chemical engineering chemical reaction MCQs – Page 7

Practise multiple-choice questions from chemical engineering chemical reaction for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering chemical reaction Mcqs

121. 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?
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A. Both conversion as well as concentration are same

B. 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

122. Which of the following does not produce a change in the value of rate constant of a reaction ?
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A. Temperature

B. None of these

C. Concentration and catalyst

D. Pressure

123. The catalyst in a first order chemical reaction changes the_________________?
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A. Equilibrium constant

B. Heat of formation of the product

C. Heat of reaction

D. Activation energy

124. Brunauer, 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 ?
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A. Langmuirs assumption applies to every adsorbed layer

B. None of these

C. The adsorbed layer may be polymolecular in thickness and the heat of adsorption in each layer

D. There is no dynamic equilibrium between successive layer

E. cept the first one) is involved in each of the evaporation process

125. A pulse tracer is introduced in an ideal CSTR (with a mean residence time I) at time, t = 0. The time taken for the exit concentration of the tracer to reach half of its initial value will be__________________?
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A. 2?

B. 0.5?

C. ?/0.693

D. 0.693?

126. The use of space time is preferred over the mean residence time in the design of a/an____________________?
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A. Slurry reactor

B. CSTR

C. Batch reactor

D. Ideal tubular-flow reactor

127. The reaction rate constants at two different temperatures T1 and T2 are related by _________________?
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A. exp (k2/k1) = (E/R) (1/T2 1/T1)

B. ln (k2/k1) = (E/R) (1/T2 1/T1)

C. exp (k2/k1) = (E/R) (1/T1 1/T2)

D. ln (k2/k1) = (E/R) (1/T1 1/T2)

128. B.E.T. method of finding out surface area of a catalyst, uses the extension of _________________ isotherm?
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A. Tempkin

B. Langmuir

C. None of these

D. Freundlich

129. Higher free energy of activation of a chemical reaction (at a given temperature) implies ____________________?
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A. Slower rate of reaction

B. Higher rate of reaction

C. Higher equilibrium conversion

D. Both B. and C.

130. A catalyst inhibitor____________________?
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A. May be useful for suppressing undesirable side reactions

B. Lessens its selectivity

C. Is added in small quantity during the catalyst manufacture itself

D. All A., B. and C.

131. The conversion for a second order, irreversible reaction (constant volume) as shown in the bellow figure, in batch mode is given by______________?
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A. 1/(1 + k2 . CA0 . t)

B. (k2 . CA0 . t)2/ (1 + k2 . CA0 . t)

C. (k2 . CA0 . t)/ (1 + k2 . CA0 . t)

D. (k2 . CA0 . t)/ (1 + k2 . CA0 . t)2

132. The effectiveness factor for large value of Thiele modulus [L?(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) ?
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A. 1/[L?(K/D1)]

B. ?

C. 1

D. L ?(K/D1)

133. For the liquid phase parallel reactions__________________?
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A. High temperature in a PFR

B. Low temperature in a CSTR

C. Low temperature in a PFR

D. rR = K1.CA2; E1 = 80 KJ/mole

E. desired product is R. A higher selectivity of R will be achieved, if the reaction is conducted

F. rs = K1.CA ; E2 = 120 KJ/mole

134. Volume change for unimolecular type first order reaction as shown in the bellow figure, increases _____________ with time?
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A. Linearly

B. Exponentially

C. Logarithmically

D. Parabolically

135. For a first order isothermal chemical reaction in a porous catalyst, the effectiveness factor is 0.3. The effectiveness factor will increase if the____________________?
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A. Catalyst size is increased or the catalyst diffusivity is reduced

B. Catalyst size is reduced or the catalyst diffusivity is increased

C. Catalyst size is reduced or the catalyst diffusivity is reduced

D. Catalyst size is increased or the catalyst diffusivity is increased

136. The reaction A ? B is conducted in an adiabatic plug flow reactor (PFR). Pure A at a concentration of 2 kmol/m3is 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)) ?
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A. 500

B. 400

C. 1000

D. 600

137. With increase in temperature, the rate constant obeying Arrhenius equation____________________?
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A. Can either increase or decrease; depends on the frequency factor

B. Decreases

C. Increases

D. Decreases exponentially

138. Which of the following is the optimum operating condition for an exothermic reversible reaction taking place in a plug-flow reactor ?
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A. None of these

B. Very low temperature should be used throughout the reaction

C. Temperature should be high in the beginning and decreased towards the end of the reaction

D. Very high temperature should be used throughout the reaction

139. Arrhenius equation represents graphically the variation between the ______________ and temperature?
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A. Frequency factor

B. Rate of reaction

C. Rate constant

D. Activation energy

140. The preferred reacting system for oxidation of o-xylene to phthalic anhydride is _____________________?
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A. Multistage multitubular reactor with interstage cooling

B. Jacketed liquid phase CSTR

C. Multitubular reactor with cooling

D. Jacketed steam heated multitubular reactor

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