IndiaBIX Chemical Engineering: Mass Transfer Section 8 Flashcards
__________ is used as an ‘entrainer’ for the separation of acetic acid-water mixture by distillation.
Furfural
Benzol
Butyl acetate
Hexane
Butyl acetate
Rotary dryers cannot handle __________ materials.
free flowing
dry
sticky
grannular
sticky
Pick out the correct statement.
Diffusivity decreases with increase in temperature.
Diffusivity increases with increase in molecular weight.
Diffusivity increases with the size of the individual molecule.
none of these.
none of these.
An example of elutioh is
separation of uranium oxide from its ore by H2SO4 in a Pachuca tank.
separation of sugar from sugar beet by hot water.
dissolution of tannin out of tree barks by water.
recovery of vegetable oils from seeds.
separation of uranium oxide from its ore by H
The operating line for an absorber is curved, when plotted in terms of
mole fractions
mole ratios
partial pressure
mass fractions
partial pressure
Relative volatility does not change appreciably with the change in
temperature
vapour pressure of either component
total pressure
none of these
temperature
Boiling point diagram is not affected by the ambient
pressure
humidity
temperature
both (b) and (c)
both (b) and (c)
The dew point of a saturated gas phase equals the __________ temperature.
gas
room
wet bulb
none of these
gas
A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process ?
Flow rate of inlet air
Relative humidity of outlet air
Humidity of inlet air
Temperature of the solid
Temperature of the solid
In case of liquid-liquid binary diffusion, diffusivity of one constituent into another is not dependent on the
temperature and pressure
concentration
nature of the constituents
none of these
none of these
For continuous drying of grannular or crystalline material, the dryer used is the __________ dryer.
tunnel
tray
rotary
none of these
rotary
When adsorption hysteresis is observed, the desorption equilibrium pressure is __________ that obtained by adsorption.
always lower than
always higher than
same as
dependent on the system; can be either lower or higher than
always lower than
Moisture in a substance exerting an equilibrium vapour pressure less than that of pure liquid at the same temperature is called the __________ moisture.
bound
unbound
critical
none of these
bound
For a binary mixture with low relative volatility, continuous rectification to get pure products will require
low reflux ratio
less number of trays
small cross-section column
high reflux ratio
high reflux ratio
The efficiency of a plate column will be maximum, when the flow is ideal __________ the plate.
across
above
both (a) & (b)
neither (a) nor (b)
both (a) & (b)
Heat load in a cooling tower
means the amount of heat thrown away (KCal/hr.) by the cooling tower.
is equal to the number of kg, of water circulated times the cooling range.
both (a) & (b).
neither (a) nor (b).
both (a) & (b).
In case of absorption with exothermic reaction, for fluids having
Pr = Sc; percentage change in heat and mass transfer flux will be the same for a given change in the degree of turbulence.
Pr = Sc = 1; total mass, momentum and thermal diffusivity will be the same.
both (a) and (b)
Pr = Sc ; there won’t be any change in heat and mass transfer flux with changes in degree of turbulence.
both (a) and (b)
Detergent solution is dried to a powder in a
spray dryer
spouted bed dryer
tunnel dryer
pan open to atmosphere
spray dryer
Which of the following mixtures does not form an azeotrope at atmosheric pressure?
Water-alcohol
Methyl alcohol-acetone
Butyl acetate-water
None of these
None of these
During bottling of cold drinks (e.g. Pepsi), the main resistance to mass transfer for the absorption of carbon dioxide in water lies in the
gas film
liquid film
liquid-gas interface
none of these
liquid film