This set of Unit Processes Multiple Choice Questions & Answers (MCQs) focuses on “Apparatus for Oxidation”.
1. Why is removal of heat essential?
a) Low reaction rate
b) Prevent destruction
c) Uncontrolled oxidation
d) All of the mentioned
View Answer
Explanation: Removal of heat is essential to prevent destruction of apparatus, catalyst, or raw material, and maintenance of temperature at the proper level is necessary to ensure the correct rate and degree of oxidation.
2. Why is reacting O2 less for aromatic hydrocarbon than aliphatic hydrocarbon?
a) More oxidation
b) High temperature
c) Desired product
d) All of the mentioned
View Answer
Explanation: In vapour-phase oxidation of aliphatic substances such as methanol and the lower-molecular-weight aliphatic hydrocarbons, the ratio of reacting oxygen is generally lower than in the case of the aromatic hydrocarbons for the formation of the desired products, and for this reason heat removal is simpler.
3. What is the use of a Liquid bath?
a) Increase temperature
b) Supplies heat
c) Removes heat
d) Provides O2
View Answer
Explanation: The liquid bath may be used to remove heat from the reaction as latent heat of evaporation of the liquid.
4. What is the use of Mercury in multiple-tube converter?
a) Removes heat
b) Supplies heat
c) Catalyst
d) Slows the reaction
View Answer
Explanation: The mercury (liquid and vapour) is the means for removing the heat of a reaction at a constant temperature of about 425°C and for dissipating it to cooling water at a temperature of about 100°C.
5. What happens on varying the pressure on the two-phase mercury system?
a) High temperature
b) Control the temperature
c) More reaction
d) All of the mentioned
View Answer
Explanation: By varying the pressure on the two-phase mercury system, it is possible to control the temperature of the liquid bath and of the catalyst mass. This may be accomplished by the use of nitrogen pressure.
6. Boiling point of Hg can be altered by which alloy?
a) Nickel
b) Magnesium
c) Cadmium
d) All of the mentioned
View Answer
Explanation: The boiling point of the mercury can be altered by introducing alloying metals such as cadmium.
7. Mercury has both advantages and disadvantages.
a) True
b) False
View Answer
Explanation: Mercury has both advantages and disadvantages for use as the heat removing fluid. Its boiling point of 357°C at atmospheric pressure may be easily raised to 400-450°C by the application of nitrogen pressure. It is fluid at room temperature and introduces no hazard of equipment damage due to solidification through accidental cooling because of shutdown of equipment. Mercury vapour is toxic; the liquid is heavy; and leaks in the pressure system are difficult to prevent.
8. Catalysts are generally used in an effort to obtain the oxidation reaction at as Iowa temperature.
a) True
b) False
View Answer
Explanation: Catalysts are generally used in an effort to obtain the oxidation reaction at as Iowa temperature as possible and to direct the reaction, to the desired products.
9. Side chain are more susceptible to be attack on than the ring of aromatic compounds.
a) True
b) False
View Answer
Explanation: Oxidation of hydrocarbons containing an aromatic nucleus and one or more aliphatic side chains may be effected in the side chain. The side chains behave, in general, like aliphatic hydrocarbons and, as such, are more susceptible to attack by oxygen than the ring.
Sanfoundry Global Education & Learning Series – Unit Processes.
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