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 19 of 20
- A. CA
- B. CA3
- C. CA2
- D. CA4
Explanation: If r is proportional to C_A^n, doubling concentration changes the rate by 2^n.
Correct answer: CA2- A. Very slow
- B. Very fast
- C. Photochemical
- D. Both B. and C.
Explanation: Formation of a latent photographic image is initiated by light, making it a photochemical reaction, and the exposure process is very…
Correct answer: Both B. and C.- A. 0
- B. 0.5
- C. 1
- D. 2
Explanation: For r proportional to C_A^n, doubling concentration gives 2^n = 2. Hence n = 1, so the reaction is first order in A.
Correct answer: 1- A. Reaction rate
- B. Rate constant
- C. Energy of activation
- D. Frequency factor
Explanation: The Arrhenius relation, k = A exp(-Eₐ/RT), describes how the rate constant changes with temperature.
Correct answer: Rate constant- A. Reactant's concentration
- B. Pressure
- C. Temperature
- D. None of these
Explanation: For a given reaction, the rate constant generally increases with temperature because more molecules can overcome the activation-energy…
Correct answer: Temperature- A. 0
- B. 1
- C. < 1
- D. ∞
Explanation: A CSTR is assumed to be perfectly mixed, so its axial concentration gradient is completely dispersed.
Correct answer: ∞- A. Increases the speed of a
- B. Can either increase or decrease the speed of a
- C. Decreases the speed of a
- D. Alters the value of equilibrium constant in a reversible
Explanation: A catalyst changes reaction speed by providing an alternative pathway with a different activation energy, and it may either accelerate or…
Correct answer: Can either increase or decrease the speed of a368. The equilibrium constant of a catalytic chemical reaction _______________ due to the presence of?
- A. Remain unaffected
- B. Increases
- C. Decreases
- D. a catalyst.
- E. Unpredictable from the data
Explanation: A catalyst changes the rates of forward and reverse reactions without changing their thermodynamic balance.
Correct answer: Remain unaffected- A. d(VCA)/dt = -F (CAF - CA) - kCA2V
- B. d(VCA)/dt = F (CAF - CA) - kCA2V
- C. d(VCA)/dt = -FCA - kCA2V
- D. d(VCA)/dt = FCAF - kCA2V
Explanation: With no outlet stream, A enters at F C_AF and is consumed at kC_A²V. Thus accumulation equals feed minus reaction consumption: d(VC_A)/dt…
Correct answer: d(VCA)/dt = FCAF - kCA2V- A. Catalyst size is reduced or the catalyst diffusivity is increased
- B. Catalyst size is reduced or the catalyst diffusivity is reduced
- C. Catalyst size is increased or the catalyst diffusivity is reduced
- D. Catalyst size is increased or the catalyst diffusivity is increased
Explanation: Effectiveness improves when internal diffusion resistance decreases. Reducing catalyst size shortens the diffusion path, while increasing…
Correct answer: Catalyst size is reduced or the catalyst diffusivity is increased- A. Catalyst
- B. Number of molecules of reactants taking part in the reaction
- C. Reactant's concentration
- D. Temperature
Explanation: Reaction rate is governed by factors such as reactant concentration, temperature and catalytic effects, not by simply counting the…
Correct answer: Number of molecules of reactants taking part in the reaction- A. Solid density
- B. Pore volume
- C. Surface area
- D. All A., B. and C.
Explanation: The BET adsorption method measures the specific surface area of a porous solid from the amount of gas adsorbed.
Correct answer: Surface area- A. Either A. or B., depends on order of reaction
- B. Less
- C. Same
- D. More
Explanation: An exothermic reaction releases energy, so the products lie at a lower energy level than the reacting substances.
Correct answer: More- A. A highly exothermic reaction is to be controlled
- B. All A., B., and C.
- C. A gas is to be reacted with liquid (e.g. hydrogenation of fat)
- D. Undesirable side reaction (at high concentration of one of the reactants) is to be avoided
Explanation: Semibatch operation permits gradual addition of a reactant, helping control heat release and preventing high reactant concentrations that…
Correct answer: All A., B., and C.- A. CA0/K
- B. CA0/2K
- C. 0.693/K
- D. 1/K
Explanation: For a zero-order reaction, the concentration relation is C_A=C_A0−kt. Setting C_A=C_A0/2 gives t_1/2=C_A0/(2k), unlike a first-order…
Correct answer: CA0/2K- A. Pore
- B. Ash layer
- C. Film
- D. None of these
Explanation: At very high temperature, the chemical reaction is usually fast, so transport through the external gas film becomes the limiting step.
Correct answer: Film- A. Pressure and temperature only
- B. Temperature and composition only
- C. Pressure and composition only
- D. Pressure, temperature and composition
Explanation: Homogeneous reaction rates can change with composition through concentration, with temperature through the rate constant, and with…
Correct answer: Pressure, temperature and composition- A. Equal in size
- B. Of different sizes
- C. Of such size that the ratio of their volumes is < 5
- D. None of these
Explanation: For two CSTRs carrying out a first-order reaction, minimizing total volume requires equal concentration-ratio reductions in the two…
Correct answer: Equal in size- A. Gas film
- B. Ash
- C. Chemical reaction
- D. None of these
Explanation: Carbon combustion produces gaseous products such as CO or CO₂, not a solid ash layer that must be penetrated.
Correct answer: Ash- A. 0
- B. 1
- C. 2
- D. 3
Explanation: With rate proportional to C_A^n, doubling concentration changes the rate by 2^n.
Correct answer: 3