This set of Basic Chemical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Condensation”.
1. Which of the following defines condensation?
a) Change of solid to vapor
b) Change of vapor to liquid
c) Change of liquid to vapor
d) Change of vapor to solid
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Explanation: Condensation is phase change from vapor to liquid.
2. Which of the following is not a way of condensation of vapor?
a) Cooling at constant volume
b) Cooling at constant pressure
c) Compress it isothermally
d) Compress it
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Explanation: Compressing a gas and its temperature is increasing does not condense the vapor, compressing vapor at constant temperature is a way of condensation.
3. Condensation starts at which point?
a) Dew point
b) Bubble point
c) Triple point
d) None of the mentioned
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Explanation: A dew point is a temperature at which condensation starts.
4. If the fraction of water vapor at 27oC and 5 atm is 0.5, then what is the fraction of water vapor at 27oC and 1 atm?
a) 0.1
b) 0.2
c) 0.5
d) 0.8
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Explanation: Fraction of water vapor at 27oC and 1 atm = 0.5/5 = 0.1.
5. What is the fraction of water vapor at 27oC and 1 atm, if the fraction of water vapor at 127oC and 1 atm is 0.8?
a) 0.2
b) 0.4
c) 0.6
d) 0.8
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Explanation: Fraction of water vapor at 127oC and 1 atm = 0.8*300/400 = 0.6.
6. A process is carried out for the feed mixture of 90% air and 10% water vapor, the compressor recovered 90% of water, what is the exit pressure of the compressor if the partial pressure of water vapor is 50 mm Hg?
a) 286.1 mm Hg
b) 396.4 mm Hg
c) 458.7 mm Hg
d) 529.5 mm Hg
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Explanation: Exit components, water: 0.1*0.1 = 0.01, air: 0.9, => water = 0.0109 => Total exit pressure = 50/0.109 = 458.7 mm Hg.
7. A process is carried out for the feed mixture of 95% air and 5% ammonia vapor, the compressor recovered 40% of ammonia, what is the exit pressure of the compressor, if the partial pressure of ammonia vapor is 10 mm Hg?
a) 225.4 mm Hg
b) 326.8 mm Hg
c) 451.2 mm Hg
d) 593.5 mm Hg
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Explanation: Exit components, ammonia: 0.05*0.6 = 0.03, air: 0.95, => yammonia = 0.03/0.98 = 0.0306, => Total exit pressure = 10/0.0306 = 326.8 mm Hg.
8. A process is carried out for the feed mixture of 80% air and 20% CO2, the compressor recovered 50% of CO2, what is the exit pressure of the compressor, if the partial pressure of CO2 is 15 mm Hg?
a) 135 mm Hg
b) 145 mm Hg
c) 175 mm Hg
d) 200 mm Hg
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Explanation: Exit components, CO2: 0.2*0.5 = 0.1, air: 0.8, => yCO2 = 0.1/0.9 = 0.111, => Total exit pressure = 15/0.111 = 135 mm Hg.
9. A process is carried out for the feed mixture of 50% air and 50% methane vapor, the compressor recovered 20% of methane, what is the exit pressure of the compressor, if the partial pressure of methane vapor is 25 mm Hg?
a) 56.3 mm Hg
b) 78.9 mm Hg
c) 92.1 mm Hg
d) 98.7 mm Hg
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Explanation: Exit components, methane: 0.5*0.8 = 0.4, air: 0.5, => ymethane= 0.4/0.9 = 0.444, => Total exit pressure = 25/0.444 = 56.3 mm Hg.
10. A process is carried out for the feed mixture of 40% air and 60% oxygen, the compressor recovered 2% of oxygen, what is the exit pressure of the compressor, if the partial pressure of oxygen vapor is 5 mm Hg?
a) 2.4 mm Hg
b) 4.8 mm Hg
c) 6.5 mm Hg
d) 8.4 mm Hg
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Explanation: Exit components, oxygen: 0.6*0.98 = 0.588, air: 0.4, => yoxygen= 0.588/0.988 = 0.595, => Total exit pressure = 5/0.595 = 8.4 mm Hg.
Sanfoundry Global Education & Learning Series – Basic Chemical Engineering.
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