Chemical Reactions Engineering Part 3 Flashcards
For the same residence time, which one will give the maximum conversion ?
Single stirred tank (v = 5 litres).
Two stirred tank (each of 2.5 litres) in series.
Stirred tank followed by tubular flow reactor (each of 2.5 litres).
Single tubular flow reactor (v = 5 litres).
Single tubular flow reactor (v = 5 litres).
__________ gas is normally employed in B.E.T.method of finding out the surface area of catalyst.
N2
H2
CO2
He
N2
The exit age distribution curve E(t) for an ideal CSTR with the average residence time, T, is given by
e^-t/T
[(e^-t/T)/T]
1 - e^-t/T
1-[(e^-t/T)/T]
[(e^-t/T)/T]
etTT
The rate constant of a reaction depends on the
initial concentration of reactants.
time of reaction.
temperature of the system.
extent of reaction.
temperature of the system.
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 ?
0.253
0.338
0.152
0.637
0.338
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
CSTR of volume V
PFR of volume V
CSTR of volume V/X
PFR of volume V/X
PFR of volume V
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.
3
4
6
8
4
For a __________ order reaction, the units of rate constant and rate of reaction are the same.
zero
first
second
fractional
zero
In case of staged packed bed reactors carrying out exothermic reaction, use
high recycle for pure gas.
plug flow for dilute liquid requiring no large preheating of feed.
cold shot operations for a dilute solution requiring large preheating to bring the stream upto the reaction temperature.
all (a), (b) and (c).
all (a), (b) and (c).
Vegetable oils are hydrogenated in a __________ reactor.
slurry
plug flow
homogeneous catalytic
none of these
slurry
veg oil slurry
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
1/2
1/3
1/4
1/5
1/3
gas 50% A3B 1/3 mole fraction
The rate of reaction does not decrease appreciably as the reaction proceeds in case of __________ reactions.
autocatalytic
exothermic
endothermic
autothermal
autocatalytic
For all positive reaction orders for a particular duty,
mixed reactor is always larger than the plug-flow reactor.
ratio of the volume of the mixed reactor to that of the plug-flow reactor decreases with order.
reactor size is independent of the type of flow.
density variation during reaction affects design.
mixed reactor is always larger than the plug-flow reactor.
The heat of reaction
depends on the pressure only.
depends on the mechanism of reaction only.
depends on both pressure and mechanism of reaction.
is independent of the mechanism of reaction.
is independent of the mechanism of reaction.
Which of the following does not produce a change in the value of rate constant of a reaction ?
Pressure
Temperature
Concentration and catalyst
None of these.
Concentration and catalyst
With increase in temperature, the equilibrium conversion of a reversible exothermic reaction
decreases
increases
remains unaffected
decreases linearily with temperature
decreases
In a CSTR __________ varies with time.
reaction rate
concentration
both (a) & (b)
neither (a) nor (b)
neither (a) nor (b)
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.) ?
1/3
1/2
2/3
2
2/3
As the chemical reaction proceeds, the rate of reaction
increases.
decreases.
remains same.
may increase or decrease depending on the type of reaction.
decreases.
Pick out the wrong statement.
A catalyst does not alter the final position of equilibrium in a reversible reaction.
A catalyst initiates a reaction.
A catalyst is specific in reaction.
A catalyst remains unchanged in chemical composition at the end the reaction.
A catalyst initiates a reaction.
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.
more than
less than
same as
data insufficient; can’t be predicted.
same as
1 0.5 10 5 same as
Photo-chemical reactions occur in presence of
sunlight.
darkness.
solid catalysts.
monochromatic radiation only.
sunlight.
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/n
V
V.n
1/V
V
Knudsen diffusion is directly proportional to
T
sqrt(T)
1/sqrt(T)
T^2
sqrt(T)