This set of Unit Processes Multiple Choice Questions & Answers (MCQs) focuses on “Catalystic esterifications”.
1. As temperature increases, what happens to the esterification?
a) Increases
b) Decreases
c) No change
d) None of the mentioned
View Answer
Explanation: The speed of esterification approximately doubles with a 10°C rise in temperature. Hence, heat is used to speed up esterification reactions.
2. How can we fasten the process of esterification?
a) Strong acids
b) Temperature
c) Catalyst
d) All of the mentioned
View Answer
Explanation: Esterification may be enormously hastened by the addition of a strong acid, such as sulfuric or hydrochloric acid. The equilibrium point of the reaction is not altered by the catalyst; only the rate of esterification is increased.
3. Fill in the blank: The larger this positive charge, the more _____ the reaction will be.
a) Slower
b) Faster
c) No change
d) None of the mentioned
View Answer
Explanation: The larger this positive charge, the more rapid the reaction will be.
4. ‘R’ being what increases the esterification process?
a) Positive
b) Negative
c) No change
d) None of the mentioned
View Answer
Explanation: While the nature of the R group attached to the carboxyl group will influence this charge, other methods, or catalysts, can be used to increase the positive charge so that a given acid will esterify more rapidly.
5. What type of compounds are esterification catalyst?
a) Basic
b) Neutral
c) Acidic
d) None of the mentioned
View Answer
Explanation: Esterification catalysts are compounds which are acidic in nature. Acidic compounds, in this case, are those in which the central atom has an incomplete external electron shell, so that besides the hydrogen ion, compounds such as boron trifluoride, aluminium chloride, or zinc chloride can be considered to be acids.
6. Alcohol oxygen also can act as a base.
a) True
b) False
View Answer
Explanation: The alcohol oxygen also can act as a base toward the acid. However, this reaction hinders esterification and, in addition, may lead to dehydration of the alcohol.
7. Which of the following can act as catalyst in esterification process?
a) Sulphuric acid
b) Hydrochloric acid
c) Both H2SO4 and HCl
d) None of the mentioned
View Answer
Explanation: In general practice, hydrochloric and sulfuric acids are the catalysts most commonly used, the former being in favour in the laboratory because of its efficiency and the latter in the plant because of its cheapness and lower corrosive effect on metals.
8. The use of strong acid is disadvantageous.
a) True
b) False
View Answer
Explanation: The use of any strong acid as a catalyst may cause isomerization or destruction of a tertiary alcohol, such as linalool.
9. The presence of what enhances the catalytic effect of acids?
a) Copper oxide
b) Nickel
c) Zinc chloride
d) All of the mentioned
View Answer
Explanation: The presence of zinc chloride seems to enhance the catalytic effect of acids. The addition of a large amount of calcium chloride aids in the separation of water as a layer. Zinc and tin chlorides are said to be active catalysts.
10. A trace of pyridine enhance esterification.
a) True
b) False
View Answer
Explanation: A trace of pyridine was found to retard esterification, while others report large amounts of it to be a more effective catalyst than sulfuric acid.
Sanfoundry Global Education & Learning Series – Unit Processes.
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