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

1 Answer

Answer :

(C) 12

Related questions

Description : Fenske-Underwood equation used for calculating the minimum number of theoretical plates in distillation column is valid for (A) Constant molal overflow (B) Total reflux (C) Constant relative volatility (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Description : Fenske equation for determining the minimum number of theoretical stages in distillation column holds good, when the (A) Relative volatility is reasonably constant (B) Mixture (to be separated) ... (to be separated) shows positive deviation from ideality (D) Multi-component distillation is involved

Last Answer : (A) Relative volatility is reasonably constant

Description : Pick out the wrong statement. (A) Constant pressure distillation cannot separate an Azeotropic mixture (B) Relative volatility of a binary mixture changes appreciably with the minor change in ... unity (D) Flash distillation is practised on wide spread scale in petroleum refinery

Last Answer : (B) Relative volatility of a binary mixture changes appreciably with the minor change in temperature

Description : Fenske equation determines the (A) Maximum number of ideal plates (B) Height of the distillation column (C) Minimum number of theoretical plates (D) Optimum reflux ratio

Last Answer : (C) Minimum number of theoretical plates

Description : Pick out the wrong statement: (A) Reboiler is not used in open steam distillation (B) The separation of solutes of different molecular sizes in a liquid solution by use of a ... is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition

Last Answer : (D) Fenske-Underwood equation is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition

Description : At __________ reflux, theoretical number of plates in a distillation coloumn is calculated using Fenske-Underwood equation. (A) Operating (B) Total (C) Minimum (D) Maximum permissible

Last Answer : (B) Total

Description : In extractive distillation, solvent is (A) Added to alter the relative volatility of the mixture (B) Of high volatility (C) Present in overhead stream (D) Of high viscosity to give high tray efficiency

Last Answer : (A) Added to alter the relative volatility of the mixture

Description : Pick out the wrong statement. (A) The mole fraction of solute is directly proportional to the molality of a 'dilute' solution (B) For a non-reacting binary mixture of ideal gases, the partial ... at all temperature (D) The relative volatility of a binary mixture at the Azeotropic composition is 1

Last Answer : (C) Azeotropes obey Raoult's law at all temperature

Description : Pick out the wrong statement. (A) With decrease in feed temperature, the number of plates required for binary distillation decreases for a given L/V' ratio (B) The extraction per unit ... and its cross￾section is wider at the bottom (D) Vander wall adsorption is also called chemisorption

Last Answer : (D) Vander wall adsorption is also called chemisorption

Description : The-relative volatility for separation of a non-ideal binary mixture by distillation should be (A) 0 (B) 1 (C) > 1 (D) < 1

Last Answer : (C) > 1

Description : For a binary mixture with low relative volatility, (A) Use steam distillation (B) Use molecular distillation (C) Use high pressure distillation (D) An azeotrope may be formed during distillation

Last Answer : (D) An azeotrope may be formed during distillation

Description : For a binary mixture with low relative volatility, continuous rectification to get pure products will require (A) Low reflux ratio (B) Less number of trays (C) Small cross-section column (D) High reflux ratio

Last Answer : (D) High reflux ratio

Description : Pick out the correct statement. (A) Ponchan-Savarit method is more accurate than McCabe-Thiele method to determine the number of theoretical stages required for the separation of ... Flash distillation is suitable for separating components which have very close boiling temperature

Last Answer : (A) Ponchan-Savarit method is more accurate than McCabe-Thiele method to determine the number of theoretical stages required for the separation of non￾ideal binary system by distillation

Description : Relative volatility does not change appreciably with the change in (A) Temperature (B) Vapour pressure of either component (C) Total pressure (D) None of these

Last Answer : (A) Temperature

Description : Pick out the correct statement. (A) Higher hold up of the solid in the rotary dryer results in better exposure of the solids to the gas (B) The 'Hatta number' is ... reflux in case of distillation operation requires infinite number of plates for a binary system separation

Last Answer : (C) For a non-reacting binary mixture of ideal gases, the partial pressure distribution of both components is linear in the case of steady state equimolal counter-diffusion

Description : Pick out the wrong statement. (A) The Reynolds analogy for mass transfer is given by Lewis relation and is applicable, when Schmidt number is one (B) Sherwood number for flow in pipes can be expressed ... flux of a component A in binary mixture of A and B is given by - Dab'.dCA/dz

Last Answer : (C) According to film theory for equimolar counter diffusion, the mass transfer coefficient is given by DAB(B)P - 3, Q - 2

Description : A distillation column with N plates is being operated under normal conditions. At some point of time, the operation is shifted to total reflux condition (i.e., no product and residue are ... and without total reflux (D) The top and bottom compositions correspond to the maximum enrichment available

Last Answer : (D) The top and bottom compositions correspond to the maximum enrichment available

Description : High pressure at the bottom of a distillation tower handling heat sensitive materials results in (A) Thermal decomposition of bottoms (B) Increased relative volatility (C) Erosion of the tower (D) Very efficient operation

Last Answer : (A) Thermal decomposition of bottoms

Description : Solvent used in extractive distillation (A) Changes the relative volatility of the original components (B) Should be of high volatility (C) Should form azeotropes with the original components (D) All (A), (B) and (C)

Last Answer : (A) Changes the relative volatility of the original components

Description : Solvent used in extractive distillation (A) Is of low volatility (B) Forms a low boiling azeotrope (C) Forms a high boiling azeotrope (D) Does not alter the relative volatility of the original components

Last Answer : (B) Forms a low boiling azeotrope

Description : Entrainer used in Azeotropic distillation should (A) Form a low boiling azeotrope with one of the constituents of the mixture (B) Form a new azeotrope of low relative volatility with one of the ... (C) Have high latent heat of vaporisation (D) Have high viscosity to provide high tray efficiency

Last Answer : (A) Form a low boiling azeotrope with one of the constituents of the mixture

Description : In case of __________ distillation, a solvent is added to alter the relative volatility of the mixture to be separated. (A) Molecular (B) Azeotropic (C) Extractive

Last Answer : (C) Extractive

Description : The minimum number of theoretical plates is required for achieving a given separation in distillation column with (A) No reflux (B) Total reflux (C) Zero reflux ratio (D) Minimum reflux ratio

Last Answer : (B) Total reflux

Description : For a distillation column operating at minimum reflux, the (A) Concentration of liquid and vapour leaving a plate will be same (B) Reflux ratio will be maximum (C) Number of plates required will be maximum

Last Answer : (C) Number of plates required will be maximum

Description : Relative volatility varies with the concentration of component for an ideal solution. The relative volatility of a binary mixture may be defined as the ratio of vapor pressure of component 'A' to that of ... law (D) Vapor phase obeys Dalton's law and liquid phase obeys Raoult's law

Last Answer : (D) Vapor phase obeys Dalton's law and liquid phase obeys Raoult's law

Description : The relative volatility of a binary mixture at the Azeotropic composition is (A) 1 (B) > 1 (C) 0 (D) ∞

Last Answer : (D) ∞

Description : The relative volatility of a binary mixture at constant temperature __________ the total pressure. (A) Decreases with increase in (B) Increases with increase in (C) Is independent of (D) None of these

Last Answer : (A) Decreases with increase in

Description : Pick out the correct statement. (A) The slope of the stripping line is always less than unity (B) For a given separation in a binary distillation column, with increase in reflux ratio ( ... (D) Kremser-Brown-Souder's equation is used to calculate the efficiency of a plate tower

Last Answer : C) In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux

Description : McCabe-Thiele method of binary distillation does not assume that the (A) Sensible heat changes are negligible compared with latent heat changes (B) Molar latent heats of all components are equal (C) Heat of mixing is negligible (D) None of these

Last Answer : (D) None of these

Description : The theoretical minimum work required to separate one mole of a liquid mixture at 1 atm, containing 50 mole % each of n- heptane and n octane into pure compounds each at 1 atm is (A) -2 RT ln 0.5 (B) -RT ln 0.5 (C) 0.5 RT (D) 2 RT

Last Answer : (B) -RT ln 0.5

Description : As the reflux ratio in a distillation column is increased from the minimum, the (A) Slope of the operating line in stripping section decreases (B) Number of plates decreases very slowly first ... decreases and then increases (D) Liquid flow increases while the vapor flow decreases for a system

Last Answer : (C) Total cost first decreases and then increases

Description : At what value of reflux ratio, number of theoretical plates in a distillation column is minimum? (A) 0 (B) 1 (C) ∞ (D) < 1

Last Answer : (C) ∞

Description : Components, having widely different boiling point in a binary mixture, can be separated using __________ distillation. (A) Molecular (B) Extractive (C) Steam (D) Simple

Last Answer : (D) Simple

Description : If the amount of the steam used in steam distillation is increased, the temperature of distillation (A) Increases (B) Decreases (C) Remains unchanged (D) Depends on relative volatility

Last Answer : (B) Decreases

Description : Separation of two volatile liquids by distillation makes use of their (A) Selectivity (B) Relative volatility (C) Solubility (D) Density difference

Last Answer : (B) Relative volatility

Description : In a binary system, separation is very efficient, when the relative volatility is (A) 1 (B) > 1 (C) < 1 (D) 0.5

Last Answer : (B) > 1

Description : Given the following data pairs (x, y), find the regression equation. (1, 1.24), (2, 5.23), (3, 7.24), (4, 7.60), (5, 9.97), (6, 14.31), (7, 13.99), (8, 14.88), (9, 18.04), (10, 20.70) a. y = 0.490 x - 0.053 b. y = 2.04 x c. y = 1.98 x + 0.436 d. y = 0.49 x

Last Answer : c. y = 1.98 x + 0.436

Description : With increase in pressure, the relative volatility for a binary system (A) Increases (B) Decreases (C) Remains same

Last Answer : (B) Decreases

Description : When the liquid phase and vapour phase of a binary system obeys Raoult's and Dalton's law respectively, the relative volatility is the ratio of (A) Vapour pressure of component A to that of ... to the partial pressure of A (D) Partial pressure of component A to the total pressure

Last Answer : (A) Vapour pressure of component A to that of component B

Description : The reflux to a distillation column is 100 moles/hr, when the overhead product rate is 50 moles/hr. The reflux ratio is (A) 2 (B) 0.5 (C) 50 (D) 150

Last Answer : (A) 2

Description : In distillation, overhead product contains (A) Only one component (B) Two components (C) Any number of components (D) Only saturated liquid

Last Answer : (C) Any number of components

Description : Separation of a mixture of two gases by absorption in the liquid solvent depends upon the difference in their (A) Viscosity (B) Density (C) Solubility (D) Relative volatility

Last Answer : (C) Solubility

Description : Fugacity is a measure of the (A) Escaping tendencies of the same substance in different phases of a system (B) Relative volatility of a mixture of two miscible liquids (C) Behaviour of ideal gases (D) None of these

Last Answer : (A) Escaping tendencies of the same substance in different phases of a system

Description : What laboratory procedure you would use to separate and recover the components of a mixture containing BaSO4 Na2CO3 and C10H8?

Last Answer : Na2CO3 is soluble in water and separated by filtration from a water mixture.Naphtalene is separated by heating when sublimation occur.

Description : Overall efficiency of the distillation column is (A) The ratio of number of ideal plates to actual plates (B) The ratio of number of actual plates to ideal plates (C) Same as the Murphree efficiency (D) Always more than the point efficiency

Last Answer : (A) The ratio of number of ideal plates to actual plates

Description : . For the same feed, feed quality and separation (in a distillation column), with the increase of total pressure, the number of ideal plates will (A) Increase (B) Decrease (C) Remain same (D) Data insufficient, can't be predicted

Last Answer : (A) Increase

Description : Component A is diffusing in a medium B. The flux NA relative to a stationary point is equal to the flux due to molecular diffusion, if (A) Mass transfer is accompanied by reaction (B ... stagnant medium B (C) Molecular mean free path is high (D) There is equimolar counter diffusion

Last Answer : (D) There is equimolar counter diffusion

Description : In a binary distillation column, if the feed contains 40 mole % vapour, the q line will have a slope of (A) 1.5 (B) -0.6 (C) -1.5 (D) 0.6

Last Answer : (C) -1.5

Description : For a binary mixture distillation process, the degree of freedom is 2. However, if the pressure is fixed in this process, the number of independent variables in this process will be (A) 1 (B) 0 (C) 2 (D) 3

Last Answer : (A) 1