A space velocity of 5 hr means that

after every 5 hours, reactor is being filled with the feed.

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

after every 5 hours, reactor is being filled with the feed.

cent per cent conversion can be achieved in at least 5 hours.

a fixed conversion of a given batch of feed takes 5 hours.

The concentration of A in a first order reaction, , decreases

very abruptly towards the end of the reaction.

Which of the following fixes the volume of a batch reactor for a particular conversion and production rate?

perating conditions (e.g. pressure and temperature)

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 isA. absorption of A.

urface reaction between A in the gas phase and absorbed B

urface reaction between absorbed A and absorbed B

urface reaction between absorbed A and B in the gas phase

urface reaction between A in the gas phase and absorbed B

Which of the following is the optimum operating condition for an exothermic reversible reaction taking place in a plug-flow reactor?

ery low temperature should be used throughout the reaction

emperature should be high in the beginning and decreased towards the end of the reaction

ery low temperature should be used throughout the reaction

ery high temperature should be used throughout the reaction

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.)

eactor dispersion number (D/vL)

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.

oth the conversion as well as concentrations will be different

oth conversion as well as concentration are same

onversion in both will be the same but concentrations will be different

oth the conversion as well as concentrations will be different

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 rR/rS = (k₁/k₂).Csub>Aa-b

se batch reactor or plug flow reactor, when a > b

se high pressure and eliminate inerts, when a > b

se batch reactor or plug flow reactor, when a > b

se CSTR with a high conversion, when a > b

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

urface Kc/(1 + TS) reaction between absorbed A and B in the gas phase

urface reaction between absorbed A and absorbed B

urface reaction between A in the gas phase and absorbed B

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?

he adsorbed layer may be polymolecular in thickness and the heat of adsorption in each layer (except the first one) is involved in each of the evaporation process

here is no dynamic equilibrium between successive layer

he adsorbed layer may be polymolecular in thickness and the heat of adsorption in each layer (except the first one) is involved in each of the evaporation process

1443 + Mcqs in Chemical Reaction Engineering in Chemical Engineering Page 3 McqOptions

101.	Vegetable oils are hydrogenated in a __________ reactor.
A.	slurry
B.	plug flow
C.	homogeneous catalytic
D.	none of these
Answer» B. plug flow

102.	The sequence in which three CSTR's of volumes 5, 10 and 15 m will be connected in series to obtain the maximum production in a second order irreversible reaction is
A.	15, 10, 5
B.	5, 10, 15
C.	10, 5, 15
D.	10, 15, 5
Answer» B. 5, 10, 15

103.	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:CHOH CH + HO2CHOH CH - O - CH + HOThe percent conversion of ethanol in the reactor is
A.	100
B.	97.5
C.	95
D.	2.5
Answer» B. 97.5

104.	For the reversible reaction 2, 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 ?
A.	0.253
B.	0.338
C.	0.152
D.	0.637
Answer» C. 0.152

105.	If is the quantity of reactants initially present, the quantity left after '' half periods will be equal to
A.	(
B.	)
Answer» C.

106.	For a __________ order chemical reaction, , the fractional conversion of reactant '' is proportional to time.
A.	zero
B.	first
C.	second
D.	third
Answer» B. first

107.	The order of the chemical reaction, , whose rate equation is given as -= . is
A.	0
B.	1
C.	2
D.	3
Answer» E.

108.	The decomposition of into is represented by the exothermic reaction, 2. To achieve maximum decomposition, it is desirable to carry out the reaction.
A.	at high P and high T.
B.	at low P and high T.
C.	at low P and low T.
D.	at high P and low T.
Answer» D. at high P and low T.

109.	For the gaseous reaction 2 , where the feed consists of 50 mole % and 50 mole % inerts, the expansion factor is
A.	1
B.	-0.5
C.	-0.25
D.	0
Answer» D. 0

110.	A pollutant degrades according to first order kinetics. An aqueous stream containing at 2 kmole/m and volumetric flow rate 1m /h requires a mixed flow reactor of volume V to bring down the pollutant level to 0.5 kmole/m . 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/m , the volume of the mixed flow reactor should be increased by a factor of
A.	7
B.	6
C.	3
D.	7/3
Answer» B. 6

111.	For the liquid phase parallel reactions:, = .; = 80 KJ/mole, = 1. ; = 120 KJ/mole The desired product is R. A higher selectivity of R will be achieved, if the reaction is conducted at
A.	low temperature in a CSTR.
B.	high temperature in a CSTR.
C.	low temperature in a PFR.
D.	high temperature in a PFR.
Answer» E.

113.	If = overall order of a chemical reaction. = initial concentration of reactant. = time required to complete a definite fraction of the reaction. Then pick out the correct relationship.
A.	∝
Answer» C.

115.	The catalytic converter for conversion of SO to SO by contact process should have a feed with SO content between
A.	2-5%
B.	7-10%
C.	12-15%
D.	20-25%
Answer» C. 12-15%

116.	If helium is introduced in a reactor containing O, SO and SO at equilibrium, so that total pressure increases while volume and temperature remains constant. In this case the dissociation of SO (as per Le Chatlier principle)
A.	decreases
B.	increases
C.	remains unaltered
D.	changes unpredictably.
Answer» B. increases

117.	With increase in / in case of a unimolecular type elementary reactions, the fractional yield of '' in mixed reactor (for a given conversion of '')
A.	decreases
B.	increases
C.	increases linearly
D.	remains same
Answer» B. increases

112.	What is the order of chemical reaction , if itis found that the reaction rate doubles on doubling the concentration of and also the reaction rate doubles when the concentrations of both & were doubled and quandrupled when the concentrations of both & were doubled ?
A.	1
B.	2
C.	3
D.	4
Answer» C. 3

114.	A space velocity of 5 hr means that
A.	five reactor volumes of feed (at specified conditions) are being fed into the reactor per hour.
B.	after every 5 hours, reactor is being filled with the feed.
C.	cent per cent conversion can be achieved in at least 5 hours.
D.	a fixed conversion of a given batch of feed takes 5 hours.
Answer» B. after every 5 hours, reactor is being filled with the feed.

118.	The concentration of A in a first order reaction, , decreases
A.	linearly with time.
B.	exponentially with time.
C.	very abruptly towards the end of the reaction.
D.	logarithmically with time.
Answer» C. very abruptly towards the end of the reaction.

119.	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
A.	[A].
B.	[B].
C.	[C].
D.	[D].
Answer» E.

120.	The following gas phase reaction is taking place in a plug flow reactor.A stoichiometric mixture of A and B at 300 K is fed to the reactor. At 1 m along the length of the reactor, the temperature is 360 K. The pressure drop is negligible and an ideal gas behaviour can be assumed. Identify the correct expression relating the concentration of A at the inlet (CA0), concentration of A at 1m (CA) and the corresponding conversion of A (X).
A.	[A].
B.	[B].
C.	[C].
D.	[D].
Answer» D. [D].

121.	Consider a reversible exothermic reaction in a plug flow reactor. The maximum and minimum permissible temperatures are Tmax and Tmin respectively. Which of the following temperature (T) profiles will require the shortest residence time to achieve the desired conversion.
A.	[A].
B.	[B].
C.	[C].
D.	[D].
Answer» C. [C].

122.	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
A.	2/3 kW
B.	1kW
C.	5/3 kW
D.	4kW
Answer» D. 4kW

123.	For a series of reactions having k1 << k2, the reaction system can be approximated as
A.	[A].
B.	[B].
C.	[C].
D.	[D].
Answer» E.

124.	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
A.	5°C
B.	10°C
C.	20°C
D.	100°C
Answer» C. 20°C

125.	For a vapour phase catalytic reaction (A + B P) which follows the Ridel mechanism and the reaction step is rate controlling, the rate of reaction is given by (reaction rate is irreversible, product also absorbs).
A.	[A].
B.	[B].
C.	[C].
D.	[D].
Answer» B. [B].

Explore topic-wise MCQs in Chemical Engineering.

Vegetable oils are hydrogenated in a __________ reactor.

The sequence in which three CSTR's of volumes 5, 10 and 15 m will be connected in series to obtain the maximum production in a second order irreversible reaction is

For the reversible reaction 2, 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 ?

If is the quantity of reactants initially present, the quantity left after '' half periods will be equal to

For a __________ order chemical reaction, , the fractional conversion of reactant '' is proportional to time.

The order of the chemical reaction, , whose rate equation is given as -= . is

The decomposition of into is represented by the exothermic reaction, 2. To achieve maximum decomposition, it is desirable to carry out the reaction.

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

For the liquid phase parallel reactions:, = .; = 80 KJ/mole, = 1. ; = 120 KJ/mole The desired product is R. A higher selectivity of R will be achieved, if the reaction is conducted at

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

If = overall order of a chemical reaction. = initial concentration of reactant. = time required to complete a definite fraction of the reaction. Then pick out the correct relationship.

A space velocity of 5 hr means that

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

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

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

The concentration of A in a first order reaction, , decreases

Consider a reversible exothermic reaction in a plug flow reactor. The maximum and minimum permissible temperatures are Tmax and Tmin respectively. Which of the following temperature (T) profiles will require the shortest residence time to achieve the desired conversion.

For a series of reactions having k1 << k2, the reaction system can be approximated as

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

For a vapour phase catalytic reaction (A + B P) which follows the Ridel mechanism and the reaction step is rate controlling, the rate of reaction is given by (reaction rate is irreversible, product also absorbs).

The first order gas phase reaction is conducted isothermally in batch mode. The rate of change of conversion with time is given by

The reaction rate constants at two different temperature T1 and T2 are related by

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?

Which of the following fixes the volume of a batch reactor for a particular conversion and production rate?

In which of the following reactions, thee-quilibrium will shift to the right, if the total pressure is increased?

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 isA. absorption of A.

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

To maximise the formation of R in the simultaneous reactionA + B → R , rR = 2CA0.5.CB2 A + B → S , rS = 1.5 CA . CB We should have

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

In which of the following gaseous phase reversible reactions, the product yield can not be increased by the application of high pressure?

Which of the following curves shows the effect of temperature on the extent of gas-solid adsorption at a given pressure?

What is the order of a chemical reaction whose rate is deter-mined by the variation of one concentration term only?

Which of the following is the optimum operating condition for an exothermic reversible reaction taking place in a plug-flow reactor?

Given, 3H₂ + CO = CH₄ + H₂O, KP = 101.84 and, 4H₂ + CO₂ = CH₄ + 2H₂O, KP = 101.17the KP for the reaction CO + H₂O = CO₂ + H₂ is

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.)

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

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?

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.

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 rR/rS = (k₁/k₂).Csub>Aa-b

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

Effectiveness factor (E) of a catalyst pellet is defined as, E = (actual rate within pore of catalyst/rate if notsnowed by pore diffusion) Effectiveness factor for a first order reaction is given by (where, T = Thiele modulus)

For reaction, P + 2→ 3R, molar rate of consumption of P is

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?

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 ?

126.	The first order gas phase reaction is conducted isothermally in batch mode. The rate of change of conversion with time is given by
A.	[A].
B.	[B].
C.	[C].
D.	[D].
Answer» D. [D].

127.	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)
A.	E
B.	E + ΔHA
C.	E + ΔHA - ΔHR)
D.	ΔHA + ΔHR
Answer» D. ΔHA + ΔHR

128.	The reaction rate constants at two different temperature T1 and T2 are related by
A.	[A].
B.	[B].
C.	[C].
D.	[D].
Answer» C. [C].

129.	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?
A.	A Vs . τ
B.	A Vs ln τ
C.	A/(1 - XA)Vs τ
D.	A(1 - XA)Vs τ
Answer» B. A Vs ln τ

130.	Which of the following fixes the volume of a batch reactor for a particular conversion and production rate?
A.	perating conditions (e.g. pressure and temperature)
B.	ate constant
C.	ensity of mixture
D.	one of these
Answer» D. one of these

131.	In which of the following reactions, thee-quilibrium will shift to the right, if the total pressure is increased?
A.	₂ + Cl₂ ⇋ 2HCl
B.	₂ + O₂ ⇋ 2NO
C.	₂O₄ ⇋ 2 NO₂
D.	₂ + I₂ ⇋ 2HI
Answer» C. ₂O₄ ⇋ 2 NO₂

132.	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 isA. absorption of A.
A.	bsorption of A
B.	urface reaction between absorbed A and absorbed B
C.	urface reaction between absorbed A and B in the gas phase
D.	urface reaction between A in the gas phase and absorbed B
Answer» D. urface reaction between A in the gas phase and absorbed B

133.	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
A.	/3
B.	/8
C.	/3
D.	/8
Answer» C. /3

134.	To maximise the formation of R in the simultaneous reactionA + B → R , rR = 2CA0.5.CB2 A + B → S , rS = 1.5 CA . CB We should have
A.	ow CA, low CB
B.	ow CA, high CB
C.	igh CA, low CB
D.	igh CA, high CB
Answer» C. igh CA, low CB

135.	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
A.	/2
B.	/3
C.	/4
D.	/5
Answer» D. /5