Mass Transfer Questions and Answers Part-16

1. Check whether we get approximately 80% saturation if the total pressure and the partial pressure of the gas mixture is 760 mmHg and 260 mmHg. Also, the vapour pressure is 300 mmHg.
a) true
b) false

Answer: a
Explanation: Percentage saturation is the ratio of absolute molal humidity to the saturated molal humidity. Absolute molal humidity= 260/(760-260. =0.52. Saturated molal humidity= 300/(760-300 =0.652.
%saturation= 0.52/0.652= 79.8(Approximately 80.

2. Gas absorption is the process of transferring solute component from liquid solvent to gas mixture.
a) true
b) false

Answer: b
Explanation: Solute transfer from liquid to gas is known as stripping or desorption. The solute transfer of gas to liquid is known as Absorption.

3. The equilibrium characteristics of the solubility of a gas in liquid helps to determine the
a) Rate
b) Concentration
c) Time
d) No existence of equilibrium characteristics

Answer: a
Explanation: The equilibrium diagram helps to determine the flux with the help of mass transfer co-efficient and concentration gradient.

4. Solubility of a gas increases with increase in temperature.
a) true
b) false

Answer: b
Explanation: As per the equilibrium solubility curve, if the temperature increases partial pressure increases resulting in decreasing solubility.

5. Which of the following is not an example of ideal solution?
a) Solution of benzene in toluene
b) Solution of ethyl and propyl alcohol
c) Paraffin hydrocarbon gas in paraffin oil
d) Solution of isobutane and olefins

Answer: d
Explanation: Only adjacent homologous series falls in ideal solution category. Here, isobutane is an alkane and olefins are alkenes.

6. According to Raoult’s law, for a pure component solution the partial pressure is equals to
a) Total pressure
b) Vapour pressure
c) Atmospheric pressure
d) Mole fraction of respective phase

Answer: b
Explanation: Generally, Raoult’s law states that equilibrium partial pressure of a component at certain conditions equals the product of the mole fraction and the vapour pressure. For a pure component (i.e.) mole fraction equals one.
Therefore, the partial pressure equals vapour pressure.

7. According to Hendry’s law,
a) Y=(p/P)
b) Y=(p* P)
c) p=(Y/P)
d) p=(Y*P)

Answer: a
Explanation: For a straight line Y=m*x, the law proved by Hendry. (i.e.) Y=(y/P) =m*x.
Where, Y=equilibrium mole fraction in vapour
pA= partial pressure
P= Total pressure.

8. Match the following
1) Hendry’s law – a)Ideal solution
2) Dalton’s law – b)Non- Ideal solution
3) Raoult’s law -c)Sum of partial pressure
a) 1- (b), 2-(c),3-(a)
b) 1-(a),2-(b),3-(c)
c) 1-(c),2-(b),3-(a)
d) 1-(a),2-(c),3-(b)

Answer: a
Explanation: Dalton proved a generalized equation states that total pressure is equals to the sum of the partial pressure of the components. Raoult’s law is applicable for only ideal solution since the partial pressure is equals to the product of mole fraction and the vapour pressure.

9. Find the false statement for the better choice of the absorbent.
a) Gas solubility should be high
b) Vapour pressure should be low
c) Viscosity should be high
d) Low freezing point

Answer: b
Explanation: For a better choice of absorbent, the viscosity should be low to get the rapid absorption rates, low pressure drops in absorption tower.

10. Find the most common example for absorption.
a) Ammonia and air in solvent water
b) Ammonia and Carbon dioxide in solvent water
c) Methane and air in solvent water
d) Methane and Carbon dioxide in solvent water

Answer: a
Explanation: Since air won’t dissolve in water the affinity of nitrogen towards the water will be more which converts ammonia into ammonium solution. But in other options, the hydrocarbons easily dissolves in polar solvents.