Unit Processes Problems on “Thermodynamics of Nitration”.
1. Is nitration reaction highly exothermic?
a) True
b) False
Answer: a
Clarification: As a huge amount of heat is liberated during nitration reaction therefore it is called exothermic, if heat was to be added it would be called endothermic reaction.
2. What is the denotion of enthalpy?
a) H
b) Q
c) W
d) None of the mentioned
Answer: a
Clarification: the enthalpy of reaction is denoted by H.
3. The total amount of heat lost by the reacting system from the start of the reaction till the products return to the initial temperature and pressure of the system, what is the heat ‘Q’ called?
a) Heat of Formation
b) Heat of reaction
c) Heat of Nitration
d) All of the mentioned
Answer: d
Clarification: Heat of nitration or heat of reaction or heat of formation ‘Q’ is an exothermic reaction, and it is the total amount of heat given out during nitration reaction.
4. Calculate the Heat of nitration “Q”: C6H6 + HNO3 ——-> C6H5NO2 + H2O
Qf: -9.7 kgcal +41.5kgcal—–> -2.3kgcal +68.4kgcal
a) +34.3 kgcal
b) -34.3 kgcal
c) +43.3 kgcal
d) -43.3 kgcal
Answer: a
Clarification: Heat of nitration = product – reactant which is +34.3 kgcal.
5. The heats of nitration decrease with the increase in the number of nitro groups.
a) True
b) False
Answer: a
Clarification: Given by Rinkenbach, the heat of nitration decreases as nitro group increases but heat of formation tends to increase till second and third group and diminishes thereafter.
6. Which of the following has the highest heat of formation?
a) C6H5-NO2
b) C6H5-CH2-NO2
c) C6H5-NH-NO2
d) C6H5-N(-NO2)2
Answer: a
Clarification: It will have the highest amount of heat of formation because as -NO2 group increase it creates strain in molecules hence less amount of heat required the break the bond.
7. Which of the following compounds have high heat of formation? (i) b-(2,3,4) trinitrotoluene (ii) a-(2,4,6) trinitrotoluene .
a) (i) b-(2,3,4) trinitrotoluene
b) (ii) a-(2,4,6) trinitrotoluene
c) Both are equal
d) Only (ii) a-(2,4,6) Dinitrotoluene
Answer: b
Clarification: a-(2,4,6) trinitrotoluene has the highest heat of formation because it is quite stable without any stain within the molecules, and has low internal energy.
8. The heat of formation does not depends upon the internal energy of the molecule.
a) True
b) False
Answer: b
Clarification: The heat of formation does depend upon the internal energy as, as the internal energy is high we get less amount of heat of formation.
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