in the category of __________ poison.
deposited
403
What is the dispersion number for a plug flow reactor ?
404
The decomposition of A into B is represented by the exothermic reaction, A <--> 2B. To achieve maximum decomposition, it is desirable to carry out the reaction.
at low P and low T.
405
The catalytic converter for conversion of SO2 to SO3 by contact process should have a feed with SO2 content between
7-10%
406
If the pore diffusion controls in a catalytic reaction, the apparent activation energy Ea is equal to
ED/2
407
Collision theory gives the rate constant for bimolecular reaction as
K α e^-E/RT
408
Find a mechanism that is consistent with the rate equation and reaction given below:
2A + B --> A2B, ( - rA) = k.CA.CB
A + A <--> AA;AA + B --> A2B
409
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.
3
410
The temperature dependence of reaction rate constant (K) by Arhenius law is given by
K α e^-E/RT
411
Velocity of a chemical reaction
none of these.
412
Backmixing is most predominant in
a single CSTR.
413
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)
decreases
414
Fluidised bed reactor is characterised by
uniformity of temperature.
415
In which of the following gaseous phase reversible reactions, the product yield can not be increased by the application of high pressure ?
N2 + O2 <--> 2NO
416
Space time equals the mean residence time
when the density of the reaction mixture is constant.
417
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.
16
418
Rate constant 'k' and absolute temperature 'T' are related by collision theory (for bimolecular) as
k ∝ sqrt(T)
419
The conversion for a first order liquid phase reaction. A --> B in 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
75
420
What is the dispersion number for a CSTR?
∞
421
Rate of a chemical reaction is independent of the concentration of the reactants for a __________ reaction.
zero order
422
With increase in temperature, the rate constant obeying Arhenious equation
increases.
423
Bulk diffusion in catalyst pore __________ with increase in pressure.
decreases
424
Pick out the correct statement.
The rate constant for a first order reaction does not change on changing the concentration units.
425
The concentration of A in a first order reaction, A --> B, decreases
exponentially with time.
426
The equilibrium constant of chemical reaction __________ in the presence of catalyst.
remains unaffected
427
The order of a chemical reaction is
an experimentally determined quantity.
428
A chemical reaction occurs, when the energy of the reacting molecules is __________ the activation energy of reaction.
equal to or more than
429
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
0.144
430
Catalyst is a substance, which __________ chemical reaction.
can either increase or decrease the speed of a
431
The residence time distribution of an ideal CSTR is
exp (-t/τ)
432
A rise in temperature
all (a), (b) and (c).
433
The enzyme which can catalyse the conversion of glucose to ethyl alcohol is
zymase
434
For reaction, P + 2 -->3R, molar rate of consumption of P is
half of that of Q.
435
If pore diffusion is the controlling step in a solid catalysed reaction, the catalyst
porosity is of less importance.
436
The conversion of a reactant, undergoing a first order reaction, at a time equal to three times the half life of the reaction is
0.875
437
In case of unimolecular type elementary reaction, https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/449-176-1.png , plug flow reactor as compared to mixed reactor is
more
438
What is the value of 'n' if the reaction rate of the chemical reaction A --> B, is proportional to CAn and it is found that the reaction rate triples, when the concentration of 'A' is increased 9 times ?
45659
439
The first order series reaction https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/473-457-1.png is conducted in a batch reactor. The initial concentrations of A, B and C (CA0, CB0, CC0 respectively) are all non-zero. The variation of CB with reaction time will not show a maximum, if
k2 CB0 > k1 CA0
440
A second order reaction of the form A + B --> C is called a pseudo-first order reaction, when
CB0 ≥ CB0
441
Pick out the wrong statement.
According to the penetration theory, the mass transfer co-efficient decreases, if the exposure time of an eddy to the solute decreases.
442
Effectiveness factor (E) of a catalyst pellet is defined as https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/458-294-1.png , Effectiveness factor for a first order reaction is given by (where, T = Thiele modulus)
tan hT/T
443
Inversion of cane sugar is an example of
bimolecular reaction with first order.
444
Pick out the correct statement.
Pressure changes do not change the equilibrium concentrations.
445
In which of the following gaseous phase reactions, the equilibrium of the reaction remains unaffacted by pressure changes ?
N2 + O2 <--> 2NO
446
Integral method for analysing the kinetic data is used
both (a) and (b).
447
The rate of a gas phase reaction is given by K . 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.
16
448
Rate of a chemical reaction is not affected by the
number of molecules of reactants taking part in the reaction.
449
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.
proportional to
450
__________ resistance is not involved in the combustion of a carbon particle.
Ash
451
In an ideal P.F.R. at steady state conditions
the conversion of the reactant varies from point to point along a flow path.
452
B.E.T. method of finding out surface area of a catalyst, uses the extension of __________ isotherm.
Langmuir
453
In a chemical reaction, repesented by, https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/454-241-1.png , it is observed that the
(i) rate of reaction increases by a factor of 4 on doubling the concentration of the reactant.
(ii) rate of reaction increases by a factor of 9 on trebling the concentration of the reactant.
Then the rate of the reaction is proportional to(where, CA = contentration of the reactant)
CA^2
454
Which of the following holds good for an elementary reaction,https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/455-249-1.png ?
Three times the rate of disappearance of 'X' is equal to the rate of appearance of 'Z'.
455
An example of autothermal reactor operation is
ethylene oxidation
456
For a packed bed reactor; the presence of a long tail in the residence time distribution curve is an indication of
dead zone
457
Space time in flow reactor is
both (a) and (b).
458
For a first order isothermal chemical reaction in a porous catalyst, the effectiveness factor is 0.3. The effectiveness factor will increase if the
catalyst size is reduced or the catalyst diffusivity is increased.
459
Cold shot cooling is only practical when the feed temperature is __________ than the reaction temperature.
much lower
460
The preferred reacting system for oxidation of o-xylene to phthalic anhydride is
jacketted liquid phase CSTR.
461
The effectiveness factor for large value of Thiele modulus (L.sqrt(K/D1)) of a solid catalysed first order reaction is equal to (where, L = length of the reactor, cm, D1 = diffusion co-efficient, cm2/second)
1/L(sqrt(K/D1))
462
A first order reaction A B occurs in an isothermal porous catalyst pellet of spherical shape. If the concentration of A at the centre of the pellet is much less than at the external surface, the process is limited by
diffusion within the pellet.
463
Following isothermal kinetic data are obtained in a basket type of mixed flow reactor for a porous catalyst. Determine the role of pore diffusion and external mass transfer processes. https://www.indiabix.com/_files/images/chemical-engineering/chemical-reaction-engineering/477-486-1.png
Strong pore diffusion control and mass transfer not controlling.
