Separation Processes Questions and Answers - Equipment for Solvent Extraction(b)

1. Why is HETP larger than for staged devices?
a) To avoid overflow
b) To avoid back-mixing
c) To avoid the cost increment
d) To get full efficiency

Answer: b
Explanation: To avoid back-mixing, HETP is larger for staged devices thus packed columns are used only when few stages are required.

2. What is the use of plate columns?
a) Increases axial mixing
b) Reduces axial mixing by packing columns
c) Reduces axial mixing and promotes a stage-wise type of contact
d) Reduces the cost

Answer: c
Explanation:Since it is a shape of a plate, there is a stage-wise contact and also axial mixing is reduced.

3. Why are the extraction rates in sieve plate columns high?
a) Because the dispersed droplets coalesce and reform on each plate
b) Because the dispersed droplets don’t coalesce and reform on each plate
c) Because the dispersed droplets coalesce and not reform on each plate
d) Because the dispersed droplets neither coalesce nor reform on each plate

Answer: a
Explanation: Since the dispersed droplets coalesce and reform on each plate, the extraction rates in sieve plate columns high.

4. How is agitation not induced in columns?
a) Oscillating pulse to liquid
b) Rotating agitators
c) By moving plates back and forth
d) By using mixers

Answer: d
Explanation: Mixers are not used in columns.

5. How agitation is achieved in the scheibel column?
a) Liquid phases are contacted in fixed intervals by unbafled, flat bladed, turbine type agitators
b) By moving plates
c) By hands
d) Gravity separation

Answer: a
Explanation:Liquid phases are contacted in fixed intervals by unbafled, flat bladed, turbine type agitators in scheibel column.

6. What type of agitator is rotating disk agitator?
a) Rotating agitator
b) By moving plates
c) By hands
d) Gravity separation

Answer: a
Explanation: A disk agitator is a rotating agitator.

7. What is the type1 system for a solution?
a) The solute and solvent are immiscible in all proportions
b) The solute and solvent are miscible in all proportions
c) The concentration of solute is more than solvent
d) The concentration of solvent is more than solute

Answer: b
Explanation: For type1 system, the solute and solvent are miscible in all proportions.

8. What is the type2 system for a solution?
a) The solute and solvent are immiscible in all proportions
b) The solute and solvent are miscible in all proportions
c) The concentration of solute is more than solvent
d) The concentration of solvent is more than solute

Answer: a
Explanation: For type1 system, the solute and solvent are immiscible in all proportions.

9. How is phase equilibrium represented as told by hunter and nash?
a) Square
b) Oval
c) Equilateral triangle
d) Polygon

Answer: c
Explanation: According to hunter-nash method, an equilateral triangle is used to represent phase equilibrium.

10. What is the equilibrium curve in the liquid-liquid equilibrium data also called as?
a) Trinodal curve
b) Cynodal curve
c) Pinodal curve
d) Binodal curve

Answer: d
Explanation: It is called as bimodal curve since it has two nodes.