Mass Transfer

Experiments were conducted to determine the flux of a species A in a stagnant medium across a gas-liquid interface. The overall mass transfer co-efficient based on the liquid side for dilute systems for the above was estimated to be 4 × 10-3 kg mole/m2.s. The equilibrium data for the system is given as y = 2x. The flux across the interface (in kg mole/m2 .s) for bulk concentrations of A in gas phase and liquid phase as y = 0.4 and x = 0.01 respectively is _________________________?

A. 5.6 × 10-4
B. 8.5 × 10-4
C. 5.6 × 10-3
D. 8.5 × 10-3

H2S is being absorbed in a gas absorber unit. The height of the transfer unit based on the overall mass transfer coefficient on the gas side is 0.4 m. The equilibrium data is given by, y = 1.5 x. The bulk concentration of H2S has to be reduced from 0.05 to 0.001 mole fraction in the gas side. The height of the tower (in meters) corresponding to an operating line given by, y = 5x + 0.001 is ______________________?

A. 2.0
B. 1.56
C. 1.0
D. 0.56

Large scale drying of sugar is done in a _______________ dryer?

A. Spouted bed
B. Tray
C. Rotary
D. Truck

As the reflux ratio, in a continuous counter-current extraction is increased, the number of stages_______________________?

A. Increase
B. Decrease
C. Remain unchanged
D. Can either increase or decrease, depends on the system

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Humidification involves mass transfer between a pure liquid phase and a fixed gas, which is___________________?

A. Insoluble in the liquid
B. Soluble in the liquid
C. Non-ideal in nature
D. At a fixed temperature

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During the constant rate period of drying of a solid ?

A. Increased air humidity decreases the rate of drying
B. Increasing the air temperature decreases the drying rate
C. Surface evaporation of unbound moisture occurs
D. None of these

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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 column ?

A. 5
B. 9
C. 12
D. 28

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