Mass Transfer (Set 6) Flashcards
As one of the transport phenomena, the concepts in mass transfer are crucial for design, operation, and maintenance of mass or heat & mass transfer equipment such as mixing and separation processes.
In a binary system, separation is very efficient, when the relative volatility is
> 1
Fenske-Underwood equation used for calculating the minimum number of theoretical plates in distillation column is valid for
all (a), (b) and (c)
The binary diffusivity in gases does not depend upon the
none of these
Not pressure, temperature, and nature of components
Berl saddle made of carbon cannot be used for
oxidising atmosphere
1 kg of a saturated aqueous solution of a highly soluble component A at 60°C is cooled to 25°C. The solubility limits of A are (0.6 kgA/kg water) at 60°C and (0.2 kgA/kg water) at 25°C. The amount in kg of the crystals formed is
0.2
During drying of a solid, the critical moisture content increases with
a. decreased drying rate
b. increased thickness of the solid
c. increased drying rate
d. both (b) and (c).
both (b) and (c).
Priming in a distillation column
is characterised by the presence of foam throughout the space between trays.
The commonly used solvent in supercritical extraction is
carbon dioxide.
When the liquid over a plate is of uniform concentration, then
Murphree efficiency = point efficiency.
In saturated gas, the
vapour is in equilibrium with the liquid at the gas temperature.
As per Gilliland’s equation, the diffusivity is
all ‘a’, ‘b’ & ‘c’.
Pick out the wrong statement.
The operating line lies above the equilibrium curve in case of a gas desorber.
A mixture of 10% C6H6 vapour in air at 25°C and 750 mm Hg has a dew point of 20°C. Its dew point at 30°C and 700 mm Hg will be around ____ °C.
18.7
Which of the following is not fixed by the process requirements, in the design of absorbers?
None of these.
If the amount of the steam used in steam distillation is increased, the temperature of distillation
decreases
Moisture in a solid exerting an equilibrium vapour pressure equal to that of the pure liquid at the same temperature is called the ____ moisture.
unbound
Inside the distillation columns, the
driving force for the liquid flow is its weight.
When the psychometric ratio is ____ then the adiabatic saturation temperature and wet bulb temperature becomes equal.
1
Desirable value of absorption factor in an absorber is
> 1
Refractory bricks are usually dried in a ____ dryer.
tunnel
For ____ drying, the effects of velocity, temperature and humidity of the gas and the thickness of the solid are the same.
both (a) and (b)
What is the degree of freedom of an absorption process in which only one component is transferred between phases?
3
Sticky material can be dried in a ____ dryer.
tray
Langmuir equation is associated with
adsorption
During the constant rate period of drying of a solid,
surface evaporation of unbound moisture occurs.
At a fixed total pressure, humidity depends only on the
partial pressure of vapour in the mixture.
If moisture content of solid on dry basis is X, then the same on wet basis is
X/X+1
Flash distillation is
used for multicomponent systems like crude refining.
____ developed the film theory.
Higbie
For absorbers, high pressure drop results in
high operating cost.
Which of the following parameters remains almost constant during adiabatic saturation of unsaturated air?
Wet bulb temperature
Coffee is prepared from coffee beans by leaching with
hot water
Gaseous diffusion co-efficient increases with increase in the
temperature
With increase in absolute humidity, the dew point of an unsaturated mixture of air and water vapor (at constant pressure and temperature)
increases
If xD = overhead product molal composition and RD = reflux ratio, then slope and intercept of the operating line for rectifying section are respectively
https://www.indiabix.com/_files/images/chemical-engineering/mass-transfer/287-102-2.png
Pick out the wrong statement. Raoult’s law does not apply, when the
component molecules are nonpolar.
Water-ethyl alcohal solution can be concentrated (in respect of alcohal concentration) by ____ distillation.
vacuum
L/mG is the expression for
absorption factor
Extraction of pencillin employs a ____ extraction coloumn.
centrifugal
In case of gases, the binary diffusivity is proportional to (where, P = pressure)
1/P