Distillation Design Questions and Answers – Vapour Liquid Equilibrium

This set of Distillation Design Multiple Choice Questions & Answers (MCQs) focuses on “Vapour Liquid Equilibrium”.

1. Which of the following shows the correct Gibbs phase rule equation?
a) F=C-P+2
b) P=C+P
c) C=F-P+2
d) C=P-F
View Answer

Answer: a
Explanation: According to Gibb’s F=C-P+2 for any system, where F is degree of freedom, C is number of components and P is the number of phases.

2. The higher the concentration of volatile species, the distillation
a) The higher the rate of liquid flow
b) The lower the rate of Separation
c) The higher the rate of separation
d) Cannot be specified
View Answer

Answer: c
Explanation: Volatility is directly proportional to the ease of separation (α) while it is inversely proportional to difficulty of separation.

3. VLE data once obtained is represented on which scale?
a) Binary Scale (0<x<1)
b) Pressure Scales (0<Pa<1)
c) Temperature Ranges (T1<x<T2)
d) Not specific
View Answer

Answer: a
Explanation: Binary scales are most suitable as they represent mole fractions of the both species x* and y* at all conditions.
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4. When the boiling temperature is plotted against the liquid composition, then it is called
a) Cooling Curve
b) Heating Curve
c) Bubble point curve
d) Volatility Phase Diagram
View Answer

Answer: c
Explanation: The (T-x) curve is called as Bubble point Curve, Where T is boiling temperature and x is the mole fraction of the liquid.

5. When the temperature is plotted against the equilibrium vapor, then it is called
a) Condensing Curve
b) Dew Point curve
c) Equilibrium Curve
d) Bubble Curve
View Answer

Answer: b
Explanation: The (T-y*) curve is called as Dew point Curve, Where T is boiling temperature, and y is the equilibrium moles of the gaseous components.

6. The K value can be expressed as
a) y/x
b) yi/x
c) x/y
d) yi/xi
View Answer

Answer: d
Explanation: The ratio of mole fraction of components in vapor and liquid phase is called as K value.

7. The Relative Volatility of components i and j can be defined as
a) Ki/Kj
b) K/Kj
c) yi/y
d) xi/x
View Answer

Answer: a
Explanation: The ratio of K values is defined as the relative volatility, Where Ki is the gaseous components and Kj is the fluid components.
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8. Given that αAB=2.0, Then equilibrium ratio of B is KB=0.7, Estimate αBA ?
a) 0.9
b) 0.65
c) 0.5
d) 0.6
View Answer

Answer: c
Explanation: As α=KB/KA, 2.0= 0.7/KA, KA = 0.35 and αAB =KA/KB =0.35/0.7 = 0.5.

9. Which system can be said as an Ideal system that obeys?
a) Henrys Law
b) Daltons Law
c) Phase Rule
d) Cremer’s rule
View Answer

Answer: d
Explanation: The system that obeys Henry’s and Dalton’s Law is called an ideal system, as they are derived from the ideal gas relation PV=Nrt.
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10. Which of the below is the Dalton’s Law?
a) pi = yi/P
b) x = yi/ pi
c) pi = yi/x
d) pi = xi/y
View Answer

Answer: a
Explanation: According to Dalton’s law the partial pressure of component is solution is equal to product of its mole fraction and vapor pressure of pure components.

Sanfoundry Global Education & Learning Series – Distillation Design.
To practice all areas of Distillation Design, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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