Separation Processes

SEPARATION

1pt

1 In gas absorption, when the conditions at the bottom of the tower are fixed and the gas flow rate is given, the limiting flow rate based on equilibrium conditions that will require infinitely tall tower is

Select one:

a. minimum liquid flow rate

b. maximum gas flow rate

c. minimum gas flow rate

d. maximum liquid flow rate

Feedback

The correct answer is: maximum liquid flow rate

2 The ease of difficulty of separating components by distillation is determined by the

Select one:

a. relative valatility

b. viscosity

c. weight fraction of the components

d. mole-fraction

Feedback

The correct answer is: relative valatility

3 The rate equation in terms of the gas-phase mass transfer coefficient is used in design calculations instead of that in terms of the liquid phase is when

Select one:

a. the tie line is horizontal

http://www.e-mcl.net/mod/quiz/view.php?id=19848

b. the solubility of the solute in the solvent is very low

c. the controlling resistance is that of the liquid phase

d. the controlling resistance is that of the gas phase

Feedback

The correct answer is: the controlling resistance is that of the gas phase

4 A debutanizer is a

Select one:

a. size reduction equipmant

b. fluid transfer equipment

c. mass transfer equipment

d. heat transfer equipment

Feedback

The correct answer is: mass transfer equipment

5 The mass transfer rate of a material from one phase to another across an interface is increased by

Select one:

a. increassing

b. decreasing the difference between the bulk concentration and the concentration at the interface

between the 2 phases

c. keeping constant

d. making zero

Feedback

The correct answer is: increassing





6 A unit operation in which a soluble component is removed from an inert solid by a solvent which preferentially dissolves the soluble matter from the mixture is known as:

Select one:

a. solvent extraction

b. sedimentation

c. adsorption

d. leaching

Feedback

The correct answer is: adsorption

7 In a vacuum distillation column the vacuum is usually created b y a

Select one:

a. vacuum pump

b. steam ejecctor

c. centrifugal pumpcompressor

Feedback

The correct answer is: vacuum pump

8 In this case a solute in a liquid solution is removed by contacting with another liquid solvent which is relatively immiscible with the solution

Select one:

a. Absorption

b. solid liquid extraction

c. Liquid liquid extraction

Feedback

The correct answer is: Liquid liquid extraction

9 When the relative volatily of 2 miscible are close to 1.00 the components can be separated by

Select one:

a. sedimentation

b. extractive distillation

c. simple fractionation

d. low pressure distillation

Feedback

The correct answer is: extractive distillation

10 To improve the degree of separation of the more volatile component from the less volatile component through distillation the chemical engineer may, without changing the other variables.

Select one:

a. increase the reboiler temperature

b. increase the column pressure

c. reduce the column pressure

d. increase the feed temperature

Feedback

The correct answer is: reduce the column pressure

11 "::SEparation101::The separation of a dilute slurry or suspension by gravity settling into a clear fluid and a slurry of higher solids content is called _____"

Select one:

a. Floatation

b. evaporation

c. sedimentation

d. crystallization

Feedback

The correct answer is: evaporation

12 A membrane separation process where the component from a heated liquid phase permeates through the membrane and is removed under low pressure is

Select one:

a. microfiltration

b. dialysis

c. reverse osmosis

d. pervaporation

Feedback

The correct answer is: reverse osmosis

13 In gas absorption,packings are used

Select one:

a. to reduse the presssure drop created by the following gas

b. to increase the area of the contact between the gas and the liquid

c. to reinforce the absorption tower due to drag created by the liquid and the gas

d. to disseminate the heat generated to maintain isothermal conditions

Feedback

The correct answer is: to increase the area of the contact between the gas and the liquid

14 A binary solution, where A is a low boiler,exhibiting a maximum boiling point, is subjected to flash distillation. If the feed has a concentration in A less than the azeotropic point, the concentration of the distillate will be

Select one:

a. same

b. higher in B

c. higher in A

Feedback

The correct answer is: higher in B

15 The temperature in a distilling column from bottom to top

Select one:

a. increase

b. decrease

c. maximum

d. between maximum and minimum

Feedback

The correct answer is: maximum

16 Increasing the operating pressure of a distillation column

Select one:

a. sharpens separation

b. requires less heat in the feed heater

c. does not make a difference in components separation

d. makes separation difficult

Feedback

The correct answer is: makes separation difficult

17 The degrees of freedom associated with ternary distillation process according to the Gibb's phase rule is

Select one:

a. 5

b. 2

c. 4

d. 3

Feedback

The correct answer is: 3

18 In a distilling column the highest pressure will be at :

Select one:

a. the top

b. the bottom

c. the feed plate

d. between the feed plate and the top

Feedback

The correct answer is: the bottom

19 The pressure drop along a packed tower is

Select one:

a. directly proportional to the square of the mass flow rate

b. inversely proportional to the square of the mass flow rate

c. directly proportional to the mass flow rate

d. inversely proportional to the mass flow rate

Feedback

The correct answer is: directly proportional to the square of the mass flow rate

20 When the liquid flow rate is fixed and the composition of the liquid and the gas at the bottom of the absorption tower are fixed , the limiting flow rate to give infinitely tall tower becomes

Select one:

a. the minimum flow of the rate of the vapor

b. the minimum loading of the liquid

c. the maximum flooding velocity of the vapor

d. the maximum flow of the rate of the vapor

Feedback

The correct answer is: the minimum flow of the rate of the vapor

21 In a gas absorption column the pressure of the lean gas is expected to be

Select one:

a. higher than

b. lower than

c. the same as

d. double the pressure of the rich gas entering the column

Feedback

The correct answer is: lower than

22 It is not very nessesary to correct the rate equation for the phase drift encountered during gas absorption,since the height calculated is

Select one:

a. based on the same percentage recovery anyway

b. based on equimolal counter diffusion anyway

c. slightly under designed anyway

d. slightly over-designed anyway

Feedback

The correct answer is: slightly over-designed anyway

23 In a two-component flash distillation process, when the operating pressure is specified, the concentration of the distillate may be improved in the more volatile component if

Select one:

a. the amount of distillation is increase

b. the operating temperature is decrease

c. none of the above

d. the operating temperature is increase

Feedback

The correct answer is: the operating temperature is decrease

24 When the feed to the column is a saturated liquid,the feed line is

Select one:

a. vertical

b. inclined to the right

c. horizontal

d. inclined to left

Feedback

The correct answer is: vertical

25 Vacuum distillation is resorted to in order to

Select one:

a. use the thinner shell plates for the column

b. reduce the number of trays in the column

c. obtain more bottom products

d. avoid high feed and reboiler temperatures

Feedback

The correct answer is: reduce the number of trays in the column

26 In teaching, the particle size influences the extraction rate. The smaller size,I the greater is the interfacial area between the solid and the liquidII the smaller is the distance the solute must diffuse written the solidIII the lower is the rate of transfer of material

Select one:

a. both I & II

b. both II and III

c. I only

d. II only

Feedback

The correct answer is: both I & II

27 The primary reason why close team is used in an open batch steam distillation is to:

Select one:

a. supply the heat needed by vaporizing liquid

b. increase the operating temperature

c. increase the operating pressure

d. increase the number of degrees of freedom

Feedback

The correct answer is: increase the number of degrees of freedom

28 The recent availability of digital computers resulted in the development of many analytical expressions for the evaluation of K-values.Which of the items below is a source of analitical method for K-values:i.NRTLii.Wilson eqs.iii.UNIQUACivGPA

Select one:

a. iii only

b. I and iv only

c. none among the choices

d. all are sources

Feedback

The correct answer is: all are sources

29 At minimum reflux ratio, the number of plates is

Select one:

a. minimum

b. between minimum and maximum

c. infinite

d. maximum

Feedback

The correct answer is: infinite

30 In the removal of a solute from a water phase by liquid extraction using a membrane, it is advantageous to use

Select one:

a. an assymetric membrane

b. a polymer membrane

c. any porous membrane

d. a hydrophobic membrane

Feedback

The correct answer is: a hydrophobic membrane

31 In a simple batch distillation, the boiling point of the distillate product compared to the residue is

Select one:

a. the same

b. higher

c. lower

Feedback

The correct answer is: lower

32 When the two-film theory is applied to gas absorption, the over-all resistance can be expressed in terms of the individual resistance in the form 1/Ky/a = 1/ky/a+m/kx/a This is possible because of an important assumption.This assumption is

Select one:

a. the tie line has a slope between 0 and 1&

b. the operating line is linear

c. the solute forms an ideal solution with the solvent

d. the slope of the equilibrium curve near the tie line is linear

Feedback

The correct answer is: the slope of the equilibrium curve near the tie line is linear

33 When the relative volatily of 2 miscible are close to 1.00 the components can be separated by

Select one:

a. simple fractionation

b. extractive distillation

c. low pressure distillation

d. sedimentation

Feedback

The correct answer is: extractive distillation

34 The major problem in leaching is to promote diffution of the solute out of the solid and into the liquid.The most effective way of doing this is:

Select one:

a. to reduce the solid to the smallest size feasible

b. to use counter current operation


d. to use cross flow evaporation

Feedback

The correct answer is: to reduce the solid to the smallest size feasible

35 Mc Cabe-Thiele method to determine the theoretical number of stages, may be applied with acceptable results if

Select one:

a. heat losses and heat of solution are very negligiblee

b. the components have high relative volatility

c. the components have different boiling points

d. the system follow Trouton&

Feedback

The correct answer is: the system follow Trouton&

36 In distillation where there are two components and both components are found in both phases,only one variable e.g., liquid p[phase concentration, can be changed independently if the pressure is fixed and temperature and vapor phase concentration will follow. Is this

Select one:

a. FALSE

b. true

Feedback

The correct answer is: true

37 This concerns the removal of a solute such as a salt from a solution by precipitating the solute from the solution

Select one:

a. Diffusion

b. evaporation

c. crystallization

d. drying

Feedback

The correct answer is: crystallization

38In batch open steam distillation, the solution to be open steam distillled should be

Select one:

a. slightly immiscible in water

b. containing large non-volatile impurities

c. completely immiscible in water

d. miscible in water

Feedback

The correct answer is: completely immiscible in water

39 The method of separating a particular gaseous component from a mixture of gases due to their differences in solubility in a liquid phase is

Select one:

a. distillation

b. extraction

c. adsorption

d. absorption

Feedback

The correct answer is: absorption

40 The relative volatility of the mixture at the azeotropic point where the solution exhibits minimum boiling point is

Select one:

a. equal to 1

b. greater than 1

c. less than 1

Feedback

The correct answer is: equal to 1

41

A 50% by weight benzene-toluene mixtures is fed to a column at 180oF and 1 atm. The condition of this feed is

Select one:

a. sub cooled

b. saturated liquid

c. vapor

d. mixture of liquid and vapor

Feedback

The correct answer is: sub cooled

42 This process involves the separation of solute from a fluid by diffusion of this solute from a liquid or gas through a semipermeable membrane barrier to another liquid

Select one:

a. Distillation

b. membrane separation

c. absorption

Feedback

The correct answer is: membrane separation

43 Agitation of the liquid influences the rate of extraction. Agitation osf solvent is important becauseI it prevents sedimentationit increases eddy diffusionIII it increases the transfer of material from the surface of the particles to the bulk of solution

Select one:

a. I only

b. both I and II

c. II only

d. both II and III

Feedback

The correct answer is: both II and III

44 In a simple batch distillation, the boiling point of the distillate product compared to the residue is

Select one:

a. lower

b. higher

c. the same

Feedback

The correct answer is: lower

45 In a gas absorption tower, mass transfer occurs primarily:


Select one:

a. from the gas phase to the packing

b. from the gas phase to the liquid phase

c. from the liquid phase to the gas phase

d. from the liquid phase to the packing

Feedback

The correct answer is: from the liquid phase to the packing

46 When the gas flow rate induces flooding in a packed column gas absober,this is best remedied if the percent recovery of the solute is to be maintained by

Select one:

a. increasing the diameter of the column

b. increasing the height of the column

c. reducing the vapor flow rate

d. reducing the liquid flow rate

Feedback

The correct answer is: increasing the diameter of the column

47 In non-ideal leaching conditions, the tie lines slant to the right indicating that the solute is more highly concentrated in the underflow beacause.

Select one:

a. the solvent and the solute are completely miscible

b. of a partially miscible carrier or incomplete settling

c. all of the choices

d. of equilibrium solubility or f in complete leaching

Feedback

The correct answer is: of equilibrium solubility or f in complete leaching

48 The temperature also affects the rate of extraction. In most cases, the solubility of the material which is being extracted will increase with temperature toI give a higher rate of extractionII increase the diffusion coefficientIII prevention of enzyme action

Select one:

a. I only

b. both II and III

c. II only

d. both I and II

Feedback

The correct answer is: both I and II

48 In a two-component flash distillation process, when the operating pressure is specified, the concentration of the distillate may be improved in the more volatile component if

Select one:

a. the operating temperature is decrease

b. the amount of distillation is increase

c. the operating temperature is increase

d. none of the above

Feedback

The correct answer is: the operating temperature is decrease

49 The temperature of the solution Prob. 2 as distillation progress at constant operating pressure is

Select one:

a. constant

b. increasing

c. decreasing

Feedback

The correct answer is: constant

50 Thera are two underflow-overflow leaching conditions namely ideal and non-ideal.The ideal leaching condition exist if:

Select one:

a. all of the choices are correct

b. sufficient contact time for the solvent to penetrate the solute completely is permitted

c. the carrier solid is completely inert and is not dissolved or entrained in the solvent

d. the solute is infinitely soluble in the soluble

Feedback

The correct answer is: all of the choices are correct

52 In the case of a straight or concave downward operating line and a straight or concave upward equilibrium line, the minimum liquidrate is that at which the

Select one:

a. the operating line just touches the equilibrium line on top of the tower

b. the slope of the operating line is smaller than the equilibrium line

c. the operating line just touches the equilibrium line at the bottom of the tower

d. the operating line intersects the equilibrium line at the middle of the tower

Feedback

The correct answer is: the operating line just touches the equilibrium line at the bottom of the tower

52 In packed columns,the pressure drop for irrigated packing is always greater than the pressure drop for dry packings because

Select one:

a. the surface of dry packing is smoother

b. the flow area of dry packing is greater


d. the drag friction is lesser than the skin friction for dry packing

Feedback

The correct answer is: the flow area of dry packing is greater

53 The difference between stage operation (A) and a continuous phase contact operation (B) is

Select one:

a. that (B) yields discreet concentration changes while (A) yields infinitissimal concentration changes

b. that an ideal (B) yields equilibrium concentration while (A) doaes not

c. that (A) is co-current flow while (B) is counter-current flow

d. that (A) yields discreet concentration changes while (B) yields infinitissimal concentration changes

Feedback

The correct answer is: that (A) yields discreet concentration changes while (B) yields infinitissimal concentration changes

54 Increasing the operating pressure of a distillation column

Select one:

a. makes separation difficult

b. requires less heat in the feed heater

c. sharpens separation

d. does not make a difference in components separation

Feedback

The correct answer is: makes separation difficult

55 The mechanism of mass transfer in a gas absorber is best described by

Select one:

a. Two-film story

b. Surface-Renewal theory

c. the Penetration Theory

d. Chilton-Colburn Analogy

Feedback

The correct answer is: Two-film story

56 In a stripping or desorption operation, the equilibrium curve is

Select one:

a. above the operating line

b. linear

c. below the operating line

d. perpendicular with the tie line


Feedback

The correct answer is: above the operating line

57 Description is another term for

Select one:

a. stripping

b. dephlegmation

c. flash distillation

d. rectification

Feedback

The correct answer is: stripping

58 For an absorber(mass transfer from gas into liquid) the operating lines always

Select one:

a. interest at one&

b. lies above the equilibrium&

45;solubility curve

c. lies below the equilibrium&

d. coincides the equilibrium curve

Feedback

The correct answer is: lies above the equilibrium&

59 The over-all height of a transfer unit based on the gas phase will equal the gas phase individual HTU,Hy/ when

Select one:

a. the gsa phase resistance is very small copmared with the liquid phase


b. the equilibrium curve is lenear

c. the operating line is lenear

d. the liquid&

Feedback

The correct answer is: the liquid&

60 For a mass transfer to take place, there must be

Select one:

a. heat present

b. more than two components involve

c. enthalpy change

d. concentration gradient

Feedback

The correct answer is: concentration gradient

61 The use of a liquid rate far above the minimum value will result in

Select one:

a. none of the choices

b. small number of plates

c. infinite numbers of plate

d. minimum nunber of plates

Feedback

The correct answer is: small number of plates

62 The distribution coefficient of n-hexane at 10 atm abs and 200oC is


Select one:

a. 2&

46;6

b. 1&

c. none

d. 0&

Feedback

The correct answer is: 1&

63 In gas absorption, when the conditions at the bottom of the tower are fixed and the gas flow rate is given, the limiting flow rate based on the equilibrium conditions that will require infinitely tall tower is

Select one:

a. minimum liquid flow rate

b. maximum liquid flow rate

c. minimum gas flow rate

d. maximum flow rate

Feedback

The correct answer is: maximum liquid flow rate

64 The physical separation of component in a miscible mixture by simultaneous evaporation and condensation is

Select one:

a. absorption

b. distillation

c. extraction

d. drying

Feedback

The correct answer is: distillation

65 Open steam binary rectification may be applied with success if the less volatile component is

Select one:

a. water

b. acetone

c. alcohol

d. benzene

Feedback

The correct answer is: water

66 The unit operations bby which the lighter components in a multicomponent solution of volatile liquids are separated from the heavier components is

Select one:

a. absorption

b. drying

c. distillation

Feedback


67 In a membrane separation process, an assymetric membrane refers to

Select one:

a. a membrane that is not uniform in thickness

b. a composite polymer and porous membrane

c. a series of polymer membranes

d. a membrane that is not symmetrical in thickness

Feedback

The correct answer is: a composite polymer and porous membrane

68 A wetted-wall column is usually used to determine mass transfer coefficient experementally because _____ is accurately known.

Select one:

a. concentration gradient of A

b. mass transfer area

c. the flow rate of gas and liquid

d. thickness of the laminar films adjacent to the interface

Feedback

The correct answer is: mass transfer area

69 In the choice of solvent for gas absorption, one of the properties to be consideered is

Select one:

a. solvent should be unusual

b. solvent should have a low vapor pressure

c. solvent should have low boiling point

d. solvent should be highly viscous

Feedback




The correct answer is: solvent should have a low vapor pressure

70 The primary reason why close team is used in an open batch steam distillation is to:

Select one:

a. supply the heat needed by vaporizing liquid

b. increase the number of degrees of freedom

c. increase the operating temperature

d. increase the operating pressure

Feedback

The correct answer is: increase the number of degrees of freedom

71 Using the Antoine equation, the vapor pressure of tetrahydrofuran at 80oC is estimatedto be _____ in torr.

Select one:

a. 1173

b. 2526

c. 1518

d. 2000

Feedback


72 In the distillation the cooled liquid stream returned to the column to cool a plate or stage is called

Select one:

a. reboil

b. feed

c. bottms

d. reflux

Feedback

The correct answer is: reflux

73 For moderately soluble gases with relatively little intersection between the gas and liquid molecules, the law which applies most to establish equilibrium relationship is

Select one:

a. none of the above

b. Henry&

c. Dalton&

d. Raoult&

39;s law

Feedback

The correct answer is: Henry&

74 In an absorption tower packings are placed inside to

Select one:

a. fill up void spaces

b. reduce pressure drop across the tower

c. provide a bigger mass transfer area

d. strengthen ther towert

Feedback

The correct answer is: provide a bigger mass transfer area



75 Tha analogy between mass and heat transfer is complete when

Select one:

a. the momentum transfer rate is negligible

b. the temperature gradient and concentration gradient are equal

c. the resistance to mass and heat transfer are negligible

d. no convictive flux or phase drift involved

Feedback

The correct answer is: no convictive flux or phase drift involved

76 When the molal latent heat of vaporization of the binary system is very much dependent on concentration, the most appropriate method to use to determine the number of idael stage is

Select one:

a. Fenske- Underwood method

b. Mc Cabe-Thiele method

c. Ponchon-Savarit method

d. Lewis-Matheson method

Feedback

The correct answer is: Ponchon-Savarit method

77 A heat transfer equip[ment to convert vapor to liquid is an/a :

Select one:

a. still

b. condenser

c. reboiler





d. evaporator

Feedback

The correct answer is: condenser

78 In the case of a straight or concave downward operating line and a straight or concave upward equilibrium line, the minimum liquidrate is that at which the

Select one:

a. the operating line intersects the equilibrium line at the middle of the tower

b. the operating line just touches the equilibrium line at the bottom of the tower

c. the operating line just touches the equilibrium line on top of the tower

d. the slope of the operating line is smaller than the equilibrium line

Feedback

The correct answer is: the operating line just touches the equilibrium line at the bottom of the tower

79 In mass transfer, a transfer unit means that

Select one:

a. the average driving force is equal to unity

b. the mass transfer coefficient will aprroach unity

c. the concentration range is equal to the average driving force

d. a mole of solute is transferred in aunit height

Feedback

The correct answer is: the concentration range is equal to the average driving force

80 The unit operation by which miscible liquids are separated from one another through heat and mass transfer is

Select one:





a. sedimentation

b. filtration

c. extraction

d. distillation

Feedback


81 In teaching, the particle size influences the extraction rate. The smaller size,I the greater is the interfacial area between the solid and the liquidII the smaller is the distance the solute must diffuse written the solidIII the lower is the rate of transfer of material

Select one:

a. II only

b. both II and III

c. I only

d. both I & II

Feedback

The correct answer is: both I & II

82 It is a unit operation which involves in the mass transfer of soluble materials from the liquid phase to the gseous phase

Select one:

a. drying

b. desorption

c. absorption


d. humidification

Feedback

The correct answer is: desorption

83 A reboiler provides heat to the

Select one:

a. the feed

b. the intermediate reflux

c. top

d. the bottom of a distillation column

Feedback

The correct answer is: the bottom of a distillation column

84

Strictly speaking, the relative volatility of most ideal binary solution is

Select one:

a. not affected by temperaturegreatly affected by temperature

b. greatly affected by temperature

c. slightly affected by temperature

Feedback

The correct answer is: slightly affected by temperature

85 The distillation process involves:

Select one:

a. momentum transfer


b. heat transfer

c. heat and mass transfer

d. mass transfer

Feedback

The correct answer is: heat and mass transfer

3pts

1 Distillation: Minimum number of theoretical trays can be obtained at

Select one:

a. Minimum Reflux

b. Total Reflux

Feedback

The correct answer is: Total Reflux

2 One hundred moles per hour of solution containing 80 moles of A, the rest B is subjected to a simple continuous distillation. D moles of distillate containing 72 moles A is obtained. If A is five times more volatile than B, the concentration of A in the distillate is

Select one:

a. none of these

b. 0.85

c. 0.80

d. 0.533

Feedback

The correct answer is: 0.85





3 Distillation: if the feed is liquid at boiling point the q line is

Select one:

a. 45

b. Horizontal

c. vertical

Feedback

The correct answer is: vertical

4 For gas absorption where no chemical reaction occurs, the height equivalent to a theoretical plate(HETP) for a normal packing size of 50 mm may be estimated to be

Select one:

a. 0.9-1.0m

b. 0.7-0.9 m

c. 0.4-0.5m

d. 0.5-0.7m

Feedback

The correct answer is: 0.7-0.9 m

5 It has been determined that the equivalent HTU and NTU os f a packed absorption tower are 0.85 ft and 15,resfectively. If the same separation can be done in a 10-plate absorption tower,then the HETP isft.

Select one:

a. 12.75none

b. 1.275

c. 0.567

Feedback


6 A liquid mixture containing 45% benzene and 55% toluene by weight is to be fed into a fractionating column at a rate of 5000kg/hr. The feed rate kgmols/hr is

Select one:

a. 58.80lbmols/hr

b. 58.80

c. 28.846

d. 58.74

Feedback


7 If the enthalphy of saturated vapor at 200oF referred to 32oF is 1300 btu/lb while the enthalphy of saturated liquid (Cp1) refered to 0oF is 400 Btu/lb then the latent heat of vaporization of the component at 200oF is

Select one:

a. 400Btu/lb

b. 900Btu/lb

c. 932Btu/lb

d. 868Btu/lb

Feedback

The correct answer is: 868Btu/lb

8 A distillation column with a partial condenser is composed of 7 theoretical stages in the rectifying section and 8 theoretical stages in stripping section. If the overall plate efficiency is 60%, then the actual feed plate is the _____ from the top

Select one:

a. 11th

b. 8th

c. 13th

d. 12th

Feedback

The correct answer is: 11th

9 Distillation: the main assumption in this method is that there must be equimolar overflow through the tower between the feed inlet and the top tray and the feed inlet and bottom tray.

Select one:

a. Ponchon-Savarit

b. McCabe-Thiele

Feedback

The correct answer is: McCabe-Thiele

10 The percentage change in the boiling point of a 20-mole% solution of benzene-toluene solution when the pressure is increased from 1 atm to 2 atm is

Select one:

a. 25.5-%increase

b. 10.5%increase

c. 10.5-% decrease

d. 25.5-% decrease

Feedback

The correct answer is: 25.5-% decrease

11 The pressure drop induce in a packed column containing 1-in naminal size tellerettes for a flow rate of gas of 1500 lb/hr-sq ft and 3000 lb/hr-sq ft of liquid is estimated to be

Select one:

a. 2

b. 0.4

c. 0.7

d. 1.5

Feedback


12 Dimensionless number defined as the ratio of momentum diffusivity and mass diffusivity and is used to characterize fluid flows in which there are simultaneous momentum and mass diffusion -

Select one:

a. schmidt

b. prandtl

c. blot

d. Nusselt

Feedback

The correct answer is: schmidt

13 One hundred moles per hour of solution containing 80 moles of A, the rest B is subjected to a simple continuous distillation. D moles of distillate containing 72 moles A is obtained. If A is five times more volatile than B, the concentration of A in the distillate is

Select one:

a. 0.80

b. 0.85

c. none of these

d. 0.533

Feedback


14 The mole fraction of solute entering a gas absorber is 0.25. If the percentage recovery is 75 percent, then the mole fraction of the solute leaving the tower will be

Select one:

a. 0.0769

b. 0.0833

c. 0.0625

d. 0.157

Feedback


5pts

1 A gas mixture at 1.0 atm pressure abs containing air and CO2 is contacted in a single-stage mixer continuously with pure water at 293K. The two exit gas and liquid streams reach equilibrium. The inlet gas flow rate is 100 kgmol/h, with a mole fraction of CO2 of y-A2=0.20. the liquid flow rate entering is 300 kgmolwater/h. Calculate the amounts and compositions of the two outlet phases(kgmol/h). Assume that water does not vaporize to the gas phase.Henry's law constant at 293 K is 0.142x104atm/mol frac

Select one:

a. 100

b. L-1

c. 200; V-1

d. 150; V-1

e. L-1

f. L-1

g. 250

h. 150

i. L-1

j. 300; V-1

k. 200

l. 250;V-1

Feedback

The correct answer is: L-1

2 Coconot oil is to be produce from dry copra in two stages.First, through expellers to squeeze out part of the coconut oil and then through a counter current multi-stage solvent extraction process. After expelling, the dry copra cake contains 20% residual oil. In the solvent extraction operation, 90% of the rasidual oil in the expeller cake is extracted as a solution containing 50% by weights oil. If fresh solvent is used and one kg of solution with every 2 kg of insoluble coke is removed with underflow, the number of ideal stages required is

Select one:

a. 7

b. 5

c. 4

d. 6

Feedback


3 A liquid mixture containing 45% benzene and 55% toluene by weight is to be fed into a fractionating column at a rate of 5000kg/hr. The feed rate kgmols/hr is

Select one:

a. 58.80lbmols&

b. 28&

46;846

c. 58&

d. 58&

Feedback


4 What will be the concentration of oxygen dissolved in water at 298K when the solution is in equilibrium with air at 1 atm total pressure? The Henry's law constant is 4.38x104atm/mol I) fraction and the partial pressure pAof oxygen in air is 0.21 atm.

Select one:

a. 4.92x10-5

b. 4.8x10-6

c. . 8.4x10-6

d. 9.42x10-4

Feedback

The correct answer is: 4.8x10-6

5 A slurry flaked soybeans weighing 100kg contains 75kg inert solids and 25 kg of solutiuon weight % oil and 90 weight % solvent hexane. This slurry is contacted with 100 kg pure hexane in a signle stage so

that tha value of retention for the outlet underflow is 1.5 kg of insoluble solid per kg solvent in the udhering solution. The compositon of underflow leaving the extraction stage in percent by weight oil is

Select one:

a. 1.5

b. 0.32.3

c. 0.8

Feedback



Select one:

a. 4.92x10-5

b. 4.8x10-6

c. . 8.4x10-6

d. 9.42x10-4

Feedback


7 A slurry flaked soybeans weighing 100kg contains 75kg inert solids and 25 kg of solutiuon weight % oil and 90 weight % solvent hexane. This slurry is contacted with 100 kg pure hexane in a signle stage so that tha value of retention for the outlet underflow is 1.5 kg of insoluble solid per kg solvent in the udhering solution. The compositon of underflow leaving the extraction stage in percent by weight oil is

Select one:

a. 1.5

b. 0.32.3

c. 0.8

Feedback


8 "::SEparation106::The ratio between partial pressure of water vapor in air and the vapor pressure of the water at A the air temperature multiplied by 100 is_____"

Select one:

a. &

37;Saturation

b. &

c. &

d. &

Feedback

The correct answer is: &


Select one:

a. 4.92x10-5

b. . 8.4x10-6

c. 4.8x10-6

d. 9.42x10-4

Feedback


10 Tung meal containing 55% oil is to be extracted at a rate of 4,000 lb per hour using n-hexane containign 5% wt oil as solvent. A countercurrent multiple stage extraction system is to be used. The meal retains 2 lb of solvent per pound of oil free meal while the residual chagre contain 0.11 lb oil per lb oil free meal while the product is compose of 15 wt percent of oil. The theoretical number of ideal stages is?

Select one:

a. 4

b. 3

c. 5

d. 6

Feedback


11 In a salt recovery plant, rock salt is being leached to produce industrial salt in a continuous counter current system consisting of two(2) ideal stages using water as teaching medium. The average composition of the rock salt is : inerts = 70%, soluble salts =25%, moisture =5%, all percentage by weight. The underflow from each stage contains 0.3kg of solution per kg inerts.The plant leaches 50 MT of rock salt per day using 50 MT of water.The quantity of soluble salts recovered in MT/day is

Select one:

a. 14

b. 11&

c. 12&

d. 13&

46;1

Feedback


12 Raw gypsum from a fertilizer plant is being leached out of its salt(NaCl) content is a 2 step continuous counter current system using salt-free water as leaching medium. The underflow, CaSO4/ slurry is then sent to a drier to obtain the final product. The operating data are as follows:Raw gypsum feed = 10 MT/daySalt content of raw gypsum = 1%wtWater feed rate = 90 m3//dayWtaer content of slurry = 0.09 MT H2/O per MT CaSO4/,/br>Based on the forgoing data:The percent of the salt removed in the process is

Select one:

a. 98.9&37;

b. 89.9&37;

c. 95.9&37;

d. 99.9&37;

Feedback

The correct answer is: 99.9&37;

Documents

Separation Processes