Unit Processes Multiple Choice Questions on “Physical and Chemical properties”.
1. Which of the following does not affect the reaction rate?
a) Solubility
b) Agitation
c) Nitro group
d) None of the mentioned
Answer: d
Clarification: A number of factors accelerate or retard the replacement of atoms or radicals by the amino group. These will be discussed in the following order: (1) solubility, (2) agitation, (3) halogen derivative treated, (4) presence of nitro groups, and (5) temperature of amination and NH3 concentration.
2. Anthraquinonesulfonic acids are more readily converted to amines than the insoluble halogen compounds.
a) True
b) False
Answer: a
Clarification: The soluble anthraquinonesulfonic acids are more readily converted to amines than the insoluble halogen compounds.
3. Which factor increases the partial pressure in a reaction?
a) NH3 concentration
b) Heat
c) Agitation
d) All of the mentioned
Answer: a
Clarification: Reaction can be facilitated by increasing either the NH3 concentration or the temperature, as both the factors incidentally increase the partial pressure or activity of the dissolved ammonia.
4. When we dilute NH3 solution, does the reaction suffer?
a) Yes
b) No
Answer: a
Clarification: When more dilute NH3 solutions are employed, the results obviously suffer from the increased activity of the solvent-water.
5. Homogeneity of reaction is highly important in which phase?
a) Vapour
b) Liquid
c) Solid
d) All of the mentioned
Answer: b
Clarification: In liquid-phase ammonolysis, the rate of amination depends upon the homogeneity of the reaction mass.
6. Liquid phase reaction are possible without agitation.
a) True
b) False
Answer: b
Clarification: Without agitation, some insoluble compounds would, on account of their greater density, settle to the bottom of the autoclave while the ammonia liquor remained as a distinct layer above it. Reaction would then take place only at the interface, and a complete conversion of the compound to the amino derivative would not be feasible.
7. Are emulsifying and wetting agents important amination process?
a) Yes
b) No
Answer: a
Clarification: The efficacy of emulsifying and wetting agents are important in the amination process. Such agents appear to have important potential utility in the ammonolysis of aryl halides.
8. The replacement of Br atom is easier than Cl atom.
a) True
b) False
Answer: a
Clarification: From the known activity of the halogens and the heats of formation of the halides, it would be expected that replacement of bromine atoms could be accomplished more readily than that of chlorine atoms.
9. The conversion of chlorobenzene to aniline requires what temperature?
a) Below 50°C
b) 100°C
c) 150°C
d) Above 200°C
Answer: d
Clarification: The conversion of chlorobenzene to aniline requires a comparatively high temperature-200°C or above-and the presence of a catalyst.
10. By the introduction of which group makes the replacement of halogen atom faster?
a) Positive group
b) Negative group
c) Both of the mentioned
d) None of the mentioned
Answer: b
Clarification: By the introduction negative groups such as the -NO2 or -COOH in the ortho or para position of the phenyl nucleus, the replacement of the halogen atom takes place more readily.
11. The introduction of more than one nitro group greatly decreases the activity of the halogen atom.
a) True
b) False
Answer: b
Clarification: The introduction of more than one nitro group greatly increases the activity of the halogen atom.
12. What is meant by Ammonia factor?
a) Ammonia concentration
b) Intensity factor
c) Capacity factor
d) All of the mentioned
Answer: c
Clarification: Ammonia ratio means Capacity factor, whereas Ammonia concentration means intensity factor.
13. Which of the following is/are the advantage for using excess NH3?
a) Rapid amination
b) Complete reaction
c) Large quantity
d) All of the mentioned
Answer: d
Clarification: by utilizing a more concentrated NH3 solution for non-catalytic aminations may be summed up as follows: (1) amination is more rapid, (2) conversion of reacting compound to primary amine is more complete, (3) formation of secondary and tertiary amines and hydroxy compounds is inhibited, (4) lower reaction temperatures can be used, and (5) since larger batches can be treated.
14. The reaction-rate with aryl chlorides depends on what?
a) Ammonia ratio
b) Reaction temperature
c) Halogen compound
d) All of the mentioned
Answer: d
Clarification: Reaction-rate studies with aryl chlorides showed that the effect of NH3 concentration on the rate of conversion in catalytic ammonolysis depends upon (1) the ammonia ratio, (2) the reaction temperature, and (3) the halogen compound.