Mass Transfer (Set 4) 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.
Perforated plate towers are unique for solvent extraction because, they provide
repeated coalescence & redispersion of the drop phase.
In case of absorption & stripping, the interface of the liquid & gas phases are present in equilibrium, when the diffusional resistance of ____ is zero.
interface
Pick out the wrong statement pertaining to the analogy between equations of heat and mass transfer operations.
Reynolds number in mass transfer is analogous to Grashoff number in heat transfer.
The slope of the operating line for a single component co-current absorber when plotted in terms of mole ratio units is
(-) ve
The individual mass transfer co-efficients (moles/m2 . s) for absorption of a solute from a gas mixture into a liquid solvent are, KL = 4.5 and KG = 1.5. The slope of the equilibrium line is 3. Which of the following resistance (s) is (are) controlling?
gas side
Pore size of the molecular seive 5A is ____ mm.
0.5
Swenson-Walker crystalliser is a ____ unit
continuous
According to the Fenske equation, what will be the minimum number of plates required in a distillation column to separate an equimolar binary mixture of components A and B into an overhead fraction containing 99 mol% A and a bottom fraction containing 98 mol% B ? Assume that relative volatility (αAB = 2) does not change appreciably in the coloumn.
12
Absorption (liquid-gas system) with evolution of heat as compared to isothermal absorption results in
all (a), (b) and (c).
With increase in temperature, the mutual solubility of two liquids
increases
Pick out the wrong statement.
The capacity of a distillation coloumn is maximum at total reflux.
The relative volatility of a binary mixture at the azeotropic composition is
1
Relative volatility varies with the concentration of component for an ideal solution. The relative volatity of a binary mixture may be defined as the ratio of vapor pressure of component ‘A’ to that of component ‘B’, when
Vapor phase obeys Dalton’s law and liquid phase obeys Raoult’s law.
Bound moisture is that liquid which exerts an equilibrium vapor pressure ____ that of the pure liquid at the given temperature.
less than
Lewis number (Le) is
Sc / Pr
Which of the following is not a continuous leaching equipment?
Pachuka tank
____ extractor is used for the concentration of radioactive nuclear waste.
Pulsed column
Moisture content of a substance when at equilibrium with a given partial pressure of the vapour is called the ____ moisture.
equilibrium
All moisture in a non-hygroscopic material is the ____ moisture.
unbound
Pick out the correct relationship. (where, Ri = internal reflux ratio Ro = external reflux ratio.)
(1 + Ro) = Ro/Ri
Separation of ____ employs gaseous diffusion process.
isotopes of uranium
For water-ethanol system, the minimum reflux ratio
is computed from the slope of the upper operating line that is tangent to the equilibrium curve.
The interfacial area per unit volume of dispersion, in a gas-liquid contactor, for fractional hold up of gas = 0.1 and gas bubble diameter = 0.5 mm is given by (in m2/m3)
500
Though, theoretically the adsorption & desorption isotherms is expected to coincide but sometimes at least a part of the isotherms does not coincide and this phenomenon is known as adsorption hysterisis. In such cases, the desorption equilibrium pressure is ____ that obtained for adsorption.
lower than