1.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
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.
2. For what value of α1,2 ,the separation cannot be achieved?
a) 0.8
b) 1.2
c) 1.3
d) 1.8
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.
3. 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 )
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.
4. 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
Explanation: Since D= F(z F – x B )/(x D – x B ), D=4*(0.7-0.4)(0.5- 0.4)=12.
5. 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
Explanation: Since D= F(z F – x B )/(x D – x B ), D=20*(0.8-0.4)(0.5- 0.4)=80.
6. 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
Explanation: Since D= F(z F – x B )/(x D – x B ), D=9*(0.7-0.3)(0.5- 0.3)=18.
7. 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
Explanation: Since D= F(z F – x B )/(x D – x B ), D=31*(0.9-0.4)(0.6- 0.4)=12.
8. What is λ= KV/L replaced by since the line for distillation is curved?
a) λ= mV/L
b) λ= MVL
c) λ= mL/V
d) λ= mV/K
Explanation: Because the equilibrium line for distillation is curved, λ= KV/L is replaces by λ=mV/L where m is dy/dx.
9. Which of the following is correct?
a) HETP = H OG λ(λ-1)
b) HETP = H OG λ/(λ-1)
c) HETP = H OG /λ(λ-1)
d) HETP = H OG -λ(λ- 1)
Explanation:HETP = H OG λ/(λ-1) is correct where λ= mV/L.
10. Which method uses McCabe-thiele diagram?
a) HETP method
b) HTU method
c) Ponchon-Savarit method
d) HODL method
Explanation: The HETP method used McCabe-thiele diagram first.