Chemical Reaction Engineering Flashcards
1
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
2
Q
A catalyst
A
lowers the activation energy of reacting molecules.
3
Q
What is the order of a chemical reaction, A + 2B -> , 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
7/2
4
Q
A first order reaction requires two equal sized CSTR. The conversion is
A
more when they are connected in series.
5
Q
A reactor is generally termed as an autoclave, when it is a
A
high pressure batch reactor.
6
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.
7
Q
The rate constant of a chemical reaction decreases by decreasing the
A
temperature
8
Q
Reaction rate equation for the reaction, . If S at is present in large excess, what is the order of this reaction?
A
1
9
Q
Rate of a gaseous phase reaction is given by, . The unit of rate constant is
A
(atm)-1.(hr)-1
10
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
11
Q
Which of the following is the most suitable for very high pressure gas phase reaction ?
A
Tubular flow reactor
12
Q
In an exothermic chemical reaction, the reactants compared to the products have
A
more energy
13
Q
A batch reactor is suitable for
A
liquid phase reactions.
14
Q
In a consecutive reaction system when E1 is much greater than E2, the yield of B increases with the
A
increase of temperature.
15
Q
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
A
is at the highest allowable temperature throughout.
16
Q
For a heterogeneous catalytic reaction
A
free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction.
17
Q
The increase in the rate of reaction with temperature is due to
A
decrease in activation energy.
18
Q
‘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.
A
any
19
Q
For the irreversible elementary reactions in parallel viz , the rate of disappearance of ‘X’ is equal to
A
CA(K1+K2)
20
Q
BET apparatus
A
none of these.
21
Q
For an isothermal variable volume batch reactor, the following relation is applicable for a first order irreversible reaction.
A
22
Q
For a solid catalysed chemical reaction, the effectiveness of solid catalyst depends upon the __________ adsorption.
A
chemical
23
Q
Pick out the correct statement.
A
A catalyst lowers the activation energy of the reacting molecules.
24
Q
The dimensions of rate constant for reaction 3A B are (l/gm mole)/min. Therefore the reaction order is
A
2
25
Pick out the correct statement
Reactions with high activation energies are very temperature sensitive.
26
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
27
Sulphuric acid is used as a catalyst in the
alkylation of hydrocarbons.
28
Pick out the wrong statement.
Mixed reactor is always smaller than the plug flow reactor for all positive reaction orders for a particular duty.
29
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
30
__________ is the controlling step in a highly temperature sensitive fluid-solid non-catalytic reaction.
Chemical reaction
31
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
32
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
33
__________ is the controlling step in a highly temperature sensitive fluid-solid non-catalytic reaction.
Chemical reaction
34
An autothermal reactor is
completely self-supporting in its thermal energy requirements.
35
The rate constant of a first order reaction depends on the
temperature.
36
A reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.
autocatalytic
37
Conversion increases with increase in temperature in case of a an __________ reaction.
reversible endothermic
38
A photochemical reaction is __________ light.
initiated by
39
'Unreacted core model' represents the reaction involving
roasting of sulphide ores.
40
If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is the __________ diffusion.
film
41
The units of frequency factor in Arhenious equation
are the same as those of the rate constant.
42
Which of the following is not a chemical step in a fluid solid catalytic reaction ?
None of these
43
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
44
In case of __________ reactions, the reaction rate does not decrease appreciably as the reaction proceeds.
auto catalytic
45
Which of the following is an independent variable for a batch tank reactor with uniform concentration and temperature ?
Time
46
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
47
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
48
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.
49
Pick out the correct statement.
A lower temperature favours the reaction of lower activation energy.
50
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)
51
A batch reactor is characterised by
variation in extent of reaction and properties of the reaction mixture with time.
52
Rate determining step in a reaction consisting of a number of steps in series is the __________ step.
slowest
53
A catalyst in a chemical reaction __________ free energy change in the reaction.
either (a) or (b); depends on the type of catalyst
54
When all the limiting reactant is consumed in the reaction, the operational yield __________ the relative yield.
equals
55
The catalyst in a second order reversible reaction increases the rate of the forward reaction
and backward reaction equally.
56
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.
0.60
57
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
58
A reaction which is catalysed by a base is catalysed by all substances which have a tendency to
gain a proton
59
For a homogeneous reaction of nth order, the dimension of the rate constant is given by
(concentration)1 - n/(time)
60
The fractional volume change between no conversion and complete conversion, for the isothermal gas phase reaction, 2A -> R, is
-0.5
61
The reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.
autocatalytic
62
A typical example of an exothermic reversible reaction conducted at high pressure in industry is
dehydration of ethanol.
63
Study of chemical kinetics is the easiest in the case of __________ reactions.
irreversible
64
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
∞
65
Pick out the wrong statement.
The order and molecularity of a complex reaction may not be the same.
66
The rate at which a chemical substance reacts is proportional to its
active mass
67
Which of the following curves shows the effect of temperature on the extent of gas-solid adsorption at a given pressure ?
Adsorption isobar
68
For an ideal mixed flow reactor (CSTR), the exit age distribution E(t) is given by
none of the above
69
Fluid flow in a real packed bed can be approximated as __________ model.
dispersion
70
The 'E' curve for a non-ideal reactor defines the fraction of fluid having age between t and t + dt
at the outlet
71
A reaction which is catalysed by an acid is also catalysed by any substance, which has a tendency to
lose a proton.
72
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, high CB
73
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
74
In chamber process of sulphuric acid manufacture in industry, the gas phase oxidation of SO2 to SO3 is accomplished by a __________ reaction.
catalytic homogenous
75
If the rate of a chemical reaction becomes slower at a given temperature, then the
free energy of activation is higher.
76
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
77
The value of steric factor 'P' in the equation k = PZeE/RT usually ranges from
l.0 to 10-8
78
For a zero order reaction, the concentration of product increases with the
increase of reaction time.
79
Pick out the wrong statement.
A batch reactor can not be used to study the kinetics of catalytic reaction.
80
Effectiveness factor of a catalyst pellet is a measure of the __________ resistance.
pore diffusion
81
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
82
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
83
__________ catalytic reaction is involved in the thermal cracking of gas oil.
Homogeneous
84
Variables affecting the rate of homogeneous reactions are
pressure, temperature and composition.
85
A chemical reaction occurs when the energy of the reacting molecules is __________ the activation energy of the reaction.
equal to or more than
86
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.
87
A catalyst is said to be a negative catalyst, ifit
retards the rate of reaction.
88
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
89
.
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
90
Pick out the wrong statement.
When the reaction rate is independent of temperature, the reaction is said to be of zero order.
91
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.
92
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
93
In a semi-batch reactor,
velocity of reaction can be controlled.
94
In a chemical reaction , 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
95
In the gaseous phase ammonia formation reaction (N2 + 3H2 2NH3), the value of the equilibrium constant depends on the
temperature.
96
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
97
For an ideal gas mixture undergoing a reversible gaseous phase chemical reaction, the equilibrium constant
increases with pressure.
98
A batch reactor is
suitable for liquid phase reactions involving small production rate.
99
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
100
A chemical reaction is of zero order, when the reaction rate is (where, CA = concentration of reactant)
none of these.
101
Second order consecutive irreversible reactions 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)?
1/4
102
There is no correspondence between stoichiometry and the rate equation in case of a/an __________ reaction.
non-elementary
103
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.
104
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
105
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
1.60
106
For a fluidised bed reactor, the most suitable/relevant model is a __________ model.
bubbling bed
107
Thermodynamic equilibrium constant in a system is affected by
temperature
108
The most suitable reactor for carrying out an auto-thermal reaction is a
CSTR
109
Limiting reactant in a chemical reaction decides the
conversion
110
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
111
Pick the WRONG design guideline for a reactor in which the reactions, A -> R (desired) and A -> S (undesired) are to take place. The ratio of the reaction rates is .
avoid recycle, when a > b.
112
With increase in temperature, the equilibrium __________ rises in case of endothermic reaction.
conversion
113
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
114
The exit age distribution of fluid leaving a vessel is used to know the
extent of non-ideal flow in the vessel.
115
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
116
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
117
An exothermic reaction takes place in an adiabatic reactor. The product temperature __________ reactor feed temperature.
is always greater than
118
The equilibrium constant for the reversible reaction, , is affected by the
pressure of the system.
119
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.
120
The vessel dispersion number (D/μL) for plug flow is
0
121
When the reaction occurs in the diffusion controlled region, the apparent activation energy as measured is only __________ the true value.
half
122
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
123
An elementary liquid phase decomposition reaction is to be carried out in a CSTR. The design equation is
kτ = XA/(1 - XA)
124
Kinetics of a solid catalysed reaction can best be studied in a __________ reactor.
mixed
125
The reactions of high molecularity are rare, because
of low probability of many body collisions.
126
Which of the following is the most suitable for isothermal operation ?
Back-mix reactor
127
For a first order chemical reaction, the rate constant
has unit of time-1.
128
The performance of a cascade of CSTR's can be improved by adding
more CSTR's in series.
129
The order of the reaction, , is
0
130
Arhenious equation shows the variation of __________ with temperature.
rate constant
131
When a catalyst increases the rate of chemical reaction, the rate constant
increases
132
In which of the following reactions, the equilibrium will shift to the right, if the total pressure is increased?
N2 + O2 <-> 2NO
133
Oil is hydrogenated using nickel catalyst in a __________ reactor.
slurry
134
The half life period 't' of a zero order reaction, , is equal to
CA0/2K
135
The performance equations for constant density systems are identical for
P.F.R. and batch reactor.
136
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.
137
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
138
In the fluid catalytic cracker (FCC), the cracking reaction is __________ (A) and the regeneration is___(B) __________
(A) endothermic (B) exothermic
139
Pick out the correct statement.
A catalyst does not change AH of the reaction.
140
Promoter is added to the catalyst to improve its
sensitivity
141
When a high liquid hold up is required in a reactor for gas liquid reaction, use __________ coloumn.
bubble
142
For a tubular flow reactor with uniform concentration and temperature, the independent variable is
length
143
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.
144
The first order gas phase reaction is conducted isothermally in batch mode. The rate of change of conversion with time is given by
145
Higher free energy of activation of a chemical reaction (at a given temperature) implies
slower rate of reaction.
146
Calcination reaction of limestone (CaCO3 -> CaO + CO2) goes to completion in the rotary kiln, because
CO2 escapes continuously.
147
For the reaction , the rate of formation of Z is 0.2 gm mole/litre.hr. what is the rate of disappearance of X in gm mole/litre. hr ?
0.4
148
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
149
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.
150
Pick out the wrong statement.
Hydrolysis of ester in presence of alkali or acid is a zero order reaction.
151
Chemical kinetics can predict the __________ of a chemical reaction.
rate
152
Which of the following fixes the volume of a batch reactor for a particular conversion and production rate ?
Density of mixture
153
Volume change for unimolecular type first order reaction , increases __________ with time.
exponentially
154
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
155
.
Decomposition rate of a liquid 'X' which decomposes as per the reaction is given by
(K1 + K2)CX
156
With increase in the space time of an irreversible isothermal reaction being carried out in a P.F. reactor, the conversion will
increase
157
A catalyst promoter
improves the activity of a catalyst.
158
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
159
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.
160
If Thiele modulus is __________ , then the pore diffusion resistance in a catalyst may be considered as negligible.
< 0.5
161
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.
162
Organic catalysts differ from the inorganic catalyst in the sense that the former is
proteinous in nature.
163
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.
164
The size of plug flow reactor (PFR) for all positive reaction orders and for any given duty, is __________ that of mixed reactor.
smaller than
165
The experimentally determined overall order of the reaction, A + B C + D, is two. Then the
reaction is elementary with a molecularity of 2.
166
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
167
Pick out the wrong statement.
Activation energy for a reaction is obtained from the intercept of the Ar-rhenious plot.
168
In a reversible reaction, a catalyst increases the rate of forward reaction
and the backward reaction equally.
169
When an exothermic reversible reaction is conducted adiabatically, the rate of reaction
passes through a maximum.
170
For a first order chemical reaction in a porous catalyst, the Thiele modulus is 10. The effectiveness factor is approximately equal to
0.1
171
The rate equation for the reaction represented by, 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
172
In solid catalysed reactions the diffusional effects are more likely to affect the overall rate of reaction for
slow reactions in catalyst of small pore diameter.
173
In a semi-batch reactor
velocity of reaction can be controlled.
174
A trickle bed reactor is the one, which
employs all the three phases (i.e.. .solid, liquid and gas).
175
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 ?
0
176
In a/an __________ vessel, the fluid enters and leaves following plug flow.
closed
177
Shift conversion reaction
converts CO to CO2 with steam.
178
For a __________ order chemical reaction, , the half life period is independent of the initial concentration of the reactant A.
1
179
The eddy diffusivity for a liquid in plug flow must be
0
180
For the same residence time, which one will give the maximum conversion ?
Single tubular flow reactor (v = 5 litres).
181
The rate constant of a reaction depends on the
temperature of the system.
182
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
183
The heat of reaction
is independent of the mechanism of reaction.
184
Which of the following does not produce a change in the value of rate constant of a reaction ?
Concentration and catalyst
185
With increase in temperature, the equilibrium conversion of a reversible exothermic reaction
decreases
186
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.) ?
2/3
187
Pick out the wrong statement.
A catalyst initiates a reaction.
188
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
189
'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
190
Fractional conversion __________ for an exothermic reversible chemical reaction, when the temperature is maximum.
decreases
191
Participation of __________ is involved in the occurrence of a chemical reaction.
electrons
192
If 'n' is the order of reaction, then unit of rate constant is
1/(time)(concentration)n - 1
193
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
194
Autocatalytic reactions are best carried out in a
recycle reactor
195
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
5/8
196
A second order liquid phase reaction, A B, is carried out in a mixed flow reactor operated in semi batch mode (no exit stream). The reactant A at concentration CAF is fed to the reactor at a volumetric flow rate of F. The volume of the reacting mixture is V and the density of the liquid mixture is constant. The mass balance for A is
197
Half life period of a chemical reaction is proportional to CA0-1 , if the reaction is of __________ order.
second
198
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.
199
Which of the following is not a unit of reaction rate ?
None of these
200
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.
201
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
202
The unit of frequency factor in Arhenious equation is
same as that of rate constant.
203
Reaction of benzene with chlorine gas to produce tri-chlorobenzene exemplifies a/an __________ reaction.
consecutive
204
For the gaseous reaction 2A -> B, where the feed consists of 50 mole % A and 50 mole % inerts, the expansion factor is
-0.25
205
The molecularity and the order of reaction respectively, for the hydrolysis of methyl acetate in presence of acids are
2 & 1
206
The irreversible reaction is a special case of reversible reaction, if the
reactant concentration at equilibrium condition is zero.
207
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
208
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.
209
The knowledge of initial concentration and rate constant is necessary to determine the half life time of a reaction of __________ order.
second
210
The synthesis of proteins and metabolism in biological objects occur in the presence of biocatalyst called
fungi
211
In case of a __________ reactor, the composition in the reactor and at the exit of the reactor is the same.
back-mix
212
Exothermic reactions are best carried out in
CSTR followed by a plug flow reactor.
213
In case of a/an __________ chemical reaction, conversion increases with the rise in temperature.
reversible endothermic
214
Carbon particles accummulated on the catalyst used in the gas oil cracking lies in the category of __________ poison.
deposited
215
What is the dispersion number for a plug flow reactor ?
0
216
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.
217
If the pore diffusion controls in a catalytic reaction, the apparent activation energy Ea is equal to
ED/2
218
Collision theory gives the rate constant for bimolecular reaction as
K α e-E/RT
219
For a __________ order chemical reaction, , the fractional conversion of reactant 'A' is proportional to time.
zero
220
Velocity of a chemical reaction
none of these.
221
Backmixing is most predominant in
a single CSTR.
222
Fluidised bed reactor is characterised by
uniformity of temperature.
223
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
224
What is the dispersion number for a CSTR?
∞
225
Rate of a chemical reaction is independent of the concentration of the reactants for a __________ reaction.
zero order
226
The concentration of A in a first order reaction, A -> B, decreases
exponentially with time.
227
The equilibrium constant of chemical reaction __________ in the presence of catalyst.
remains unaffected
228
The order of a chemical reaction is
an experimentally determined quantity.
229
Catalyst is a substance, which __________ chemical reaction.
can either increase or decrease the speed of a
230
The residence time distribution of an ideal CSTR is
exp(-t/τ)
231
The enzyme which can catalyse the conversion of glucose to ethyl alcohol is
zymase
232
If pore diffusion is the controlling step in a solid catalysed reaction, the catalyst
porosity is of less importance.
233
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
234
In case of unimolecular type elementary reaction, , plug flow reactor as compared to mixed reactor is
more
235
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 ?
1/2
236
The first order series reaction 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
237
A second order reaction of the form A + B C is called a pseudo-first order reaction, when
CB0 ≥ CB0
238
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.
239
Effectiveness factor (E) of a catalyst pellet is defined as, Effectiveness factor for a first order reaction is given by (where, T = Thiele modulus)
tan hT/T
240
Pick out the correct statement.
Pressure changes do not change the equilibrium concentrations.
241
Rate of a chemical reaction is not affected by the
number of molecules of reactants taking part in the reaction.
242
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
243
An example of autothermal reactor operation is
ethylene oxidation
244
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.
245
Cold shot cooling is only practical when the feed temperature is __________ than the reaction temperature.
much lower
246
The preferred reacting system for oxidation of o-xylene to phthalic anhydride is
jacketted liquid phase CSTR.
