CHEMICAL REACTION ENGINEERING Flashcards
Which of the following will give maximum gas conversion ?
A. Fixed bed reactor.
B. Fluidised bed reactor.
C. Semi-fluidised bed reactor.
D. Plug-flow catalytic reactor.
SEMI-FLUIDIZED BED REACTOR
__________ explains the mechanism of catalysis.
A. Activated complex theory
B. Collision theory
C. Thermodynamics
D. None of these
ACTIVATED COPMPLEX THEORY
From among the following, choose one which is not an exothermic process.
A. Methanol synthesis
B. Catalytic cracking
C. Ammonia synthesis
D. Oxidation of sulphur
CATALYTIC CRACKING
The fractional volume change of the system for the isothermal gas phase reaction, A 3B , between no conversion and complete conversion is
A. 0.5
B. 1
C. 2
D. 3
2
A catalyst
A. initiates a reaction.
B. lowers the activation energy of reacting molecules.
C. is capable of reacting with any one of the reactants.
D. can not be recovered chemically unchanged at the end of a chemical reaction.
LOWERS THE ACTIVATION ENERGY OF REACTING MOLECULE
What is the order of a chemical reaction, A + 2B -> C, 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
B 7/4
C 5/2
D. 5/4
7/2
For high conversion in a highly exothermic solid catalysed reaction, use a __________ bed reactor.
A fixed
B fluidised bed reactor followed by a fixed
C fixed bed reactor followed by a fluidised
D fluidised
FLUIDIZED BED REACTOR FOLLOWED BY A FIXED
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 8
B 12
C 16
D 32
16
The single parameter model proposed for describing non-ideal flow is the __________ model.
TANK IN SERIES AND DISPERSION
A first order reaction requires two equal sized CSTR. The conversion is
A less when they are connected in series.
B more when they are connected in series.
C more when they are connected in parallel.
D same whether they are connected in series or in parallel.
MORE WHEN THEY ARE CONNECTED IN SERIES
In case of physical adsorption, the heat of adsorption is of the order of __________ kcal/kg.mole.
A 100
B 1000
C 10000
D 100000
1000
The most unsuitable reactor for carrying out reactions in which high reactant concentration favours high yields is
A backmix reactor
B plug flow reactor
C series of CSTR
D PFR in series
BACKMIX REACTOR
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 100%
B 95%
C 75%
D 20%
95%
A reactor is generally termed as an autoclave, when it is a
A high pressure batch reactor.
B atmospheric pressure tank reactor.
C high pressure tubular reactor.
D atmospheric pressure CSTR.
HIGH PRESSURE BATCH REACTOR
Pick out the wrong statement A pertaining to space velocity of flow reactors.
A The unit of space velocity is (time)-1 .
B The space velocity of 3 hr-1 means that three reactor volumes of feed at specified conditions are being fed into the reactor every hour.
C The space velocity of 3 hr-1 means that one third reactor volume of feed at specified conditions are being fed into the reactor.
D none of these.
THE SPACE VELOCITY OF 3/HR MEANS THAT ONE THIRD OF REACTOR VOLUME OF FEED AT SPECIFIED CONDITIONS ARE BEING FED INTO THE REACTOR
The rate constant of a chemical reaction decreases by decreasing the
A pressure
B concentration of reactants
C temperature
D duration of reaction
TEMPERATURE
Reaction rate equation for the reaction, R +2S -> IS -dCR/dt = K * Ca * Cs^2 . If S at is present in large excess, what is the order of this reaction?
A zero
B one
C two
D three
ONE
Rate of a gaseous phase reaction is given by, -dPa/dt = K*pA^2 . The unit of rate constant is
A (atm)-1
B (hr)-1
C (atm)-1.(hr)-1
D atm.(hr)-1
(atm)-1.(hr)-1
__________ is the response curve for a step input signal from a reactor.
A S-curve
B C-curve
C I-curve
D none of these
S-CURVE
‘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 pressure
B temperature
C both (a) & (b)
D neither (a) nor (b)
TEMPERATURE
Which of the following is the most suitable for very high pressure gas phase reaction ?
A Batch reactor
B Tubular flow reactor
C Stirred tank reactor
D Fluidised bed reactor
TUBULAR FLOW REACTOR
The reaction between oxygen and organic material is a/an __________ reaction.
A exothermic
B endothermic
C biochemical
D photochemical
EXOTHERMIC
With decrease in temperature, the equilibrium conversion of a reversible endother-mic reaction
A decreases
B increases
C remains unaffected
D increases linearly with temperature
DECREASES
In an exothermic chemical reaction, the reactants compared to the products have
A higher temperature
B more energy
C less energy
D same energy.
MORE ENERGY
For a reaction of the type, , the rate of reaction V -> X -> Y -> Z (- rx) is given by
A (K1+K1)CX
B (K1+K2+K3)CX
C K1CV - K2CX
D (K1-K2)CX
K1CV - K2CX
In a consecutive reaction system A -> B -> Cwhen E1 is much greater than E2, the yield of B increases with the
A increase of temperature.
B decrease of temperature.
C increase in initial concentration of A.
D decrease in initial concentration of A.
INCREASE OF TEMPERATURE
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 decreases.
B increases.
C is at the highest allowable temperature throughout.
D first increases and then decreases.
IS AT THE HIGHEST ALLOWABLE TEMPERATURE THROUGHOUT
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
A 8987°K
B 9210°K
C 8764°K
D 8621°K
9210°K
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.
B a relatively small amount of catalyst can cause the conversion of large amount of reactants which does not mean that catalyst concentration is important.
C the catalyst does not form an intermediate complex with the reactant.
D the surface of the catalyst does not play an important role during reaction.
FREE ENERGY OF ACTIVATION IS LOWERED IN THE PRESENCE OF CATALYST, WHICH REMAINS UNCHANGED AT THE END OF REACTION
A catalyst loses its activity due to
A loss in surface area of the active component.
B agglomeration of metal particles caused by thermal sintering of the solid surface.
C covering of the catalytic active sites by a foregin substance.
ALL A B C
‘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 first
B second
C third
D any
ANY
Specific rate constant for a second order reaction
A is independent of temperature.
B varies with temperature.
C depends on the nature of the reactants.
D both (b) and (c).
VARIES WITH TEMPERATURE AND DEPENDS ON THE NATURE OF THE REACTANTS
For the irreversible elementary reactions in parallel viz X -> Y K2 ; X -> Z K1, the rate of disappearance of ‘X’ is equal to
A CA(K1+K2)
B CA(K1 + K2)/2
C CA . K1/2
D CA . K2/2
CA(K1+K2)
For an isothermal variable volume batch reactor, the following relation is applicable for a first order irreversible reaction.
Cao / (1+ εA Xa) * (dXa/dt) = k
For a zero order chemical reaction, the
A half life period is directly proportion to the initial concentration of the reac-tants.
B plot of products concentration with time is a straight line through the origin.
C products concentration increases linerarly with time.
D all (a), (b) and (c).
ALL A B C
BET apparatus
A measures the catalyst surface area directly.
B operates at very high pressure.
C is made entirely of stainless steel.
D none of these.
NONE OF THESE
Radioactive decay follows __________ order kinetics.
A first
B second
C third
D zero.
FIRST
The excess energy of reactants in a chemical reaction required to dissociate into products is termed as the __________ energy.
A activation
B potential
C binding
D threshold
ACTIVATION
For a solid catalysed chemical reaction, the effectiveness of solid catalyst depends upon the __________ adsorption.
A physical
B chemical
C both (a) and (b)
D neither (a) nor (b)
CHEMICAL
Pick out the correct statement.
A In catalytic reactions, the catalyst reacts with the reactants.
B A catalyst initiates a chemical reaction.
C A catalyst lowers the activation energy of the reacting molecules.
D A catalyst can not be recovered chemi cally unchanged at the end of the chemical reaction.
A CATALYST LOWERS THE ACTIVATION ENERGY OF THE REACTING MOLECULES
The dimensions of rate constant for reaction 3A-> B are (l/gm mole)/min. Therefore the reaction order is
A 0
B 1
C 2
D 3
2
Pick out the correct statement
A Reactions with high activation energies are very temperature sensitive.
B Chemical equilibrium is a static state.
C A photochemical reaction is catalysed by light.
D A chemical reaction occurs when the energy of the reacting molecule is less than the activation energy of the reaction.
REACTIONS WITH HIGH ACTIVATION ENERGIES ARE VERY TEMPERATURE SENSITIVE
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
A 0
B 1
C 2
D 3
2
Sulphuric acid is used as a catalyst in the
A hydrogenation of oils.
B gas phase oxidation of SO2 in chamber process.
C alkylation of hydrocarbons.
D none of these.
ALKYLATION OF HYDROCARBONS
Fractional conversion __________ with increase in pressure for ammonia synthesis reaction i.e., N2 + 3H2 <-> 2NH3.
increases
decreases
remains unchanged
unpredictable from the data
INCREASES
Pick out the wrong statement.
A The vessel dispersion number (D/UL) for plug flow and mixed flow approaches zero and infinity respectively.
B Space time in a flow reactor is a measure of its capacity and is equal to the residence time when the density of reaction mixture is constant.
C Mixed reactor is always smaller than the plug flow reactor for all positive reaction orders for a particular duty.
D In an ideal tubular flow reactor, mixing takes place in radial direction and there is no mixing in logitudinal direction.
Mixed reactor is always smaller than the plug flow reactor for all positive reaction orders for a particular duty.
The reason why a catalyst increases the rate of reaction is that, it
A decreases the energy barrier for reaction.
B increases the activation energy.
C decreases the molecular collision diameter.
D none of these.
DECREASES THE ENERGY BARRIES FOR THE REACTION
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.
A both conversion as well as B concentration are same
conversion in both will be the same but concentrations will be different
C both the conversion as well as concentrations will be different
D none of these.
conversion in both will be the same but concentrations will be different
When the density of the reaction mixture is constant in a chemical reaction, the ratio of the mean residence time to space time is
A > 1
B < 1
C 1
D 0
1
In an ideal tubular-flow reactor
A there is no mixing in longitudinal direction.
B mixing takes place in radial direction.
C there is a uniform velocity across the radius.
D all (a), (b) and (c).
ALL A B C
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?
A 1.6
B 2
C 2.24
D 2.5
2.5
__________ is the controlling step in a highly temperature sensitive fluid-solid non-catalytic reaction.
A Gas film diffusion
B Ash diffusion
C Chemical reaction
D none of these
CHEMICAL REACTION
An autothermal reactor is
A most suitable for a second order reaction.
B most suitable for a reversible reaction.
C completely self-supporting in its thermal energy requirements.
D isothermal in nature.
COMPLETELY SELF-SUPPORTING IN ITS THERMAL ENERGY REQUIREMENTS
The rate constant of a first order reaction depends on the
A concentration of the reactant.
B temperature.
C concentration of the product.
D time.
TEMPERATURE
A reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.
A catalytic
B autocatalytic
C photochemical
D none of these
AUTOCATALYTIC
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
A ∞
B 0
C 1
D > 1
1
Which of the following will favour the reverse reaction in a chemical equilibrium reaction ?
A Increasing the concentration of one of the reactants.
B Increasing the concentration of one or more of the products.
C Removal of at least one of the products at regular interval.
INCREASING THE CONCENTRATION OF ONE OR MORE OF THE PRODUCTS
Conversion increases with increase in temperature in case of a an __________ reaction.
A autocatalytic
B irreversible
C reversible endothermic
D reversible exothermic
REVERSIBLE ENDOTHERMIC
Effective diffusivity (DE) in a catalyst pellet is related to molecular diffusivity (DN) and Knudsen diffusivity (DK) as
1/DE = 1/DN + 1/DK
A photochemical reaction is __________ light.
A initiated by
B accompanied with emission of
C catalysed by
D used to convert heat energy into
INITIATED BY
Pick out the wrong statement.
\A In a batch reactor, which is exclusively used for liquid phase reactions; temperature pressure and composition may vary with time.
B In a semi-batch reactor, one reactant is charged batchwise, while the other reactant is fed continuously.
C In a continuous flow reactor, uniform concentration can not be maintained throughout the vessel even in a well agitated system.
D In a continuous flow reactor, both the reactants and the products flow out continuously.
In a continuous flow reactor, uniform concentration can not be maintained throughout the vessel even in a well agitated system.
In a/an __________ reactor, there is exchange of heat with the surroundings with sizeable temperature variation.
A adiabatic
B isothermal
C non-adiabatic
D none of these.
NON-ADIABATIC
Unreacted core model’ represents the reaction involving
A combustion of coal particles.
B roasting of sulphide ores.
C manufacture of carbon disulphide from elements.
D none of these.
ROASTING OF COAL PARTICLES
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).
-rA = (k *Pa Pb) / (1 + Ka * Pa + Kp Pp)
If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is the __________ diffusion.
A film
B ash layer
C pore
D none of these
FILM
The units of frequency factor in Arhenious equation
A are the same as those of the rate constant.
B depend on the order of the reaction.
C depend on temperature, pressure etc. of the reaction.
D are cycles per unit time.
ARE THE SAME AS THOSE OF THE RATE CONSTANT
Which of the following is not a chemical step in a fluid solid catalytic reaction ?
A Surface chemical reaction
B Adsorption
C Desorption
D None of these
NONE OF THESE
For a series of reactions A-> K1 B -> C K2 having k1 «_space;k2, the reaction system can be approximated as
A -> K1 C
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:
A K3 = K1.K2
B K3 = (K1.K2)0.5
C K3(K1+K2)/2
D K3 = (K1.K2)2
K3 = K1.K2
In case of __________ reactions, the reaction rate does not decrease appreciably as the reaction proceeds.
A catalytic
B parallel
C series
D auto catalytic
AUTO CATALYTIC
For nearly isothermal operation involving large reaction time in a liquid-phase reaction, the most suitable reactor is a __________ reactor.
A stirred tank
B tubular flow
C batch
D fixed bed
STIRRED TANK
What is the Thiele modulus of the solid catalysed first order reaction, X _. K Y, if the pore diffusion offers negligible resistance to reaction ?
A < 5
B < 0.5
C > 1
D 5
< 0.5
B.E.T. method can be used to determine the __________ of a porous catalyst.
A solid density
B pore volume
C surface area
D all (a), (b) and (c)
SURFACE AREA
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
A 0
B 1
C 2
D 3
1
Which of the following is an independent variable for a batch tank reactor with uniform concentration and temperature ?
A Time
B Useful volume of the tank
C Diameter of the reactor
D None of these
TIME
For reactions in parallel viz A -> P (desired product) and A -> Q (unwanted product), if the order of the desired reaction is higher than that of the undesired reaction, a
A batch reactor is preferred over a single CSTR for high yield.
B tubular reactor is preferred over a single CSTR for high yield.
C both (a) and (b).
D single CSTR is the most suitable.
BOTH A AND B
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.
A 8
B 16
C 1/8
D 1/16
16
In a reversible chemical reaction having two reactants in equilibrium, if the concentration of the reactants are doubled, then the equilibrium constant will
A remain the same
B be halved
C also be. doubled
D become one fourth
REMAIN THE SAME
The equilibrium constant of a catalytic chemical reaction __________ due to the presence of a catalyst.
A increases
B decreases
C remains unaffected
D unpredictable from the data
REMAINS UNAFFECTED
The rate constant of a chemical reaction increases by increasing the
A temperature
B pressure
C reactant’s concentration
D none of these
TEMPERATURE
The catalytic activity of enzymes is due to their capacity to lower the __________ energy.
A activation
B potential
C kinetic
D none of these
ACTIVATION
A first order reaction requires two unequal sized CSTR. Which of the following gives higher yield ?
A Large reactor followed by smaller one.
B Smaller reactor followed by larger one.
C Either of the arrangement (a) or (b) will give the same yield.
D Data insufficient, can’t be predicted.
Either of the arrangement (a) or (b) will give the same yield.
Pick out the correct statement.
A A lower temperature favours the reaction of lower activation energy.
B The dispersion number for a reactor/vessel is uL/D.
C The rate controlling step in a reaction involving many steps is the fastetst step.
D Pore volume and porosity of a catalyst is measured by Brunaver-Emmet-Teller (BET) technique.
A lower temperature favours the reaction of lower activation energy.
The effect of increasing pressure on the gaseous equilibrium of the reaction 2X+3Y <-> 3X+2Y indicates that
A pressure has no effect.
B backward reaction is favoured.
C forward reaction is favoured.
D none of these.
PRESSURE HAS NO EFFECT
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
A (1 + x)
B (1 - x)
C (1 + x)2
D (1 - x)2
(1 + x)
A batch reactor is characterised by
A constant residence time.
B variation in extent of reaction and properties of the reaction mixture with time.
C variation in reactor volume.
D very low conversion.
variation in extent of reaction and properties of the reaction mixture with time.
When a catalyst increases the rate of forward reaction, the value of rate constant
A increases
B decreases
C remain same
D becomes infinite
INCREASES
Rate determining step in a reaction consisting of a number of steps in series is the __________ step.
A fastest
B slowest
C intermediate
D data insufficient; can’t be predicted
SLOWEST
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.
A 256
B 512
C 112
D 612
512
A catalyst in a chemical reaction __________ free energy change in the reaction.
A increases
B decreases
C either (a) or (b); depends on the type of catalyst
D neither (a) nor (b).
either (a) or (b); depends on the type of catalyst
Signal normally used to study non-ideal flow by stimulus response technique is __________ input.
A pulse
B step
C both (a) & (b)
D neither (a) nor (b).
PULSE AND STEP
When all the limiting reactant is consumed in the reaction, the operational yield __________ the relative yield.
A is greater than
B is smaller than
C equals
D can be either greater or smaller than (depends on the type of reaction)
EQUALS
The half life period of a first order reaction is
A always the same irrespective of the reaction.
B independent on initial concentration of the reactants.
C proportional to the initial concentration of reactants.
D half the specific rate constant.
independent on initial concentration of the reactants.
The catalyst in a second order reversible reaction increases the rate of the forward reaction
A and decreases that of backward reaction.
B and backward reaction equally.
C only.
D to a greater extent than that of the backward reaction.
AND BACKWARD REACTION EQUALLY
Catalyst carriers
A have very high selectivity.
B increase the activity of a catalyst.
C provide large surface area with a small amount of active material.
D inhibit catalyst poisoning.
PROVIDE LARGE SURFACE AREA WITH A SMALL AMOUNT OF ACTIVE MATERIAL
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.
A 0.15
B 0.30
C 0.60
D 0.90
0.6
A high space velocity means that a given
A reaction can be accomplished with small reactor.
B conversion can be obtained with a high feed rate.
C both (a) and (b).
D none of these.
BOTH A AND B
In flow reactors, the performance equations interrelate the rate of reaction to the
A feed rate.
B reactor volume,
C extent of reaction.
D all (a), (b) and (c).
ALL A B C
Space velocity
A describes the extensive operating characteristics of a tubular flow reactor.
B is the maximum feed rate pre unit volume of reactor for a given conversion.
C is a measure of the ease of the reaction.
D all (a), (b) and (c)
ALL A B C
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 ?
A 0.5
B 1
C 0
D 2
1
A reaction which is catalysed by a base is catalysed by all substances which have a tendency to
Alose a proton
B gain a proton
C gain an electron
D none of these
GAIN A PROTON
For a homogeneous reaction of nth order, the dimension of the rate constant is given by
A l/(time)n
B (concentration)1 - n/(time)
C (concentration)n - 1/(time)
D none of these
(concentration)1 - n/(time)
The fractional volume change between no conversion and complete conversion, for the isothermal gas phase reaction, 2A R, is
A 0.5
B -0.5
C 1
D 1.5
-0.5
The reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.
A biochemical
B photochemical
C catalytic
D autocatalytic
AUTOCATALYTIC
A typical example of an exothermic reversible reaction conducted at high pressure in industry is
A dehydration of ethanol.
B methanol synthesis.
C reformation of methane.
D polymerisation of ethylene.
DEHYDRATION OF ETHANOL
Study of chemical kinetics is the easiest in the case of __________ reactions.
A irreversible
B reversible
C surface
D side
IRREVERSIBLE
In autocatalytic reactions,
A one of the reactants acts as a catalyst.
B one of the products acts as a catalyst.
C catalysts have very high selectivity.
D no catalyst is used.
ONE OF THE PRODUCTS ACTS AS CATALYST
Semibatch reactor is preferred, when a/an
A a highly exothermic reaction is to be controlled.
B undersirable side reaction (at high concentration of one of the reactants) is to be avoided.
C a gas is to be reacted with liquid (e.g. hydrogenation of fat).
D all (a), (b), and (c).
ALL A B C
Exposure of a photographic plate to produce a latent image is an example of __________ reaction.
A very slow
B very fast
C photochemical
D both (b) and (c)
VERY FAST AND PHOTOCHEMICAL
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
A 1
B >1
C ∞
D ≥1
∞
Helium-mercury method is used for the measurement of the __________ of the catalyst.
A surface area
B porosity
C pore volume
D both (b) & (c).
POROSITY AND PORE VOLUME
What is the order of a chemical reaction whose rate is deter-mined by the variation of one concentration term only ?
A zero
B first
C second
D third
FIRST
Pick out the wrong statement.
A Visible radiation provides the necessary activation energy in photochemical reactions.
B The order and molecularity of a complex reaction may not be the same.
C For a second order reaction, the slope of the graph/plot between rate and (concentration) is equal to the rate constant (k).
D Molecularity of the reaction is always a whole number greater than zero.
THE ORDER AND MOLECULARITY OF A COMPLEX REACTION MAY NOT BE THE SAME
The rate at which a chemical substance reacts is proportional to its
A active mass
B equivalent weight
C molecular weight
D none of these
ACTIVE MASS
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 is
A 0
B 1
C ∞
D 2π
1
A plug-flow reactor is characterised by
A high capacity.
B presence of axial mixing.
C presence of lateral mixing.
D constant composition and temperature of reaction mixture.
PRESENCE OF LATERAL MIXING
Three plug flow reactors (PFR’s) of 4, 5 & 6 m3 volumes are arranged in two branches as shown below in the figure.
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.
A 100
B 150
C 200
D 225
100
For a tubular reactor with space time ‘τ’ and residence time ‘θ’, the following statement holds good.
A τ and θ are always equal.
B τ = θ , when the fluid density changes in the reactor.
C τ = θ , for an isothermic tubular reactor in which the density of the process fluid is constant.
D τ = θ , for a non-isothermal reactor.
τ = θ , for an isothermic tubular reactor in which the density of the process fluid is constant.
Rate of an autocatalytic chemical reaction is a function of
A temperature only.
B pressure only.
C composition only.
D all (a), (b) and (c).
TEMPERATURE, PRESSURE, AND COMPOSTION
Which of the following curves shows the effect of temperature on the extent of gas-solid adsorption at a given pressure ?
A Langmuir adsorption isotherm
B Adsorption isobar
C Freundlich adsorption isotherm
D None of these
ADSORPTION ISOBAR
For an ideal mixed flow reactor (CSTR), the exit age distribution E(t) is given by
A a dirac delta function
B a step function.
C a ramp function.
D none of the above
NONE OF THE ABOVE
Fluid flow in a real packed bed can be approximated as __________ model.
A plug flow
B dispersion
C mixed flow
D tank in series
DISPERSION
For series reaction, the relative yield
A is always greater for plug-flow reactor than for the single CSTR of the same volume.
B statement in (a) is wrong.
C decreases with increasing conversion.
D both (a) and (c) hold good.
is always greater for plug-flow reactor than for the single CSTR of the same volume.
decreases with increasing conversion.
The ‘E’ curve for a non-ideal reactor defines the fraction of fluid having age between t and t + dt
A at the inlet
B at the outlet
C in the reactor
D averaged over the inlet and outlet
AT THE OUTLET
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
A low CA, low CB
B low CA, high CB
C high CA, low CB
D high CA, high CB
low CA, high CB
A reaction which is catalysed by an acid is also catalysed by any substance, which has a tendency to
A lose a proton.
B gain a proton.
C lose an electron
D none of these.
LOSE A PROTON
A stirred tank reactor compared to tubular-flow reactor provides
A more uniform operating conditions.
B permits operation at the optimum temperature for a long reaction time.
C higher overall selectivity for a first order consecutive reaction.
D all (a), (b) and (c)
ALL A B C
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
A 0.33
B 0.5
C 1
D data insufficient, can’t be predicted
1
A catalyst inhibitor
A lessens its selectivity.
B may be useful for suppressing undesirable side reactions.
C is added in small quantity during the catalyst manufacture itself.
D all(a), (b) and (c).
ALL A B C
In chamber process of sulphuric acid manufacture in industry, the gas phase oxidation of SO2 to SO3 is accomplished by a __________ reaction.
A non-catalytic homogeneous
B non-catalytic heterogeneous
C catalytic homogenous
D catalytic heterogeneous
CATALYTIC HOMOGENOUS
If the rate of a chemical reaction becomes slower at a given temperature, then the
A initial concentration of the reactants remains constant.
B free energy of activation is lower.
C entropy changes.
D free energy of activation is higher.
FREE ENERGY OF ACTIVATION IS HIGHER
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 XA Vs . τ
B XA Vs ln τ
C XA/(1 - XA)Vs τ
D XA(1 - XA)Vs τ
XA Vs . τ
The rate of the reaction, X Y, quadruples when the concentration of ‘X’ is doubled. The rate expression for the reaction is, r = K Cxn, the value of ‘n’ in this case will be
A 0
B 1
C 2
D 3
2
The value of steric factor ‘P’ in the equation k = PZeE/RT usually ranges from
A l.0 to 10-8
B l.l.to 102
C 0.1 to 0.9
D none of these
l.0 to 10-8
For a zero order reaction, the concentration of product increases with the
A increase of reaction time.
B increase in initial concentration.
C total pressure.
D decrease in total pressure.
INCREASE OF REACTION TIME
Pick out the wrong statement.
A ‘Hold back’ is defined as the fraction of material that stays longer than the mean residence time.
B Study of non-ideal flow reactor is done experimentally by stimulus-response technique.
C For studying a chemical reaction, it is desirable to monitor the reactants during initial stages and the products during the final stages of reaction.
D A batch reactor can not be used to study the kinetics of catalytic reaction.
A batch reactor can not be used to study the kinetics of catalytic reaction.
Effectiveness factor of a catalyst pellet is a measure of the __________ resistance.
A pore diffusion
B gas film
C chemical reaction
D none of these
PORE DIFFUSION
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»_space; (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
E + ΔHA - ΔHR)
Given,
3H2 + CO = CH4 + H2O, KP = 10^1.84 and,
4H2 + CO2 = CH4 + 2H2O, KP = 10^1.17
the KP for the reaction CO + H2O = CO2 + H2 is
A 10^3.01
B 10^-0.67
C 10^-3.01
D l0^0.67
l0^0.67
Differential method for analysing the kinetic data is used
A for testing complicated mechanisms.
B when the data are scattered.
C when rate expressions are very simple.
D none of these.
FOR TESTING COMPLICATED MECHANISM
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
A more
B less
C same
D either (a) or (b), depends on other factors
SAME
The reaction in which the rate equation corresponds to a stoichiometric equation, is called a/an __________ reaction.
A elementary
B non-elementary
C parallel
D autokinetic
ELEMENTARY
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
0
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
Arrhenious equation represents graphically the variation between the __________ and temperature.
A rate of reaction
B frequency factor
C rate constant
D activation energy
RATE CONSTANT
__________ catalytic reaction is involved in the thermal cracking of gas oil.
A Homogeneous
B Homogeneous non
C Heterogeneous
D Heterogeneous non
HOMOGENEOUS
Variables affecting the rate of homogeneous reactions are
A pressure and temperature only.
B temperature and composition only.
C pressure and composition only.
D pressure, temperature and composition.
PRESSURE, TEMPERATURE AND COMPOSITION
A chemical reaction occurs when the energy of the reacting molecules is __________ the activation energy of the reaction.
A less than
B equal to
C more than
D equal to or more than
EQUAL TO OR MORE THAN
Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction ?
A Ash resistance.
B Gas film and pore surface diffusion resistances for reactants.
C Surface phenomenon resistance.
D Gas film and pore surface diffusion resistances for products.
ASH RESISTANCE
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
A zero
B one
C two
D three
ONE
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
10°C
If CA is the quantity of reactants initially present, the quantity left after ‘n’ half periods will be equal to
(1/2)^N * CA
A photochemical reaction is
A accompanied with emission of light.
B catalysed by light.
C initiated by light.
D all (a), (b) & (c).
CATALYZED BY LIGHT
The rate controlling step for the heterogeneous irreversible catalytic reaction A(g) + B(g) C(g) is the surface reaction of absorbed A with absorbed B to give adsorbed C. The rate expression for this reaction can then be written as (where, KA, KB and KC are the equilibrium constants and is the rate constant of the rate controlling step.)
(KKAKBPAPB)/ (1+KAPA+KBPB+KC*PC)^2
The optimum performance for reactors operating in parallel is obtained when the feed stream is distributed in such a way, that the
A space time for each parallel line is same.
B space time for parallel lines is different.
C larger reactors have more space time compared to smaller ones.
D none of these.
SPACE TIME FOR EACH PARALLEL LINE IS SAME
A catalyst is said to be a negative catalyst, if it
A retards the rate of reaction.
B reduces the value of equilibrium constant.
C does not initiate the reaction.
D all (a), (b) and (c).
RETARDS THE RATE OF REACTION
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.
A film diffusion
B diffusion through ash layer
C chemical reaction
D either (a), (b) or (c)
CHEMICAL REACTION
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
A 100
B 97.5
C 95
D 2.5
100
The conversion for a second order, irreversible reaction (constant volume), A -> K2 B , in batch mode is given by
(K2 * CAO * T)/ (1 + K2 * CAO * T)
Pick out the wrong statement.
A The integral method of analysing kinetic data is used when the data is scattered.
B The differential method of analysing kinetic data requires more accurate or larger amounts of data.
C When the reaction rate is independent of temperature, the reaction is said to be of zero order.
D The ratio of volumes of plug flow reactor to that of mixed reactor is always less than one for identical feed composition, flow rate, conversion and for all positive reaction orders.
When the reaction rate is independent of temperature, the reaction is said to be of zero order.
A backmix reactor
A is same as plug-flow reactor.
B is same as ideal stirred tank reactor.
C employs mixing in axial direction only.
D is most suitable for gas phase reaction.
IS SAME AS IDEAL STIRRED TANK REACTOR
Rate of a chemical reaction is not influenced by the
A catalyst
B temperature
C reactants concentration
D number of molecules of reactants taking part in a reaction
NUMBER OF MOLECULES OF REACTANCT TAKING PART IN A REACTION
Pick out the wrong statement:
A Chemical reactions with high activation energy are very temperature sensitive.
B A flat velocity profile exists in a plug flow reactor.
C The residence time for all the elements of fluid in case of a P.F.R. need not be same.
D Half life of a reaction increases with increased initial concentration for reaction orders more than one.
The residence time for all the elements of fluid in case of a P.F.R. need not be same.
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))
A 400
B 500
C 600
D 1000
600
Which of the following is not a theory of homogeneous reaction?
A Collision theory and activated complex theory
B Chain reaction theory
C Radiation hypothesis
D None of these
NONE OF THESE
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?
III, II, I
In a semi-batch reactor,
A mixing takes place in axial direction only.
B velocity of reaction can be controlled.
C condition similar to plug flow reactor exists.
D residence time is constant.
VELOCITY OF REACTION CAN BE CONTROLLED
Most important characteristics of gas-liquid reactors are the
SPECIFIC INTERFACIAL AREA AND LIQUID HOLD UP
Which of the following is a controlling factor in very fast heterogeneous reaction ?
A Heat and mass transfer effects
B Pressure
C Temperature
D Composition of reactant
HEAT AND MASS TRANSFER EFFECTS
Enzymes are destroyed, when the
A temperature is very high,
B reactant’s concentration is very high.
C reactant’s concentration is very low.
D reaction rate is independent of the reactant’s concentration.
TEMPERATURE IS VERY HIGH
For an autocatalytic reactor, the suitable reactor set up is
A P.F. reactors in series.
B CSTR in series.
C CSTR followed by P.F. reactor.
D P.F. reactor followed by CSTR.
CSTR followed by P.F. reactor.
Ionic reactions occur in
A solid state only
B liquid state only
C solutions
D any state
SOLUTIONS
Sometimes, batch process is preferred over continuous process, when the product
A quality & yield can not be achieved in continuous processes, because of long residence time.
B sales demand is fluctuating.
C both (a) & (b).
D neither (a) nor (b).
quality & yield can not be achieved in continuous processes, because of long residence time.
sales demand is fluctuating.
In a chemical reaction X + Y + Z -> K P , 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?
A Zeroth order
B First order
C Second order
D Third order
THIRD ORDER
The half life period of a first order reaction is given by (where, K = rate constant. )
A 1.5K
B 2.5 K
C 0.693/K
D 6.93 K
0.693/K
Half life period of a chemical reaction is
A the time required to reduce the concentration of the reacting substance to half its initial value.
B half of the space time of a reaction.
C half of the residence time of a reaction.
D none of these
the time required to reduce the concentration of the reacting substance to half its initial value.
In the gaseous phase ammonia formation reaction (N2 + 3H2 <-> 2NH3), the value of the equilibrium constant depends on the
A total pressure of the system.
B volume of the reactor.
C temperature.
D initial concentration of N2 and H2.
TEMPERATURE
Transition state theory relates the above quantities as
A k ∝ e-E/RT
B k ∝ T.eE/RT
C k ∝ T
D k ∝ T1.5
k ∝ T.eE/RT
Photochemical reaction rate does not depend significantly on temperature, because
A it is a reversible reaction.
B it is an exothermic reaction.
C the energy of reacting molecules exceeds the activation energy by absorption of light.
D none of these.
the energy of reacting molecules exceeds the activation energy by absorption of light.
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
5/2 kW
According to the ‘law of mass action’, the rate of reaction is directly proportional to the
A equilibrium constant.
B volume of the reaction vessel.
C nature of the reactants.
D molar concentration of the reactants.
molar concentration of the reactants.
In a chemical reaction, __________ are conserved.
A ions
B masses
C atoms
D both(b) & (c)
ATOMS AND MASSES
For an ideal gas mixture undergoing a reversible gaseous phase chemical reaction, the equilibrium constant
A is independent of pressure.
B increases with pressure.
C decreases with pressure.
D increases /decreases with pressure depending on the stoichiometric co-efficients of the reaction.
increases with pressure.
In the reversible reaction of the type, A + B <-> AB, in general
A both forward and backward reactions will be exothermic.
B neither of the reactions will be en-dothermic.
C the combination reaction will be exothermic, while the dissociation reaction will be endothermic.
D the combination reaction will be endothermic, while the dissociation reaction will be exothermic.
the combination reaction will be exothermic, while the dissociation reaction will be endothermic.
A batch reactor is
A suitable for gas-phase reactions on commercial scale.
B suitable for liquid phase reactions involving small production rate.
C least expensive to operate for a given rate.
D most suitable for very large production rate.
suitable for liquid phase reactions involving small production rate.
For a first order reaction carried out in a plug flow reactor, the space time is
1/K LN CO/C
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
A 2
B 4
C 11
D 22
11
A chemical reaction is of zero order, when the reaction rate is (where, CA = concentration of reactant)
A ∝ CA.
B ∝ 1/CA.
C independent of temperature.
D none of these.
NONE OF THESE
Second order consecutive irreversible reactions A -> K1 B -> K2 C 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)?
A 1/4
B 1/2
C 2
D 4
1/4
Pick out the wrong statement.
A Catalytic activity of enzyme catalysed reactions which is affected by temperature, pH value & chemical agents, is maximum at a temperature of about 45°C.
B Most of the enzyme catalysed reactions involve at least two substrates.
C Enzymes help in increasing the activation energy of the reaction.
D Equilibrium concentrations in enzyme catalysed reactions can be calculated by using the thermodynamic properties of substrates & products.
Enzymes help in increasing the activation energy of the reaction.
There is no correspondence between stoichiometry and the rate equation in case of a/an __________ reaction.
A elementary
B multiple
C autocatalytic
D non-elementary
NON-ELEMENTARY
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?
A Inner catalyst core of radius R/8 does not participate in reaction.
B Inner catalyst core of radius R/2 does not participate in reaction.
C Inner catalyst core of radius 7R/8 does not participate in reaction.
D Effectiveness factor for a zero order reaction can not be 7/8 as it must always be 1.
Inner catalyst core of radius R/8 does not participate in reaction.
Which of the following is used for calcination of limestone and dolomite in industrial practice ?
A Fluidised bed reactor
B Moving bed reactor
C Fixed bed reactor
D None of these
MOVING BED REACTOR
An imbalanced chemical reaction equation is against the law of
A multiple proportion
B conservation of mass
C constant proportion
D none of these
CONSERVATION OF MASS
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 ?
A 1
B 2
C 3
D 0
1
Which of the following is a characteristic of an ideal plug flow reactor ?
A Axial dispersion
B Flat velocity profile
C Uniform mixing
D None of these
FLAT VELOCITY PROFILE
Velocity of a reaction depends upon the
A nature of the reactants.
B concentration of the reactants.
C temperature at which the reaction is carried.
D all (a), (b) and (c).
ALL A B C
Threshold energy in a reaction is equal to the
A activation energy
B normal energy of reactants
C sum of (a) & (b)
D neither (a) nor (b)
SUM OF ACTIVATION ENERGY AND NORMAL ENERGY OF REACTANTS
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
A 0.80
B 1.33
C 1.60
D 2.67
1.6
Design of heterogeous catalytic reactor involves consideration of __________ steps.
A only chemical
B only physical
C both (a) & (b)
D neither (a) nor (b)
CHEMICAL AND PHYSICAL
A consecutive reaction, , is characterised by A -> C1 B -> C2 B
A maxima in the concentration of A.
B maxima in the concentration of B.
C maxima in the concentration of C.
D high exothermicity.
maxima in the concentration of B.
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 Litre/mole.second
B Moles/litre.second
C Litre/mole
D Litre/second
Litre/mole.second
For a fluidised bed reactor, the most suitable/relevant model is a __________ model.
A tank in series
B bubbling bed
C plug flow
D none of these
BUBBLING BED
The rate at which a chemical substance reacts is proportional to its
A active mass
B molecular weight
C equivalent weight
D atomic weight
ACTIVE MASS
In a reaction, the threshold energy is equal to (where, A = activation energy N = normal energy of reactants)
A A
B N
C A+N
D A-N
A + N
Thermodynamic equilibrium constant in a system is affected by
A inerts
B pressure
C temperature
D all (a), (b) & (c)
TEMPERATURE
The most suitable reactor for carrying out an auto-thermal reaction is a
A batch reactor
B CSTR
C semi-batch reactor
D plug-flow reactor
CSTR
Which of the following chemical reactions will be favoured by low pressure ?
A 2HI <-> H2 + I2
B N2O2 <-> 2NO2
C N2 + O2 <-> 2NO
D none of these
N2O2 <-> 2NO2
A catalyst in a chemical reaction
A decreases the activation energy.
B alters the reaction mechanism.
C increases the frequency of D collisions of reacting species.
all (a), (b) and (c).
ALL A B C
Slurry reactors are characterised by the
A lack of intraparticle diffusion resistance.
B presence of two mobile phases.
C both (a) and (b).
D neither (a) nor (b).
lack of intraparticle diffusion resistance.
presence of two mobile phases.
Limiting reactant in a chemical reaction decides the
A rate constant
B conversion
C reaction speed
D equilibrium constant.
CONVERSION
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 ?
A CA0 Vs t1/2
B ln CA0 Vs t1/2
C CA0 Vs ln t1/2
D ln CA0 Vs ln t1/2
CA0 Vs ln t1/2
The rate of forward reaction, at chemical equilibrium is____the rate of backward reaction.
A more than
B less than
C equal to
D either (b) or (c)
EQUAL TO
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)* Ca^(a-b) .
A use high pressure and eliminate inerts, when a > b.
B avoid recycle, when a > b.
C use batch reactor or plug flow reactor, when a > b.
D use CSTR with a high conversion, when a > b.
avoid recycle, when a > b.
With increase in temperature, the equilibrium __________ rises in case of endothermic reaction.
A constant
B conversion
C both (a) & (b)
D neither (a) nor (b)
CONVERSION
n case of a consecutive unimolecular type first order reaction A -> K1 R -> K2 S, the concentration of component __________ increases continuously with time.
A S
B R
C A
D none of these
S
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
A blood
B saliva
C intestine
D gland
SALIVA
Considering the endotheomic dissociation of CaCO3 in a closed vessel (CaCO3 <-> CaO + CO2), the pressure of CO2 increases, if
A a catalyst is added.
B the temperature is increased.
C an inert gas is pumped keeping the temperature constant.
D none of these.
THE TEMPERATURE IS INCREASED
The exit age distribution of fluid leaving a vessel is used to know the
A activation energies of a reaction.
B reaction mechanism.
C extent of non-ideal flow in the vessel.
D none of these.
EXTENT OF NON-IDEAL FLOW IN THE VESSEL
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
A k cal
B k cal/°K
C °K
D k cal. °K
°K
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 (A) increases (B) decreases
B (A) decreases (B) increases
C (A) increases (B) increases
D (A) decreases (B) decreases
(A) decreases (B) increases
For the irreversible elementary first order reaction in parallel viz. X -> K1 Y , X -> K2 Y , a plot of Cy Vs. Cz will give a straight line having a slope of
A K2/K1
B K1/K2
C K1 . K2
D K1 + K2
K1/K2
The time needed to achieve the same fractional conversion for particles of different sizes (d) when chemical reaction controls, is proportional to
A d
B d
C d1.5
D d2
d
A balanced chemical reaction equation conforms to the law of
A conservation of mass
B Avagadro’s hypothesis
C gaseous volumes
D none ofthese
CONSERVATION OF MASS
An exothermic reaction takes place in an adiabatic reactor. The product temperature __________ 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
IS ALWAYS GREATER THAN
Reverse reaction in a chemical equilibrium is favoured by the
A removal of one of the products regularly.
B increase in the concentration of oneof the products.
C increase in the concentration of one of the reactants.
D none of these.
INCREASE IN THE CONCENTRATION OF ONE OF THE PRODUCTS
The equilibrium constant for the reversible reaction, A-> K1 P, A<-K2 P , is affected by the
A temperature of the system.
B presence or absence of inerts.
C pressure of the system.
D kinetics of the reaction.
PRESSURE OF THE SYSTEM
Sum of the powers of the concentration terms in the rate equation is called the __________ of the reaction.
A order
B overall order
C molecularity
D none of these
OVERALL ORDER
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
A temperature is increased.
B pressure is reduced.
C temperature is increased and pressure is reduced.
D temperature is reduced and pressure is increased.
TEMPERATURE IS REDUCED
PRESSURE IS INCREASED
The role of a catalyst in a chemical reaction is to change the
A equilibrium constant
B activation energy
C final products
D heat of reaction
ACTIVATION ENERGY
The vessel dispersion number (D/μL) for plug flow is
A 0
B 500
C 750
D ∞
0
Molecularity of a reaction
A is always equal to the overall order of reaction.
B may not be equal to the order of reaction.
C can’t have a fractional value.
D both (b) and (c).
MAY NOT BE EQUAL TO THE ORDER OF REACTION
CAN’T HAVE A FRACTIONAL VALUE
BET apparatus is used to determine the
A specific surface of a porous catalyst.
B pore size distribution.
C pore diameter.
D porosity of the catalyst bed.
SPECIFIC SURFACE OF POROUS CATALYST
Carrier in a catalyst increases its
A surface area
B activity
C performance
D none of these
SURFACE AREA
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
A nD = (n+1)/2
B nD = n/2
C nD = n + 1
D none of these
nD = (n+1)/2
When the reaction occurs in the diffusion controlled region, the apparent activation energy as measured is only __________ the true value.
A twice
B half
C equal
D none of these
HALF
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.
A increase
B increase exponentially
C decrease
D remain unchanged
DECREASES
An elementary liquid phase decomposition reaction A -> K 2B is to be carried out in a CSTR. The design equation is
kt= Xa/(1-Xa)
Kinetics of a solid catalysed reaction can best be studied in a __________ reactor.
A batch
B plug-flow
C mixed
D none of these
MIXED
According to Arhenious equation of temperature dependency of rate constant for an elementary reaction
A k ∝ T
B k ∝ e-E/RT
C k ∝ T e-E/RT
D none of these
k ∝ e-E/RT
The reactions of high molecularity are rare, because
A of very large activation energy of many bodies.
B of low probability of many body collisions.
C many body collisions are not favoured energetically.
D of requirement of very large concentration for such reactions.
OF LOW PROBABILITY OF MANY BODY COLLISIONS
Which of the following is the most suitable for isothermal operation ?
A Batch reactor
B Back-mix reactor
C Plug-flow reactor
D Fixed bed reactor
BACK-MIX REACTOR
For a first order chemical reaction, the rate constant
A changes on changing the concentration units.
B is not a function of the unit of time.
C has unit of time-1.
D none ofthese.
HAS UNIT OF /TIME
Which of the following is an autocatalytic reaction ?
A Photochemical reactions
B Microbial fermentation reaction
C Enzyme fermentation reaction
D Ammonia synthesis reaction
MICROBIAL FERMENTATION REACTION
The performance of a cascade of CSTR’s can be improved by adding
A a P.F. reactor in series.
B a P.F. reactor in parallel.
C more CSTR’s in series.
D more CSTR’s in parallel.
MORE CSTR’S IN SERIES
A multiple reaction may be classified as a __________ reaction.
A consecutive or side
B parallel or side
C mixed
D all (a), (b) and (c)
CONSECUTIVE OR SIDE
PARALLEL OR SIDE
MIXED
Holding time for flow reactors is __________ the space time, for constant fluid density
A double
B triple
C equal to
D none of these.
EQUAL TO
Pick out the wrong statement.
A In a multistep reaction, the slowest step is the rate determining step.
B In general, the rate of a reaction becomes triple for every 10°C rise in temperature.
C Slow chemical reactions have generally high values of activation energy.
D Molecularity of a reaction can not be zero but the order of a reaction can be zero.
In general, the rate of a reaction becomes triple for every 10°C rise in temperature.
The order of the reaction, H2 + CL -> SUNLIGHT 2HCL, is
A 0
B 1
C 2
D 3
0
Arhenious equation shows the variation of __________ with temperature.
A reaction rate
B rate constant
C energy of activation
D frequency factor
RATE CONSTANT
Arhenious equation shows the variation of __________ with temperature.
A reaction rate
B rate constant
C energy of activation
D frequency factor
INCREASES
In which of the following reactions, the equilibrium will shift to the right, if the total pressure is increased?
A H2 + Cl2 <-> 2HCl
B N2 + O2 <->2NO
C N2O4 <-> 2 NO2
D H2 + I2 <-> 2HI
N2 + O2 <->2NO
The catalyst in a first order chemical reaction changes the
A equilibrium constant
B activation energy
C heat of formation of the product
D heat of reaction
ACTIVATION ENERGY
Oil is hydrogenated using nickel catalyst in a __________ reactor.
A batch
B slurry
C fluidised bed
D fixed bed
SLURRY
The performance equations for constant density systems are identical for
A P.F.R. and backmix reactor.
B P.F.R. and batch reactor.
C P.F.R, batch reactor and backmix reactor.
D batch reactor and backmix reactor.
PFR AND BATCH REACTOR
Reaction rate of a first order reaction, which is half completed in 23 minutes will be
A 0.03 sec-1
B 0.03 min-1
C 0.03 hr-1
D 0.05 min-1
0.03/MIN
Which of the following is the optimum operating condition for an exothermic reversible reaction taking place in a plug-flow reactor ?
A Temperature should be high in the beginning and decreased towards the end of the reaction.
B Very low temperature should be used throughout the reaction.
C Very high temperature should be used throughout the reaction.
D none of these.
TEMPERATURE SHOULD BE HIGH IN THE BEGINNING AND DECREASED TOWARDS THE END OF THE REACTION
The half life period ‘t’ of a zero order reaction, A -> K PRODUCTS, is equal to
A CA0/2K
B CA0/K
C 0.693/K
D 1/K
CA0/2K
In case of calcination of limestone, CaCO3 CaO + CO2, the addition of more of CaO will result in __________ in the concentration of CO2.
A no change
B increase
C decrease
D unpredictable from the data
NO CHANGE
The rate of a homogeneous reaction is a function of
A temperature and pressure only.
B temperature and composition only.
C pressure and composition only.
D all temperature, pressure and composition.
ALL TEMPERATURE, PRESSURE, AND COMPOSITION
In the fluid catalytic cracker (FCC), the cracking reaction is __________ (A) and the regeneration is___(B) __________
A (A) exothermic (B) endothermic
B (A) exothermic (B) exothermic
C (A) endothermic (B) enodthermic
D (A) endothermic (B) exothermic
(A) endothermic (B) exothermic
Pick out the correct statement.
A A catalyst does not change AH of the reaction.
B A catalyst changes the equilibrium point.
C Law of mass action was suggested by Le-Chatelier.
D The difference between the energy of reactants and that of the products is the activation energy.
A CATALYST DOES NOT CHANGE AH OF THE REACTION
Promoter is added to the catalyst to improve its
A porosity
B sensitivity
C surface area
D none of these
SENSITIVITY
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
A be more in CSTR than in PFR.
B be more in PFR than in CSTR.
C be same in both cases.
D depend on the temperature.
BE MORE IN PFR THAN IN CSTR
When a high liquid hold up is required in a reactor for gas liquid reaction, use __________ coloumn.
A packed
B spray
C tray
D bubble
BUBBLE
In an exothermic reaction, the energy of the reacting substances as compared to that of products is
A more
B less
C same
D either (a) or (b), depends on order of reaction.
MORE
For a tubular flow reactor with uniform concentration and temperature, the independent variable is
A time
B length
C diameter
D none of these
LENGTH
Pick out the wrong statement.
A For a first order consecutive reaction, a tubular flow reactor as compared to a stirred tank reactor provides higher overall selectivity.
B For an ideal mixed reactor at steady state, the exit stream has the same composition as fluid within the reactor and the space time is equivalent to holding time for constant density system.
C Plug flow reactor (PFR) is always smaller than mixed reactor for all positive reaction orders for a particular duty.
D Reaction rate does not decrease appreciably as the reaction proceeds in case of an autocatalytic reaction.
For a first order consecutive reaction, a tubular flow reactor as compared to a stirred tank reactor provides higher overall selectivity.
The first order gas phase reaction A -> K1 2B is conducted isothermally in batch mode. The rate of change of conversion with time is given by
dXa/dt = k1 (1-Xa)
The extent of a reaction is
A different for reactants and products.
B dimensionless.
C depends on the stoichiometric co-efficient.
D all of the above
DIFFERENT REACTANTS AND PRODUCTS
DIMENSIONLESS
DEPENDS ON THE STOICHIOMETRIC COEFFICIENT
Higher free energy of activation of a chemical reaction (at a given temperature) implies
A slower rate of reaction.
B higher rate of reaction.
C higher equilibrium conversion.
D both (b) and (c).
SLOWER RATE OF REACTION
Calcination reaction of limestone (CaCO3 CaO + CO2) goes to completion in the rotary kiln, because
A CaO is not dissociated.
B CO2 escapes continuously.
C of high calcination temperature.
D CaO is more stable than CaCO3.
CO2 ESCAPES CONTINUOUSLY
The reactions with low activation energy are
A always spantaneous
B slow
C fast
D non-spontaneous
FAST
Molecularity of an elementary reaction, P + Q -> R + S is
A 1
B 2
C 3
D 4
4
Which of the following is not endothermic in nature ?
A Combustion of sulphur.
B Gasification of carbon.
C Thermal cracking of fuel oil.
D Steam reforming of naphtha.
COMBUSTION OF SULFUR
CThe rate of an autocatalytic reaction, A + B -> K B +B , is given by -rA = k . CA . CB. In this case, the
A plot of - rA Vs CA is a straight line with slope k.
B plot of - rA Vs CA is a hyperbola.
C rate of disappearance of reactant A is maximum, where CA = CB
D both ‘b’ & ‘c’
plot of - rA Vs CA is a hyperbola.
rate of disappearance of reactant A is maximum, where CA = CB
The space time is equivalent to the holding time in a steady state mixed reactor for
A non-isothermal gas reaction.
B variable fluid density systems.
C constant fluid density systems.
D gas reactions with changing no. of moles.
CONSTANT FLUID DENSITY SYSTEMS
The dispersion number of perfect mixed flow is
A 0
B > 150
C ∞
D < 2100
∞
For the reaction 2X + Y -> K Z, 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 ?
A 0.4
B 0.1
C 0.2
D none ofthese
0.4
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.
A 190
B 290
C 390
D 490
290
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
A surface Kc/(1 + TS) reaction between absorbed A and B in the gas phase.
B surface reaction between absorbed A and absorbed B.
C surface reaction between A in the gas phase and absorbed B.
D desorption of C
DESORPTION OF C
Half life period of a first order irreversible reaction A B is
A k/2
B ln k/2
C ln 2/k
D ln 0.5/k
ln 2/k
Pick out the wrong statement.
A Autocatalytic reactions are exemplified by microbial fermentation reactions.
B The slowest step has the greatest influence on the overall reaction rate in case of an irreversible series reaction.
C The fractional conversion at any time is same for both the constant as well as the variable volume system in case of an irreversible unimolecular type first order reaction.
D Hydrolysis of ester in presence of alkali or acid is a zero order reaction.
HYDROLYSIS OF ESTER IN PRESENCE OF ALKALI OR ACID IS A ZERO ORDER 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.)
A Reactor dispersion number (D/vL)
B Reduced time
C Thiele modulus
D None of these
NONE OF THESE
Pick out the wrong statement
A For the same conversion, the holding time required in a batch reactor, is always equal to the space time required in a PFR.
B Two mixed reactors of unequal size are available for producing a specified product, formed by a homogenous second order reaction. To achieve maximum production rate, the smaller reactor should be placed in series before the larger reactor.
C Arrehenius equation describing the effect of temperature on rate constant is given by, K = A.e-Ea/RT
D 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.
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.
The energy of activation of a chemical reaction
A is same as heat of reaction at constant pressure.
B is the minimum energy which the molecules must have before the reaction can take place.
C varies as fifth power of the temperature.
D both (b) and (c).
IS THE MINIMUM ENERGY WHICH THE MOLECULES MUST HAVE BEFORE THE REACTION CAN TAKE PLACE
Chemical kinetics can predict the __________ of a chemical reaction.
A rate
B feasibility
C both (a) & (b)
D neither (a) nor (b)
RATE
Which of the following fixes the volume of a batch reactor for a particular conversion and production rate ?
A Operating conditions (e.g. pressure and temperature)
B Rate constant
C Density of mixture
D None of these
DENSITY OF MIXTURE
Volume change for unimolecular type first order reaction A -> K 4R, increases __________ with time.
A linearly
B exponentially
C parabolically
D logarithmically
EXPONENTIALLY
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.
A 18
B 24
C 6
D 12
24
Decomposition rate of a liquid ‘X’ which decomposes as per the reaction X -> K1 A, X-> K2 B, X -> K3 C is given by
A K1 . CX
B (K1 + K2 + K3)CX
C (K1 + K2)CX
D (K2 + K3)CX
(K1 + K2)CX
With increase in the space time of an irreversible isothermal reaction being carried out in a P.F. reactor, the conversion will
A increase
B decrease
C remain same
D data in insufficient; can’t be predicted
INCREASE
A catalyst promoter
A improves the activity of a catalyst.
B acts as a catalyst support.
C itself has very high activity.
D all (a), (b) and (c).
IMPROVES THE ACTIVITY OF A CATALYST
In case of a P.F.R., there
A may be lateral mixing of fluid.
B should not be any mixing along C the flow path.
C both (a) and (b).
D neither (a) nor (b).
MAY BE LATERAL MIXING OF FLUID
SHOULD NOT BE ANY MIXING ALONG THE FLOW PATH
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.
A film diffusion
B diffusion through ash layer
C chemical reaction
D either (a), (b) or (c)
DIFFUSION THROUGH ASH LAYER
If ΔG (free energy change) for a chemical reaction is very large and negative, then the reaction is
A not feasible.
B just feasible.
C very much feasible.
D unpredictable as ΔG is no measure of feasibility of a reaction.
VERY MUCH FEASIBLE
In a zero order reaction, reactants concentration does not change with time and the
A time for half change is half the time taken for completion of the reaction.
B time for half change is independent of the initial concentration.
C time for completion of the reaction is independent of the initial concentration.
D reaction rate is trebled when the initial concentration is trebled.
TIME FOR HALF CHANGE IS HALF THE TIME TAKEN FOR COMPLETION OF THE REACTION
The minimum energy required to allow a chemical reaction to proceed is termed as the ‘threshold energy ‘. Chemical reaction with low activation energy are
A always irreversible.
B insensitive to temperature changes.
C mostly irreversible.
D highly temperature sensitive.
INSENSITIVE TO TEMPERATURE CHANGES
If Thiele modulus is __________ , then the pore diffusion resistance in a catalyst may be considered as negligible.
A 0
B ∞
C < 0.5
D > 0.5
<0.5
From collison theory, the reaction rate constant is proportional to
T^m* exp(-E/RT)
For a mixed flow reactor operating at steady state, the rate of reaction is given by
Fao/V * Xa
Catalytic action in a catalytic chemical reaction follows from the ability of catalyst to change the
A activation energy
B equilibrium constant
C heat of reaction
D none of these
ACTIVATION ENERGY
In Langmuir treatment of adsorption,
A whole surface of the catalyst does not have the same activity for adsorption and there is attraction between the adsorbed molecule.
B whole surface of the catalyst is essentially uniform and the adsorbed molecule has no effect on the rate of adsorption per site.
C all the adsorption does not take place by the same mechanism.
D extent of adsorption is more than one complete monomolecular layer on the surface.
whole surface of the catalyst is essentially uniform and the adsorbed molecule has no effect on the rate of adsorption per site.
Organic catalysts differ from the inorganic catalyst in the sense that the former is
A active at cryogenic temperatures only.
B prohibitively costly.
C proteinous in nature.
D active at very high temperature only.
PROTEINOUS IN NATURE
An endothermic aqueous phase first order irreversible reaction is carried out in an adiabatic plug flow reactor. The rate of reaction
A is maximum at the inlet of the reactor.
B goes through a maximum along the length of the reactor.
C goes through a minimum along the length of the reactor.
D is maximum at the exit of the reactor.
IS MAXIMUM AT THE INLET OF THE REACTOR
For an ideal plug flow reactor, the value of Peclet number is
A 0
B ∞
C 1
D 10
0
An endothermic second order reaction is carried out in an adiabatic plug flow reactor. The rate of heat generation is
A maximum at the inlet of the reactor.
B maximum at the exit of the reactor.
C maximum at the centre of the reactor.
D constant throughout the reactor.
MAXIMUM AT THE INLET OF THE REACTOR
Equilibrium of a chemical reaction as viewed by kinetics is a __________ state.
A dynamic steady
B static steady
C dynamic unsteady
D none of these
DYNAMIC STEADY
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.
A 0.5
B 1
C 2
D 3
0.5
The size of plug flow reactor (PFR) for all positive reaction orders and for any given duty, is __________ that of mixed reactor.
A greater than
B equal to
C smaller than
D unpredictable from the data
SMALLER THAN
A space time of 3 hours for a flow reactor means that
A the time required to process one reactor volume of feed (measured at specified conditions) is 3 hours.
B three reactor volumes of feed can be processed every hour.
C it takes three hours to dump the entire volume of the reactor with feed.
D conversion is cent per cent after three hours.
the time required to process one reactor volume of feed (measured at specified conditions) is 3 hours.
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
A 1
B 2
C 3
D 0
3
The experimentally determined overall order of 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 molecularity of 2.
D reaction is elementary but the molecularity may not be 2.
REACTION IS ELEMENTARY WITH MOLECULARITY OF 2
In a continuous flow stirred tank reactor, the composition of the exit stream
A is same as that in the reactor.
B is different than that in the reactor.
C depends upon the flow rate of inlet stream.
D none of these.
IS SAME AS THAT IN THE REACTOR
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.
A decrease
B increase
C no change
D either (a) or (b), depends on the type of reaction
NO CHANGE
The energy balance equation over a tubular reactor under transient conditions is
A an ordinary non-linear differential equation.
B an algebric differential equation.
C a linear partial differential equation.
D a non-linear partial differential equation.
A LINEAR PARTIAL DIFFERENTIAL EQUATION
Which of the following factors control the deactivation of a porous catalyst pellet ?
A Decay reactions.
B Pore diffusion.
C Form of surface attack by poison.
D All (a), (b) and (c)
DECAY REACTIONS
PORE DIFFUSION
FORM OF SURFACE ATTACK BY POISON
For the reaction, A + B -> 2B + C,
A rA = rB
B rA = -rB
C rA = 2rB
D rA = rB/2
rA = -rB
Transition state theory gives the rate constant as
A K α e-E/RT
B K α eE/RT
C K α T . e-E/RT
D K α T. e-E/RT
K α T . e-E/RT
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 followed by a PFR.
Pick out the wrong statement.
A Use of different catalysts in a reversible catalytic chemical reaction does not change the equilibrium composition.
B Alumina is added as a promoter to iron catalyst in ammonia synthesis reaction.
C Activation energy for a reaction is obtained from the intercept of the Ar-rhenious plot.
D Presence of inerts affects the equilibrium conversion of reactants in a chemical reaction.
Activation energy for a reaction is obtained from the intercept of the Ar-rhenious plot.
In a reversible reaction, a catalyst increases the rate of forward reaction
A only.
B to a greater extent than that of the backward reaction.
C and decreases that of the backward reaction.
D and the backward reaction equally.
AND THE BACKWARD REACTION EQUALLY
Maximum equilibrium conversion for endothermic reaction is obtained at the __________ temperature.
A highest possible
B lowest possible
C intermediate
D room
HIGHEST POSSIBLE
When an exothermic reversible reaction is conducted adiabatically, the rate of reaction
A continuously increases.
B continuously decreases.
C passes through a maximum.
D passes through a minimum.
PASSES THROUGH A MAXIMUM
For a first order chemical reaction in a porous catalyst, the Thiele modulus is 10. The effectiveness factor is approximately equal to
A 1
B 0.5
C 0.1
D 0
0.1
The rate equation for the reaction represented by, X -> Y 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
A zero order & K1/K2
B zero order & K1
C first order & K1
D first order & K1/K2
zero order & K1/K2
In solid catalysed reactions the diffusional effects are more likely to affect the overall rate of reaction for
A fast reactions in catalyst of small pore diameter.
B fast reaction in catalyst of large pore diameter.
C slow reactions in catalyst of small pore diameter.
D slow reactions in catalyst of large pore diameter.
SLOW REACTIONS IN CATALYST OF SMALL PORE DIAMETER
Helium-mercury method can be used to determine the __________ of the catalyst particle.
A pore volume
B solid density
C porosity
D all (a), (b), & (c).
PORE VOLUME, SOLID DENSITY, POROSITY
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’ ?
A 4
B 1/4
C 16
D 2
4
Chemical reaction rate of a component depends upon the
A composition of the component only.
B temperature of the system.
C pressure of the system.
D all (a), (b) and (c).
COMPOSITION, TEMPERATURE, PRESSURE
In a semi-batch reactor
A velocity of reaction can be controlled.
B maximum conversion can be controlled.
C both the reactants flow counter-currently.
D residence time is constant.
VELOCITY OF REACTION CAN BE CONTROLLED
A trickle bed reactor is the one, which
A has altogether three streams either entering or leaving.
B processes three reactants at different flow rates.
C processes three reactants with same flow rate.
D employs all the three phases (i.e.. .solid, liquid and gas).
EMPLOYS ALL THREE PHASES
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 ?
A 0
B 1
C 2
D 3
0
The excess energy of the reactants required to dissociate into products is known as the __________ energy.
A thermal
B activation
C threshold
D binding
ACTIVATION ENERGY
In a/an __________ vessel, the fluid enters and leaves following plug flow.
A open
B closed
C open-closed
D close-opened
CLOSED
Shift conversion reaction
A converts N2 and H2 into NH3.
B converts CO to CO2 with steam.
C is non-catalytic.
D is highly exothermic.
converts CO to CO2 with steam.
The importance of diffusion in a catalyst are increased by
A large catalyst particle size.
B an active surface of the catalyst.
C small pore diameter.
D all (a), (b) and (c).
ALL A B C
A back mix reactor is
A suitable for gas phase reactions.
B ideal at very low conversion.
C same as plug flow reactor (PFR).
D same as ideal stirred tank reactor.
SAME AS IDEAL STIRRED TANK REACTOR
Which one is the rate controlling step in a solid-gas non-catalytic reaction occurring at very high temperature?
A Pore diffusion
B Film diffusion
C Ash layer diffusion
D Chemical reaction
FILM DIFFUSION
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
A absorption of A.
B surface reaction between absorbed A and absorbed B.
C surface reaction between absorbed A and B in the gas phase.
D surface reaction between A in the gas phase and absorbed B.
SURFACE REACTION BETWEEN ABSORBED A AND B IN THE GAS PHASE
For a __________ order chemical reaction,A -> K , the half life period is independent of the initial concentration of the reactant A.
A zero
B first
C second
D third
FIRST
The ratio of moles of a reactant converted into the desired product to that converted into unwanted product is called
A operational yield
B relative yield
C selectivity
D none of these
SELECTIVITY
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
A m
B 1/m
C SQRT (m)
D m2
1/m
The eddy diffusivity for a liquid in plug flow must be
A 1
B 0
C ∞
D between 0 and 1
0
For multiple reactions, the flow pattern within the vessel affects the
A size requirement
B distribution of reaction products
C both (a) and (b)
D neither (a) nor (b)
SIZE REQUIREMENT AND DISTRIBUTION OF REACTION PRODUCTS
The rate expression for the gaseous phase reaction, CO + 2H2 CH3OH, is given by, . Which of the following is not possible ?
α = 1, β = 1, γ =1
α = 1, β = 2, γ = 1
α = 1/3, β = 2/3, γ = 1/3
α = 1/2, β = 1, γ = 1/2
α = 1, β = 1, γ =1
For the same residence time, which one will give the maximum conversion ?
A Single stirred tank (v = 5 litres).
B Two stirred tank (each of 2.5 litres) in series.
C Stirred tank followed by tubular flow reactor (each of 2.5 litres).
D 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.
A N2
B H2
C CO2
D He
N2
The exit age distribution curve E(t) for an ideal CSTR with the average residence time, τ, is given by
e-t/τ
(e^-t/τ)/T
1 - e-t/τ
(e^-t/τ)/T
The rate constant of a reaction depends on the
A initial concentration of reactants.
B time of reaction.
C temperature of the system.
D 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 ?
A 0.253
B 0.338
C 0.152
D 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
A CSTR of volume V
B PFR of volume V
C CSTR of volume V/X
D 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.
A 3
B 4
C 6
D 8
4
For a __________ order reaction, the units of rate constant and rate of reaction are the same.
A zero
B first
C second
D fractional
ZERO
In case of staged packed bed reactors carrying out exothermic reaction, use
A high recycle for pure gas.
B plug flow for dilute liquid requiring no large preheating of feed.
C cold shot operations for a dilute solution requiring large preheating to bring the stream upto the reaction temperature.
D all (a), (b) and (c).
ALL A B C
Vegetable oils are hydrogenated in a __________ reactor.
A slurry
B plug flow
C homogeneous catalytic
D none of these
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
A 1/2
B 1/3
C 1/4
D 1/5
1/3
The rate of reaction does not decrease appreciably as the reaction proceeds in case of __________ reactions.
A autocatalytic
B exothermic
C endothermic
D autothermal
AUTOCATALYTIC
For all positive reaction orders for a particular duty,
A mixed reactor is always larger than the plug-flow reactor.
B ratio of the volume of the mixed reactor to that of the plug-flow reactor decreases with order.
C reactor size is independent of the type of flow.
D density variation during reaction affects design.
MIXED REACTOR IS ALWAYS LARGER THAN THE PLUG-FLOW REACTOR
The heat of reaction
A depends on the pressure only.
B depends on the mechanism of reaction only.
C depends on both pressure and mechanism of reaction.
D 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 ?
A Pressure
B Temperature
C Concentration and catalyst
D None of these.
CONCENTRATION AND CATALYST
With increase in temperature, the equilibrium conversion of a reversible exothermic reaction
A decreases
B increases
C remains unaffected
D decreases linearily with temperature
DECREASES
In a CSTR __________ varies with time.
A reaction rate
B concentration
C both (a) & (b)
D neither (a) nor (b)
NEITHER
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.) ?
A 1/3
B 1/2
C 2/3
D 2
2/3
As the chemical reaction proceeds, the rate of reaction
A increases.
B decreases.
C remains same.
D may increase or decrease depending on the type of reaction.
DECREASE
Pick out the wrong statement.
A A catalyst does not alter the final position of equilibrium in a reversible reaction.
B A catalyst initiates a reaction.
C A catalyst is specific in reaction.
D 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.
A more than
B less than
C same as
D data insufficient; can’t be predicted.
SAME AS
Photo-chemical reactions occur in presence of
A sunlight.
B darkness,
C solid catalysts.
D 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
A V/n
B V
C V.n
D 1/V
V
Knudsen diffusion is directly proportional to
T
SQRT (T)
1/T
T2
SQRT (T)
Fractional conversion __________ for an exothermic reversible chemical reaction, when the temperature is maximum.
A increases
B remains unchanged
C decreases
D unpredictable from the data
DECREASES
Non-catalytic fluid-solid reactions are represented by __________ model.
A continuous reaction
B unreacted core
C both (a) and (b)
D neither (a) and (b)
CONTINUOUS REACTION AND UNREACTED CORE
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
A 2τ
B 0.5τ
C τ/0.693
D 0.693τ
2τ
On application of pressure to the equilibrium system, ice <-> water ; which of the following phenomenon will occur ?
A Water will evaporate
B Equilibrium will not be attained
C More ice will be formed
D More water will be formed.
MORE WATER WILL BE FORMED
Participation of __________ is involved in the occurrence of a chemical reaction.
A protons
B neutrons
C electrons
D none of these
ELECTRONS
Promoter.
A initiates a chemical reaction and is a catalyst by itself.
B atlers the position of equilibrium in a reversible reaction.
C increases the number of active centres by increasing the unevenness of catalyst surface and by creating discontinuities in the crystals.
D all (a), (b) and (c).
increases the number of active centres by increasing the unevenness of catalyst surface and by creating discontinuities in the crystals.
The rate constant of a reaction is a function of the
A time of reaction.
B temperature of the system.
C extent of reaction.
D initial concentration of the reactants.
TEMPERATURE OF THE SYSTEM
Mean residence time is equal to the space time, when
A the feed rate is measured at temperature and pressure in the reactor.
B the temperature, pressure and the density of reaction mixture remains constant throughout the reactor.
C there is no change in number of moles in gaseous reaction.
D all (a), (b) and (c).
ALL A B C
If ‘n’ is the order of reaction, then unit of rate constant is
A 1/(time)(concentration)n - 1
B (time)-1 (concentration)n - 1
C (time)n - 1 (concentration)
D none of these
1/(time)(concentration)n - 1
Batch process is preferred over continuous process, when the
A product yields and quality can not be achieved in continuous process, because of long residence time.
B sales demand of product is not steady.
C same equipment can not be used for several processes of the same nature.
D all (a), (b) & (c)
ALL A B C
.
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.
A 0
B 1
C 2
D 3
3
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
A higher in P.F. reactor
B higher in CSTR
C same in both the reactors
D data insufficient; can’t be predicted
HIGHER IN PFR
For any reaction, we may write conversion as a function of
A time
B temperature
C concentration
D all (a), (b) & (c)
TIME, TEMPERATURE, CONCENTRATION
The use of space time is preferred over the mean residence time in the design of a/an
A batch reactor
B ideal tubular-flow reactor
C slurry reactor
D CSTR
IDEAL TUBULAR-FLOW REACTOR
Autocatalytic reactions are best carried out in a
A CSTR
B CSTR in series
C plug flow reactor
D recycle reactor
RECYCLE REACTOR
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 2/3
B 5/8
C 1/3
D 3/8
5/8
A batch reactor suffers from following disadvantage.
A Poor product quality control.
B High labour and handling cost.
C High shutdown time requirement for emptying, cleaning and refilling.
D All (a), (b)and(c).
ALL A B C
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
A equal in size.
B of different sizes.
C of such size that the ratio of their volumes is < 5.
D none of these.
EQUAL IN SIZE
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
d(Vca)/dt = F * CAF - k Ca^2V
Half life period of a chemical reaction is proportional to CA0-1 , if the reaction is of __________ order.
A first
B zero
C second
D third
SECOND
The irreversible reaction, X <-> Y, is the special case of the reversible reaction, X Y, in which the
A equilibrium constant is infinite.
B fractional conversion of ‘A’ at equilibrium is unity.
C concentration of ‘A’ at equilibrium is zero.
D all (a), (b) and (c).
ALL A B C
The equilibrium constant K of a chemical reaction depends on
A temperature only.
B pressure only.
C temperature and pressure.
D ratio of reactants.
TEMPERATURE ONLY
The reaction rate almost gets doubled for 10°C rise in temperature. This is due to the fact that the
A increased temperature reduces the activation energy.
B fraction of molecules having threshold energy increases.
C collision frequency increases.
D value of threshold energy decreases.
FRACTION OF MOLECULE HAVING THRESHOLD ENERGY INCREASES
Which of the following is not a unit of reaction rate ?
A Moles for med/(surface of catalyst) (time)
B Moles formed/volume of reactor) (time)
C Mole formed/volume of catalyst)
(time)
D None of these
NONE OF THESE
.
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 ?
A Langmuir’s assumption applies to every adsorbed layer.
B There is no dynamic equilibrium between successive layer.
C The 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.
D none of these.
THERE IS NO DYNAMIC EQUILLIBRIUM BETWEEN SUCCESSIVE LAYER
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
A 15, 10, 5
B 5, 10, 15
C 10, 5, 15
D 10, 15, 5
15,10,5
The following half life data are available for the irreversible liquid phase reaction A products.
INITIAL CONCENTRATION 2, 8
HALF-LIFE 2, 1
The overall order of reaction is
A 0.5
B 1
C 1.5
D 2
1.5
A non-catalytic chemical reaction of the type is called a __________ reaction.
parallel
series
series-parallel
none of these
SERIES-PARALLEL
The unit of frequency factor in Arhenious equation is
A same as that of rate constant.
B same as that of activation energy.
C dimensionless.
D none of these.
SAME AS THAT OF RATE CONSTANT
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)
A increases
B decreases
C remains same
D increases linearly
INCREASES
Reaction of benzene with chlorine gas to produce tri-chlorobenzene exemplifies a/an __________ reaction.
A elementary
B parallel
C consecutive
D none of these
CONSECUTIVE
For the gaseous reaction 2A B, where the feed consists of 50 mole % A and 50 mole % inerts, the expansion factor is
A 1
B -0.5
C -0.25
D 0
-0.25
The molecularity and the order of reaction respectively, for the hydrolysis of methyl acetate in presence of acids are
A 2 & 1
B 11 & 2
C 2 && 2
D 1 & 1
2 & 1
The irreversible reaction is a special case of reversible reaction, if the
A equilibrium constant is 1.
B conversion of the reactant at equilibrium condition is zero.
C reactant concentration at equilibrium condition is zero.
D all (a), (b) and (c).
REACTANT CONCENTRATION AT EQUILIBRIUM CONDITION IS ZERO
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
A 7
B 6
C 3
D 7/3
7
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
A low temperature in a CSTR.
B high temperature in a CSTR.
C low temperature in a PFR.
D high temperature in a PFR.
HIGH TEMPERATURE IN A PFR
In an ideal mixed reactor (at steady state), the
A space time is equivalent to holding time for constant density systems.
B composition throughout the reactor remains same.
C exit stream has the same composition as the fluid within the reactor.
D all (a), (b) and (c).
ALL A B C
The knowledge of initial concentration and rate constant is necessary to determine the half life time of a reaction of __________ order.
A zero
B first
C second
D none of these
SECOND
In an ideal mixed reactor (at steady state), the
A space time is equivalent to holding time for constant density systems.
B composition throughout the reactor remains same.
C exit stream has the same composition as the fluid within the reactor.
D all (a), (b) and (c).
ALL A B C
A Catalyst
A increases the equilibrium concentration of the product.
B changes the equilibrium constant of the reaction.
C shortens the time to reach the equilibrium.
D none of these.
SHORTENS THE TIME TO REACH EQUILIBRIUM
The reaction rate constants at two different temperature T1 and T2 are related by
ln (k2/k1) = E/R ( 1/T1 - 1/T2)
The synthesis of proteins and metabolism in biological objects occur in the presence of biocatalyst called
A ferment or an enzyme
B haemoglobin
C fungi
D none of these
FUNGI
Pick out the wrong statement.
A A particular chemical reaction is more temperature sensitive at low temperatures.
B A very high value of equilibrium constant, K (K»_space; 1) indicates that the reaction is practically irreversible in nature.
C The intercept of the Arrhenious plot is called the ‘activation energy’.
D Non-ideal flow takes place in reactors due to recycling, channeling or by creation of stagnant regions.
The intercept of the Arrhenious plot is called the ‘activation energy’.
Kinetics of a catalytic reaction can be best studied on a/an __________ reactor.
A mixed
B integral (plug flow)
C differential (flow)
D either (a), (b) and (c).
EITHER A B C
In case of a __________ reactor, the composition in the reactor and at the exit of the reactor is the same.
A semi-batch
B tubular
C batch
D back-mix
BACK-MIX
Exothermic reactions are best carried out in
A a CSTR.
B CSTR in series.
C a plug flow reactor followed by CSTR.
D CSTR followed by a plug flow reactor.
CSTR FOLLOWED BY A PFR
What is the order of chemical reaction A + B +C -> K D, if it is found that the reaction rate doubles on doubling the concentration of B and also the reaction rate doubles when the concentrations of both A & B were doubled and quandrupled when the concentrations of both B & C were doubled ?
A 1
B 2
C 3
D 4
2
Reactions with high activation energy are
A very temperature sensitive
B temperature insensitive
C always irreversible
D always reversible
VERY TEMPERATURE SENSITIVE
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/ an-1
In case of a/an __________ chemical reaction, conversion increases with the rise in temperature.
A reversible exothermic
B irreversible exothermic
C irreversible endothermic
D reversible endothermic
REVERSIBLE ENDOTHERMIC
A space velocity of 5 hr-1 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.
five reactor volumes of feed (at specified conditions) are being fed into the reactor per hour.
With increase in initial concentration, the fractional conversion of a first order reaction in a given time
A increases
B decreases
C remains constant
D unpredictable
REMAINS CONSTANT
The rate of reaction of a/an __________ reaction is not affected by temperature rise.
A autocatalytic
B photochemical
C consecutive
D zero order.
PHOTOCHEMICAL
With an increase in pressure in gaseous phase chemical reactions, the fractional conversion __________ when the number of moles decreases.
A increases
B decreases
C remains unaffected
D unpredictable from the data
INCREASES
Half-life period for a first order reaction is __________ the initial concentration of the reactant.
A directly proportional to
B inversely proportional to
C independent of
D none of these
INDEPENDENT OF
Carbon particles accummulated on the catalyst used in the gas oil cracking lies in the category of __________ poison.
A deposited
B chemisorbed
C selectivity
D stability
DEPOSITED
The order of the chemical reaction, 2A + B -> K C, whose rate equation is given as -rA= KCA2. CB is
A 0
B 1
C 2
D 3
3
What is the dispersion number for a plug flow reactor ?
A 0
B ∞
C 1
D -1
0
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.
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.
AT LOW P AND LOW T
The catalytic converter for conversion of SO2 to SO3 by contact process should have a feed with SO2 content between
A 2-5%
B 7-10%
C 12-15%
D 20-25%
7-10%
If the pore diffusion controls in a catalytic reaction, the apparent activation energy Ea is equal to
A the intrinsic activation energy E.
B (E + ED) where ED is activation due to diffusion.
C (E + ED)/2
D ED/2
ED/2
With increase in K2/K1 in case of a unimolecular type elementary reactions, A -> K1 R -> K2 S the fractional yield of ‘R’ in mixed reactor (for a given conversion of ‘A’)
A decreases
B increases
C increases linearly
D remains same
DECREASES
Collision theory gives the rate constant for bimolecular reaction as
A K α SQRT T.e-E/RT
B K α eE/RT
C K α e-E/RT
D none of these
K α e-E/RT
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
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.
A 1
B 3
C 1/3
D 32
3
The temperature dependence of reaction rate constant (K) by Arhenius law is given by
K α e-E/RT
K α eE/RT
K α T . e-E/RT
K α T . SQRT e-E/RT
K α e-E/RT
For a __________ order chemical reaction, A+B -> K C , the fractional conversion of reactant ‘A’ is proportional to time.
A zero
B first
C second
D third
ZERO
Velocity of a chemical reaction
A decreases with increase in temperature.
B increases with increase of pressure of reactants for all reactions.
C decreases with increase of reactant concentration.
D none of these.
NONE OF THESE
Backmixing is most predominant in
A a well stirred batch reactor.
B a plug-flow reactor.
C a single CSTR.
D CSTR’s connected in series.
A SINGLE CSTR
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)
A decreases
B increases
C remains unaltered
D changes unpredictably.
DECREASES
Fluidised bed reactor is characterised by
A uniformity of temperature.
B comparatively smaller equipment.
C very small pressure drop.
D absence of continuous catalyst regeneration facility.
UNIFORMITY OF TEMPERATURE
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
PCl3 + Cl2 <-> PCl5
N + 3H2 <-> 2NH3
2SO2 + O2 <-> 2SO3
N2 + O2 <-> 2NO
Space time equals the mean residence time
A when the density of the reaction mixture is constant.
B for large diameter tubular reactor.
C for narrow diameter tubular reactor.
D for CSTR.
WHEN THE DENSITY OF THE REACTION MIXTURE IS CONSTANT
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.
A 4
B 8
C 12
D 16
16
Rate constant ‘k’ and absolute temperature ‘T’ are related by collision theory (for bimolecular) as
A k ∝ T1.5
B k ∝ exp(-E/RT)
C k ∝ SQRT T
D k ∝ T
k ∝ SQRT T
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
A 60
B 75
C 90
D 100
75
What is the dispersion number for a CSTR?
A 0
B 1
C < 1
D ∞
∞
Rate of a chemical reaction is independent of the concentration of the reactants for a __________ reaction.
A zero order
B third order
C consecutive
D none of these
ZERO ORDER
With increase in temperature, the rate constant obeying Arhenious equation
A increases.
B decreases.
C decreases exponentially.
D can either increase or decrease ; depends on the frequency factor.
INCREASES
Bulk diffusion in catalyst pore __________ with increase in pressure.
A increases
B decreases
C remains unchanged
D increases exponentially
DECREASES
Pick out the correct statement.
A A chemical reaction accompanied by absorption of heat is called an exothermic reaction.
B A chemical reaction accompanied by evolution of heat is called an endother-mic reaction.
C The rate constant for a first order reaction does not change on changing the concentration units.
D Chemical equilibrium state is dynamic in nature.
THE RATE CONSTANT FOR A FIRST ORDER REACTION DOES NOT CHANGE ON CHANGING THE CONCENTRATION UNITS
The concentration of A in a first order reaction, A -> B, decreases
A linearly with time.
B exponentially with time.
C very abruptly towards the end of the reaction.
D logarithmically with time.
EXPONENTIALLY WITH TIME
The equilibrium constant of chemical reaction __________ in the presence of catalyst.
A increases
B decreases
C remains unaffected
D can either increase or decrease (depends on the type of catalyst)
REMAINS UNAFFECTED
The order of a chemical reaction is
A an experimentally determined quantity.
B always equal to the total stoichiometric number of reactants.
C never fractional.
D none of these.
AN EXPERIMENTALLY DETERMINED QUANTITY
A chemical reaction occurs, when the energy of the reacting molecules is __________ the activation energy of reaction.\
A less than
B equal to
C more than
D equal to or more than
EQUAL OR MORE THAN
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
A 0.16
B 0.144
C 0.152
D 0.136
0.144
Catalyst is a substance, which __________ chemical reaction.
A increases the speed of a
B decreases the speed of a
C can either increase or decrease the speed of a
D alters the value of equilibrium constant in a reversible
CAN EITHER INCREASE OR DECREASE THE SPEED OF A
The residence time distribution of an ideal CSTR is
A 1/τ exp (-t/τ)
B τ exp (-t/τ)
C exp(-t/τ)
D 1/τ (-t/τ)
exp(-t/τ)
A rise in temperature
A normally tends to increase the reaction rate.
B does not affect a catalysed reaction.
C does not affect photo-chemical reaction rates.
D all (a), (b) and (c).
ALL A B C
The enzyme which can catalyse the conversion of glucose to ethyl alcohol is
A invertase
B maltase
C diastase
D zymase
ZYMASE
For reaction, P + 2 -> 3R, molar rate of consumption of P is
A double of that of Q.
B same as that of Q.
C half of that of Q.
D 2/3rd of that of Q.
HALF OF THAT OF Q
If pore diffusion is the controlling step in a solid catalysed reaction, the catalyst
A porosity is very important.
B porosity is of less importance.
C internal surface area is utilised efficiently.
D none of these.
POROSITY IS OF LESS IMPORTANT
The conversion of a reactant, undergoing a first order reaction, at a time equal to three times the half life of the reaction is
A 0.875
B 0.5
C 0.425
D data insufficient to calculate
0.875
In case of unimolecular type elementary reaction, A -> K1 B -> K2 C , plug flow reactor as compared to mixed reactor is
A more
B same
C less
D unpredictable
MORE
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 ?
A 1/2
B 1/3
C 1/9
D 3
1/2
The first order series reaction A -> K1 B -> K2 C 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
A k2 CB0 > k1 CA0
B k CA0 > k2.CB0
C CB0 > CA0
D CA0 > CB0
k2 CB0 > k1 CA0
A second order reaction of the form A + B -> C is called a pseudo-first order reaction, when
A CA0 = CB0
B CA0 > CB0
C CB0 > CA0
D CB0 ≥ CB0
CB0 ≥ CB0
Pick out the wrong statement.
A In a first order reaction, A products; the reaction becomes slower as it proceeds, because the concentration of A decreases and the rate is proportional to the concentration of A.
B Transition state theory approaches the problem of calculating reaction rates by concentrating on the idea of activated complexes.
C According to the penetration theory, the mass transfer co-efficient decreases, if the exposure time of an eddy to the solute decreases.
D If the rate of an irreversible reaction, A + B 2C is k.CA.CB, then the reaction is always elementary.
According to the penetration theory, the mass transfer co-efficient decreases, if the exposure time of an eddy to the solute decreases.
Effectiveness factor (E) of a catalyst pellet is defined as, E = (actual rate within pore of the catalyst)/ (rate if not snowed by pore diffusion) Effectiveness factor for a first order reaction is given by (where, T = Thiele modulus)
A tan hT/T
B tan T/T
C tan hT/tan T
D none of these
tan hT/T
Inversion of cane sugar is an example of
A unimolecular reaction with first order.
B bimolecular reaction with second order.
C bimolecular reaction with first order.
D unimolecular reaction with second order.
BIMOLECULAR REACTION WITH FIRST ORDER
Pick out the correct statement.
A A catalyst speeds up the forward reaction but slows shown the reverse reaction.
B Addition of catalyst changes the equilibrium constant.
C Pressure changes do not change the equilibrium concentrations.
D The composition of equilibrium is changed by catalyst.
Pressure changes do not change the equilibrium concentrations.
In which of the following gaseous phase reactions, the equilibrium of the reaction remains unaffacted by pressure changes ?
A 2O3 <-> 3O2
B N2 + O2 <-> 2NO
C 2NO2 <-> N2O4
D 2SO2 + O2 <-> 2SO3
N2 + O2 <-> 2NO
The mean conversion in the exit stream, for a second order, liquid phase reaction in a non-ideal flow reactor is given by
K2 CAO T / 1 + K2 CAO T
Integral method for analysing the kinetic data is used
A when the data are scattered.
Bfor testing specific mechanisms with simple rate expressions.
C both (a) and (b).
D none of these.
when the data are scattered.
for testing specific mechanisms with simple rate expressions.
Concentration of the limiting reactant (with initial concentration of a moles/litre) after time t is (a-x). Then ‘t’ for a first order reaction is given by
k t = ln a/(a-x)
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.
A 4
B 16
C 8
D 2
16
Rate of a chemical reaction is not affected by the
A catalyst.
B temperature.
C reactant’s concentration.
D number of molecules of reactants taking part in the reaction.
NUMBER OF MOLECULES OF REACTANTS TAKING PART IN THE REACTION
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.
A proportional to
B independent of
C inversely proportional to
D proportional to the square of
PROPORTIONAL TO
__________ resistance is not involved in the combustion of a carbon particle.
A Gas film
B Ash
C Chemical reaction
D none of these
ASH
In an ideal P.F.R. at steady state conditions
A the composition of reactants remains constant along a flow path.
B the conversion of the reactant varies from point to point along a flow path.
C there is no lateral mixing of fluid.
D there may be diffusion along the flow path.
THE CONVERSION OF THE REACTANT VARIES FROM POINT TO POINT ALONG A FLOW PATH
B.E.T. method of finding out surface area of a catalyst, uses the extension of __________ isotherm.
A Langmuir
B Freundlich
C Tempkin
D none of these
LANGMUIR
In a chemical reaction, repesented by, A -> K B, 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)
A CA
B CA2
C CA3
D CA4
CA2
Which of the following holds good for an elementary reaction, X + 27 -> K1 3Z?
A The rate of disappearance of ‘Y’ is equal to the rate of appearance of ‘Z’.
B The rate of disappearance of ‘Y’ is equal to the rate of disappearance of ‘X’.
C Three times the rate of disappearance of ‘X’ is equal to the rate of appearance of ‘Z’.
D The rate of disappearance of ‘X’ is equal to the rate of appearance of ‘Z’.
Three times the rate of disappearance of ‘X’ is equal to the rate of appearance of ‘Z’.
An example of autothermal reactor operation is
A sulphur dioxide oxidation
B ethylene oxidation
C benzene oxidation
D ammonia synthesis
ETHYLENE OXIDATION
For a packed bed reactor; the presence of a long tail in the residence time distribution curve is an indication of
A ideal plug flow
B bypass
C dead zone
D chanelling
DEAD ZONE
Space time in flow reactor is
A usually equal to the residence time.
B the reciprocal of the space velocity.
C a measure of its capacity.
D both (a) and (b).
usually equal to the residence time.
the reciprocal of the space velocity.
For a first order isothermal chemical reaction in a porous catalyst, the effectiveness factor is 0.3. The effectiveness factor will increase if the
A catalyst size is reduced or the catalyst diffusivity is reduced.
B catalyst size is reduced or the catalyst diffusivity is increased.
C catalyst size is increased or the catalyst diffusivity is reduced.
D catalyst size is increased or the catalyst diffusivity is increased.
catalyst size is reduced or the catalyst diffusivity is increased.
Cold shot cooling is only practical when the feed temperature is __________ than the reaction temperature.
A higher
B much higher
C lower
D much lower
MUCH LOWER
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).
CA = 0.83 CAO (1-X)/ (1-0.33X)
The preferred reacting system for oxidation of o-xylene to phthalic anhydride is
A jacketted liquid phase CSTR.
B jacketted steam heated multitubular reactor.
C multitubular reactor with cooling.
D multistage multitubular reactor with interstage cooling.
JACKETTED LIQUID PHASE CSTR
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)
L(K/D1)
1/(L SQRT K/D1)
1
∞
1/(L SQRT K/D1)
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
A diffusion within the pellet.
B reaction.
C external mass transfer.
D none of the above.
DIFFUSION WITHIN THE PELLET
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.
PELLET DIAMETER 1,2,3
LEAVING CONCENTRATION OF THE REACTANT 1,1,1
SPINNING RATE OF BASKET high, low, high
-rA 2,1,1
A Strong pore diffusion control and mass transfer not controlling.
B Both pore diffusion and mass transfer not controlling.
C Both pore diffusion and mass transfer controlling.
D Mass transfer controlling.
STRONG PORE DIFFUSION CONTROL AND MASS TRANSFER NOT CONTROLLING
