Unit Processes Questions and Answers – Kinetics, Mechanism and Thermodynamics

This set of Unit Processes Multiple Choice Questions & Answers (MCQs) focuses on “Kinetics, mechanism and thermodynamics”.

1. Which of the following aromatic sulfonation is not an electrophilic substitution reaction?
a) Nitration
b) Halogenation
c) Alkylation
d) None of the mentioned
View Answer

Answer: d
Explanation: Aromatic sulfonation, like nitration, halogenation, alkylation, and acylation, is a typical electrophilic substitution reaction.

2. How does Sulfonation differ from other reactions?
a) Reaction temperature
b) Reversible reaction
c) Both temperature and reversible reaction
d) None of the mentioned
View Answer

Answer: c
Explanation: Sulfonation, differs from these other reactions in two marked respects: it is reversible, and reaction temperature can, in certain cases, have an important influence on the position of the entering group.

3. When H2SO4 is used as a Sulfonating agent, what effect does formation of water has on the reaction?
a) Slows down the reaction
b) Fast the reaction
c) Reduces activation energy
d) None of the mentioned
View Answer

Answer: a
Explanation: When sulfuric acid is used as the sulfonating agent, the formation of water slows the reaction to such degree that rate studies can often be made only during the initial stages, rate of sulfonation is inversely proportional to the square of the water concentration.

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4. Which of the following is a true Sulfonating agent?
a) SO3
b) H3SO4+
c) HSO3+
d) All of the mentioned
View Answer

Answer: d
Explanation: In an aqueous sulfuric acid as many as four different reactive species have been proposed as the true sulfonating agent: (1) H2SO4+, (2) SO3 or a solvate, (3) H80a+ or a solvate, and (4) S2O6 (dimeric SO3).

5. Aromatic substitution reactions, including sulfonation, are conceived in two steps.
a) True
b) False
View Answer

Answer: a
Explanation: Aromatic substitution reactions, including sulfonation, are conceived as proceeding in two steps, the first involving reagent attack and the second proton removal.

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6. Why is the intermediate compound in Sulfonation electrically more stable ?
a) It contains negative charge
b) It contains positive charge
c) It’s neutral
d) None of the mentioned
View Answer

Answer: a
Explanation: The intermediate compound above is electrically neutral and, therefore, more stable than the analogous intermediates involved in nitration and halogenation, which bear positive charges.

7. Complete the following reaction: ROH + H2SO4 <=======> _______ + H2O.
a) RSO2H
b) RSO3H
c) ROSO3H
d) None of the mentioned
View Answer

Answer: c
Explanation: The reaction is as follows: ROH + H2SO4 <=======> ROSO3H + H2O.

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8. Which type of reaction is the heat of Sulfonation reaction?
a) Exothermic
b) Endothermic
c) Neutral
d) None of the mentioned
View Answer

Answer: a
Explanation: The heat of sulfonation with SO3 vapour which is dHv is an exothermic reaction.

9. What is (dH)D ?
a) Heat of Sulfonation
b) Heat of Dissociation
c) Heat of Deformation
d) Heat of Formation
View Answer

Answer: b
Explanation: “(dH)D” is called Heat of Dissociation of Sulfonating agents into SO3 vapor and compound reagent.

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10. What do we denote Heat of Sulfonation with SO3 vapour as?
a) dHv
b) dHD
c) dHc
d) dHf
View Answer

Answer: a
Explanation: dHv is called Heat of sulfonation with vapour SO3 which is an exothermic reaction.

Sanfoundry Global Education & Learning Series – Unit Processes.
To practice all areas of Unit Processes, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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