This set of Separation Processes Multiple Choice Questions & Answers (MCQs) focuses on “McCabe-Thiele Graphical Method for Trayed Towers”.
1. What is the goal of distillation?
a) To produce a distillate rich in light key and the bottoms product rich in high key
b) To produce a distillate rich in high key and the bottoms product rich in light key
c) To produce a distillate rich in light key and the bottoms product rich in light key
d) To produce a distillate rich in high key and the bottoms product rich in high key
View Answer
Explanation: The goal of distillation is to produce a distillate rich in light key and the bottoms product rich in high key.
2. What is meant by light key (LK)?
a) A feed that contains less volatile components
b) A feed that has less mass
c) A feed that has higher concentration of less molecular weight solute
d) A feed that contains more volatile components
View Answer
Explanation: Light key is the feed that contains more volatile components.
3. What is meant by high key (HK)?
a) A feed that contains less volatile components
b) A feed that has less mass
c) A feed that has higher concentration of less molecular weight solute
d) A feed that contains more volatile components
View Answer
Explanation: High key is the feed that contains less volatile components.
4. If LK=1 and HK=2, what is the formula for α 1,2 ?
a) α 1,2 =K1/K2
b) α 1,2 =K1*K2
c) α 1,2 =K1-K2
d) α 1,2 =K1+K2
View Answer
Explanation: To find out whether the separation is possible or not α 1,2 values are used whose formula is α 1,2 =K1/K2.
5. For what value of α1,2 ,the separation cannot be achieved?
a) 0.8
b) 1.2
c) 1.3
d) 1.8
View Answer
Explanation: For α1,2 = 0.8, the separation cannot be achieved since its value has to be greater
than 1.Thus by further increasing pressure, separation cannot be achieved.
6. What is the formula for distillation rate according to mcCabe-thiele’s method?
a) D= F(z F – x B )/(x D + x B )
b) D= F(z F – x B)/(x D /x B )
c) D= F(z F – x D )/(x D – x B )
d) D= F(z F – x B )/(x D – x B )
View Answer
Explanation: D= F(z F – x B )/(x D – x B ) is the correct equation where D is the distillation rate, F is the total feed rate, z F is the mole fraction of LK in feed, x D , x B are mole fractions of LK in distillate and bottom.
7. What is the distillation rate if feed rate is 4moles/s and mole fraction of LK in feed is 0.7, and mole fraction of LK in distillate and bottom is 0.5, 0.4?
a) 8moles/s
b) 12moles/s
c) 16moles/s
d) 20moles/s
View Answer
Explanation: Since D= F(z F – x B )/(x D – x B ), D=4*(0.7-0.4)(0.5- 0.4)=12.
8. What is the distillation rate if feed rate is 20moles/s and mole fraction of LK in feed is 0.8, and mole fraction of LK in distillate and bottom is 0.5, 0.4?
a) 80moles/s
b) 12moles/s
c) 16moles/s
d) 20moles/s
View Answer
Explanation: Since D= F(z F – x B )/(x D – x B ), D=20*(0.8-0.4)(0.5- 0.4)=80.
9. What is the distillation rate if feed rate is 9moles/s and mole fraction of LK in feed is 0.7, and mole fraction of LK in distillate and bottom is 0.5, 0.3?
a) 45moles/s
b) 16moles/s
c) 18moles/s
d) 20moles/s
View Answer
Explanation: Since D= F(z F – x B )/(x D – x B ), D=9*(0.7-0.3)(0.5- 0.3)=18.
10. What is the distillation rate if feed rate is 31moles/s and mole fraction of LK in feed is 0.9, and mole fraction of LK in distillate and bottom is 0.6, 0.4?
a) 23moles/s
b) 26moles/s
c) 28moles/s
d) 31moles/s
View Answer
Explanation: Since D= F(z F – x B )/(x D – x B ), D=31*(0.9-0.4)(0.6- 0.4)=12.
Sanfoundry Global Education & Learning Series – Separation Processes.
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