Common data for the following two questions
The
following gas phase reaction are carried out isothermally in a CSTR
A→2R;
r1 = k1PA; k1 = 20 mol/(s-m3-bar)
A→3R;
r2 = k2PA; k2 = 40 mol/(s-m3-bar)
Total
pressure = 1 bar, FA0 = 1 mol/s; feed is pure A
The
volume of CSTR required for a fractional conversion equal to 0.3 due to the
first reaction is
(A)
0.011
(B)
0.021
(C)
0.275
(D)
0.375
GATE 2003
Answer: (B)
What is the
maximum possible value of FR (mol/s)?
(A)
1/3
(B)
½
(C)
2/3
(D)
2
GATE 2003
Answer: (C)
A liquid phase
reaction is to be carried out under isothermal. The reaction rate a function of
conversion has been determined experimentally and is shown in 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?
(A)
CSTR followed by a PFR
(B)
PFR followed by a CSTR
(C)
CSTR followed by a PFR followed by a
CSTR
(D)
PFR followed by a CSTR followed by a PFR
GATE
2003
Answer: (D)
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 kmol/m3, XA = 0.5
Feed temperature
= reactor temperature = 40⁰C, rate constant at 40⁰C = 1 min-1 (ΔH) =
-40 KJ/mol, ρ = 1000 kg/m3, CP = 4 J/g⁰C, 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)
1 kW
(C)
5/3 kW
(D)
4 kW
GATE 2003
Answer: (C)
An
exothermic reaction takes place in an adiabatic reactor. The product
temperature ____________ the reactor feed temperature.
(A)
Is always equal to
(B)
Is always greater than
(C)
Is always less than
(D)
May be greater or less than
GATE
2002
Answer: (B)
The
extent of a reaction is
(A)
Different for reactants and products
(B)
Dimensionless
(C)
Dependent on the stoichiometric
coefficients
(D)
All of the above
GATE 2002
Answer: (A)
For an ideal
plug flow reactor the value of the Peclet number is
(A)
Zero
(B)
Infinity
(C)
1
(D)
10
GATE
2002
Answer: (B)
In the hydro
dealkylation of toluene to benzene, the following reaction 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/per moles of toluene converted) is 90%. The fractional conversion of
hydrogen is
(A)
0.16
(B)
0.144
(C)
0.152
(D)
0.136
GATE 2002
Answer: (C)
A batch
adiabatic reactor at an initial temperature 373 K is being used for the
reaction A → B.
Assume the heat
of reaction is -1 kJ/mol at 373 K and the heat capacity of both A and B to be
constant and equal to 50 J/mol-K. The temperature rise after a conversion of
0.5 will be
(A)
5⁰C
(B)
10⁰C
(C)
20⁰C
(D)
100⁰C
GATE
2002
Answer: (B)
A pulse tracer
is introduced in an ideal CSTR (with mean residence time τ) a time t = 0. The
time taken for the exit concentration of the tracer to reach half of its
initial value will be
(A)
2τ
(B)
0.5τ
(C)
τ/0.693
(D)
0.693τ
GATE
2002
Answer: (D)
The reaction rate constant at two
different temperatures T1 and T2 are related by
GATE
2001
Answer: (B)
The conversion for a second order irreversible
reaction (constant volume)
in batch mode is given by
GATE 2001
Answer: (B)
The first order gas phase reaction
is conducted isothermally in batch mode.
The rate of change of conversion with time is given by
GATE 2001
Answer: (C)
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
(A)
0
(B)
1
(C)
1.5
(D)
2
GATE 2000
Answer: (A)
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 second reactor will
be
(A)
60
(B)
75
(C)
90
(D)
100
GATE 2000
Answer: (B)
The following half life data are
available for the irreversible liquid phase reaction A → products.
Initial
conc. (kmol/m3) Half
life (min)
2 2
8 1
The overall order of the reaction is
(A)
0.5
(B)
1
(C)
1.5
(D)
2
GATE 2000
Answer: (C)
In solid catalyzed reactions the
diffusional effects are more likely to affect the overall rate of reaction for
(A)
Fast reactions in catalysts of small
pore diameter
(B)
Fast reactions in catalysts of large
pore diameter
(C)
Slow reactions in catalysts of small
pore diameter
(D)
Slow reactions in catalyst of large pore
diameter
GATE 2000
Answer: (D)
The experimentally determined overall
order for the reaction
A + B → C + D is two. Then the
(A)
Reaction is elementary with a
molecularity of 2
(B)
Molecularity of the reaction is 2, but
the reaction may not be elementary
(C)
Reaction may be elementary with a
molecularity of 2
(D)
Reaction is elementary but the
molecularity may not be 2
GATE 2000
Answer: (B)
For liquid phase parallel reaction
(A)
Low temperature in a CSTR
(B)
High temperature in a CSTR
(C)
Low temperature in a PFR
(D)
High temperature in a PFR
GATE 2000
Answer: (A)
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 =
-50,000 KJ/kmol of A rejected
Heat capacities CP,A = CP,B
= 100 KJ/kmol.K (may be assumed independent of temperature).
(A)
400
(B)
500
(C)
600
(D)
1000
GATE
2000
