Free Chemical Reaction Engineering MCQs with Answers
395 Chemical Reaction Engineering MCQs from Chemical Engineering, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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395 questions · page 18 of 20
- A. CSTR of volume V
- B. PFR of volume V
- C. CSTR of volume V/X
- D. PFR of volume V/X
Explanation: Ideal PFRs in series behave as one continuous PFR because each element experiences the same plug-flow progression.
Correct answer: PFR of volume V- A. Equilibrium constant is infinite
- B. Fractional conversion of 'A' at equilibrium is unity
- C. All A., B. and C.
- D. Concentration of 'A' at equilibrium is zero
Explanation: An irreversible reaction is the limiting reversible case with an infinite equilibrium constant.
Correct answer: All A., B. and C.- A. 18
- B. 24
- C. 6
- D. 12
Explanation: A 75% conversion leaves 25% of A, or one-fourth of its initial amount. For a first-order reaction this requires two half-lives, so the…
Correct answer: 24- A. 0.5
- B. -0.5
- C. 1
- D. 1.5
Explanation: For 2A → R, the change in total gas moles is 1 − 2 = −1 for every 2 moles of A consumed.
Correct answer: -0.5345. Arrhenius equation represents graphically the variation between the ______________ and temperature?
- A. Rate constant
- B. Frequency factor
- C. Rate of reaction
- D. Activation energy
Explanation: The Arrhenius relation, k = A exp(−Ea/RT), describes how the rate constant changes with temperature.
Correct answer: Rate constant- A. CSTR
- B. CSTR in series
- C. Recycle reactor
- D. Plug flow reactor
Explanation: A recycle reactor returns product to the feed, which is especially useful when the product catalyses the reaction because it supplies…
Correct answer: Recycle reactor- A. Higher
- B. Much higher
- C. Lower
- D. Much lower
Explanation: Cold-shot cooling removes heat by injecting a colder feed directly into the reacting mixture.
Correct answer: Much lower- A. Temperature of the system
- B. Time of reaction
- C. Extent of reaction
- D. Initial concentration of the reactants
Explanation: The Arrhenius relation, k=A exp(-E/RT), shows that the rate constant is primarily dependent on temperature for a given reaction.
Correct answer: Temperature of the system- A. 500
- B. 0
- C. 750
- D. ∞
Explanation: The dispersion number compares axial mixing with convective transport. Ideal plug flow has no axial dispersion, so D/(uL) approaches zero.
Correct answer: 0- A. Itself has very high activity
- B. Acts as a catalyst support
- C. Improves the activity of a catalyst
- D. All A., B. and C.
Explanation: A promoter is an additive that improves a catalyst's activity, selectivity, or stability, although it may have little catalytic activity…
Correct answer: Improves the activity of a catalyst- A. 1/(time)n
- B. (Concentration)1 - n/(time)
- C. (Concentration)n - 1/(time)
- D. None of these
Explanation: For an nth-order rate law, rate=kC^n, the units of k must make the result concentration per time.
Correct answer: (Concentration)1 - n/(time)- A. Extent of non-ideal flow in the vessel
- B. Reaction mechanism
- C. Activation energies of a reaction
- D. None of these
Explanation: The exit age distribution, or residence-time distribution, shows how long fluid elements remain in the vessel.
Correct answer: Extent of non-ideal flow in the vessel- A. Continuous reaction
- B. Unreacted core
- C. Both A. and B.
- D. Neither A. and B.
Explanation: Fluid-solid non-catalytic reactions are commonly analysed using both the progressive or continuous-reaction model and the unreacted-core…
Correct answer: Both A. and B.- A. Density variation during reaction affects design
- 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. Mixed reactor is always larger than the plug-flow reactor
Explanation: For a positive reaction order, the rate generally decreases as reactants are consumed, so a CSTR operates everywhere at the low exit…
Correct answer: Mixed reactor is always larger than the plug-flow reactor- A. 1/2
- B. 1/3
- C. 1/9
- D. 3
Explanation: Since r is proportional to C_A^n, tripling the rate gives 3 = 9^n. Because 9^(1/2) = 3, the reaction order is n = 1/2.
Correct answer: 1/2- A. e-t/η
- B. e-t/η/η
- C. 1 - e-t/η
- D. 1 - (e-t/η/η)
Explanation: An ideal CSTR has an exponential residence-time distribution, E(t) = (1/η) exp(-t/η), where η is the mean residence time.
Correct answer: e-t/η/η- A. Rate constant
- B. Reaction speed
- C. Conversion
- D. Equilibrium constant
Explanation: The limiting reactant is consumed first according to stoichiometry, so it sets the maximum attainable conversion or theoretical yield.
Correct answer: Conversion- A. Operating conditions (e.g. pressure and temperature)
- B. Rate constant
- C. None of these
- D. Density of mixture
Explanation: For a specified conversion and production rate, the required material amount must be converted into reactor volume using the mixture…
Correct answer: Density of mixture- A. E
- B. E + ΔHA
- C. ΔHA + ΔHR
- D. E + ΔHA - ΔHR)
Explanation: When the denominator is dominated by K_RP_R, the rate is proportional to K K_A/K_R.
Correct answer: E + ΔHA - ΔHR)- A. 190
- B. 290
- C. 390
- D. 490
Explanation: Complete reaction would release 4 kmol/m³ × 50 kJ/mol = 200,000 kJ/m³, producing a temperature rise of 200,000/(1000 × 2) = 100 K.
Correct answer: 290