Free Chemical Reaction Engineering MCQs with Answers

• A. Unimolecular reaction with first order
• B. Bimolecular reaction with second order
• C. Bimolecular reaction with first order
• D. Unimolecular reaction with second order

Explanation: Inversion involves sucrose reacting with water, so its molecularity is bimolecular.

• A. 0.03 sec-1
• B. 0.03 min-1
• C. 0.03 hr-1
• D. 0.05 min-1

Explanation: For a first-order reaction, the half-life relation is k = 0.693/t₁/₂. Thus k = 0.693/23 = 0.030 min⁻¹, making option b correct.

• A. Autokinetic
• B. Non-elementary
• C. Parallel
• D. Elementary

Explanation: An elementary reaction occurs in a single molecular event, so its rate equation follows the stoichiometric equation directly.

• A. Feasibility
• B. Rate
• C. Both A. & B.
• D. Neither A. nor B.

Explanation: Chemical kinetics determines how fast a reaction proceeds through its rate law and rate constant.

• A. Lose an electron
• B. Gain a proton
• C. Lose a proton
• D. None of these

Explanation: Acid catalysis involves proton donation, so the catalytic species must have a tendency to lose a proton.

• A. Always spontaneous
• B. Slow
• C. Non-spontaneous
• D. Fast

Explanation: The Arrhenius relation shows that a lower activation energy gives a larger rate constant at the same temperature, so the reaction is…

• A. All A., B. and C.
• B. Pressure only
• C. Composition only
• D. Temperature only

Explanation: An autocatalytic reaction rate depends on composition because a product participates in catalysis, and it also varies with temperature…

• A. Batch
• B. Slurry
• C. Fluidised bed
• D. Fixed bed

Explanation: Vegetable-oil hydrogenation commonly uses finely divided nickel suspended with the liquid oil and hydrogen, forming a slurry reactor.

• A. Biochemical
• B. Photochemical
• C. Autocatalytic
• D. Catalytic

Explanation: When a product accelerates the reaction that forms it, the reaction is called autocatalytic.

• A. For testing complicated mechanisms
• B. When the data are scattered
• C. When rate expressions are very simple
• D. None of these

Explanation: The differential method obtains reaction rates by differentiating concentration data, so it is useful for testing complicated rate…

• A. Time
• B. Length
• C. Diameter
• D. None of these

Explanation: In a tubular or plug-flow reactor, concentration and temperature vary primarily along the reactor axis.

• A. Non-catalytic homogeneous
• B. Non-catalytic heterogeneous
• C. Catalytic homogenous
• D. Catalytic heterogeneous

Explanation: In the chamber process, sulphur dioxide is oxidised in the gas phase with nitrogen oxides acting as catalysts.

• A. Equilibrium constant
• B. Heat of reaction
• C. Heat of formation of the product
• D. Activation energy

Explanation: A catalyst provides an alternative reaction pathway with a lower activation energy, thereby increasing the rate in both directions.

• A. η = θ, for an isothermic tubular reactor in which the density of the process fluid is constant
• B. η = θ, when the fluid density changes in the reactor
• C. η and θ are always equal
• D. η = θ, for a non-isothermal reactor

Explanation: Space time equals residence time when the fluid density, and hence volumetric flow rate, remains constant through the reactor.

• A. Batch
• B. Mixed
• C. Plug-flow
• D. None of these

Explanation: A mixed-flow reactor gives uniform concentration and temperature throughout the reacting mixture, making the rate easier to evaluate for a…

• A. 1/(time)(concentration)n - 1
• B. (Time)-1 (concentration)n - 1
• C. (Time)n - 1 (concentration)
• D. None of these

Explanation: For -r = kC^n, the rate constant has units of concentration^(1-n) per time, equivalent to 1 divided by time times concentration^(n-1).

• A. Porosity of the catalyst bed
• B. Pore size distribution
• C. Pore diameter
• D. Specific surface of a porous catalyst

Explanation: BET adsorption analysis measures the specific surface area by determining the amount of gas required to form a monolayer on the solid.

• A. Pore diffusion
• B. Gas film
• C. Chemical reaction
• D. None of these

Explanation: The effectiveness factor compares the actual pellet reaction rate with the rate if internal diffusion caused no limitation, so it…

• A. (i) endothermic (ii) exothermic
• B. (i) exothermic (ii) exothermic
• C. (i) endothermic (ii) endothermic
• D. (i) exothermic (ii) endothermic

Explanation: Catalytic cracking consumes heat, so it is endothermic, while burning the deposited coke during catalyst regeneration releases heat and is…

• A. High capacity
• B. Presence of lateral mixing
• C. Presence of axial mixing
• D. Constant composition and temperature of reaction mixture

Explanation: An ideal plug-flow reactor has no axial mixing, but fluid elements can mix laterally or radially.