Engineering Questions with Answers - Multiple Choice Questions
Unit Processes MCQ’s – Kinetics, Mechanism and Thermodynamics
1 - Question
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
Explanation: Aromatic sulfonation, like nitration, halogenation, alkylation, and acylation, is a typical electrophilic substitution reaction.
2 - Question
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
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 - Question
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
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.
4 - Question
Which of the following is a true Sulfonating agent?
a) SO3
b) H3SO4+
c) HSO3+
d) All of the mentioned
View Answer
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 - Question
Aromatic substitution reactions, including sulfonation, are conceived in two steps.
a) True
b) False
View Answer
Explanation: Aromatic substitution reactions, including sulfonation, are conceived as proceeding in two steps, the first involving reagent attack and the second proton removal.
6 - Question
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
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 - Question
Complete the following reaction: ROH + H2SO4 _______ + H2O.
a) RSO2H
b) RSO3H
c) ROSO3H
d) None of the mentioned
View Answer
Explanation: The reaction is as follows: ROH + H2SO4 ROSO3H + H2O.
8 - Question
Which type of reaction is the heat of Sulfonation reaction?
a) Exothermic
b) Endothermic
c) Neutral
d) None of the mentioned
View Answer
Explanation: The heat of sulfonation with SO3 vapour which is dHv is an exothermic reaction.
9 - Question
What is (dH)D ?
a) Heat of Sulfonation
b) Heat of Dissociation
c) Heat of Deformation
d) Heat of Formation
View Answer
Explanation: “(dH)D” is called Heat of Dissociation of Sulfonating agents into SO3 vapor and compound reagent.
10 - Question
What do we denote Heat of Sulfonation with SO3 vapour as?
a) dHv
b) dHD
c) dHc
d) dHf
View Answer
Explanation: dHv is called Heat of sulfonation with vapour SO3 which is an exothermic reaction.