Engineering Questions with Answers - Multiple Choice Questions

Home » MCQs » Chemical Engineering » Separation Processes MCQ’s – Rate Based Method for Packed Columns

# Separation Processes MCQ’s – Rate Based Method for Packed Columns

1 - Question

Packed columns are better analyzed by:

a) Mass transfer coefficients

b) Equilibrium stage methods

c) Graphical methods

d) Algebraical methods

**
View Answer**

Answer: aExplanation: Packed columns are better analyzed by mass transfer coefficients.

2 - Question

What is the formula for HETP or HETS?

a) HETP = l T *N T

b) HETP = l T-N T

c) HETP = l T /NT

d) HETP = lT+NT

**
View Answer**

Answer: cExplanation: The formula for HETP is HETP = lT/NT where lT is the packed height length and the N T is the number of equilibrium stages

3 - Question

At the interface of liquid and vapor, which interface exists?

a) Chemical

b) Physical

c) Thermal

d) No equilibrium exists

**
View Answer**

Answer: bExplanation: At the interface of liquid and vapor, a physical equilibrium exists.

4 - Question

Which of the following is the correct illustration of rate of mass transfer?

a) r= ky a(y-y 1 ) =kx a(x-x 1 )

b) r= ky a(y 1 -y) =kx a(x 1 -x)

c) r= ky a(y-y 1 ) =kx a(x 1 -x)

d) r= a(y-y 1 ) =a(x 1 -x)

**
View Answer**

Answer: cExplanation: r= k y a(y-y 1 ) =k xa(x 1 -x) is the correct illustration for rate of adsorption where kya and k x a are volumetric mass transfer coefficients.

5 - Question

Which of the following is the correct representation of overall mass transfer coefficient?

a) 1/Ky a = 1/ky a +K/Kx a

b) 1/Ky a = 1/ky a +K/Ky a

c) 1/Ky a = 1/ky a +1/KKx a

d) Ky a = 1/ky a +K/Kx a

**
View Answer**

Answer: aExplanation: The correct representation of overall mass transfer coefficient is 1/K y a = 1/k y a +K/K x a, where K y is the overall mass transfer coefficient obtained from slope=point form

6 - Question

What is the overall height of gas transfer unit if the volume is 1000m 3 and the overall gas phase coefficient is 2.6 and the inside cross sectional area is 20m 2 .

a) 12m

b) 13.6m

c) 18.9m

d) 19.2m

**
View Answer**

Answer: dExplanation: HOG = V/ky aS, hence HOG= 1000/2.6*20=19.2.

7 - Question

What is the overall height of gas transfer unit if the volume is 780m 3 and the overall gas phase coefficient is 4.2 and the inside cross sectional area is 45m 2 .

a) 4.1m

b) 7.2m

c) 10.4m

d) 19.2m

**
View Answer**

Answer: aExplanation: HOG = V/ky aS, hence HOG= 780/4.2*45=4.1.

8 - Question

What is the overall height of gas transfer unit if the volume is 489m 3 and the overall gas phase coefficient is 1.2 and the inside cross sectional area is 22m 2 .

a) 12m

b) 13.6m

c) 18.5m

d) 19.2m

**
View Answer**

Answer: cExplanation: HOG = V/ky aS, hence HOG= 489/1.2*22=18.5.

9 - Question

What is the packed height length is HETP is 3ft and the number of equilibrium stages is

a) 0.75

b) 1.33

c) 12

d) 16

**
View Answer**

Answer: cExplanation: HETP =lT /NT , hence lT =4*3=12.

10 - Question

What is the packed height length is HETP is 3.8ft and the number of equilibrium stages is

a) 0.76

b) 1.3157

c) 12

d) 19

**
View Answer**

Answer: cExplanation: HETP =lT /NT , hence lT =3.8*5=19.

11 - Question

What is the packed height length is HETP is 6ft and the number of equilibrium stages is

a) 0.76

b) 1.3157

c) 30

d) 19

**
View Answer**

Answer: cExplanation: HETP =lT /NT , hence lT =6*5=30.

12 - Question

What is the packed height length is HETP is 4.2ft and the number of equilibrium stages is

a) 0.76

b) 8.4

c) 12

d) 19

**
View Answer**

Answer: bExplanation: HETP =lT /NT , hence lT =4.2*2=8.4.