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SEPPROC Flashcards

1
Q

Which of the following solutions will follow Raoult’s law most closely?

A

A solution of benzene, toluene and oxylene.

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2
Q

Boiling point diagram is

A

affected by pressure

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3
Q

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

A

relative volatility

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4
Q

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

A

greatly affected by temperature

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5
Q

When the relative volatility of two miscible components is close to 1.00, the components can be separated by

A

extractive distillation

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6
Q

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

A

distillation

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7
Q

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

A

lower

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8
Q

Increasing the operating pressure of a distilling column

A

makes separation difficult

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9
Q

One mole feed of a binary mixture of a given composition is flash vaporized at a fixed P and T. If Raoult’s law is obeyed, then changing the feed composition would effect

A

the fraction vaporized but not the product composition

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10
Q

Steam distillation is used to

A

avoid thermal decomposition of a component.

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11
Q

The amount of steam required per unit quantity of distillate in case of steam distillation will be reduced by

A

raising the temperature and lowering the total pressure

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12
Q

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

A

reflux

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13
Q

In a distilling column, the highest pressure will be at

A

the bottom

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14
Q

A heat transfer equipment to convert vapor to liquid is a/an

A

condenser

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15
Q

A reboiler provides heat to the

A

the bottom of a distilling column

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16
Q

The temperature in distilling column, from bottom to top

A

decreases

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17
Q

The theoretical minimum reflux ratio in distillation column is attained if the column has

A

infinite number of plates

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18
Q

If x co-ordinate of intersection point of feed line and rectifying sections operating line on equilibrium curve is same as the mole fraction of more volatile components in the feed, then the quality of feed is

A

saturated liquid

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19
Q

As the reflux ratio decreases, the

A

number of plates increases

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20
Q

In a distillation column, with increase in the reflux ratio, the heat removed in the cooler

A

increases

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21
Q

Fenske’s equation for determining the minimum number of theoretical stages in distillation column holds good, when the

A

relative volatility is reasonably constant

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22
Q

Inside the distillation column, the

A

driving force for the vapor flow is the pressure drop

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23
Q

On moving the feed line (q-line) from saturated liquid feed (vertical position) to saturated vapor feed (horizontal feed), if the slope of both the operating lines are to be increased, then it will result in

A

increased reflux ratio

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24
Q

In case of binary distillation, increasing the reflux ratio above optimum does not result in the increase of

A

area between operating line and 45° diagonal x-y diagram

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25
Q

Overall efficiency of the distillation column is

A

the ratio of number of ideal plates to actual plates

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26
Q

Pick out the correct statement.
a. Ponchon-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.
b. A sharp decrease in pressure drop is an indication of flooding in a distillation column.
c. Solvent used in extractive distillation should be of high volatility.
d. Flash distillation is suitable for separating components which have very close boiling temperature.

A

Ponchon-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.

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27
Q

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 (above the minimum reflux ratio), the fixed cost of the distillation column first increases and then decreases. c. In Ponchon-Savarit method of no. of theoretical plate determination, the stripping and rectifying operating lines are vertical at total reflux.
d. Kremsor-Brown-Souder’s equation is used to calculate the efficiency of a plate tower.

A

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

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28
Q

Design calculation for multiple component distillation is done by

A

tray to tray calculations

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29
Q

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 suitable membrane is called dialysis.
c. Freeze drying is used for the drying of fish.
d. Fenske-Underwood equation is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition.

A

Fenske-Underwood equation is used for calculating theoretical number of plates in a distillation column at normal operating reflux condition

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30
Q

In extractive distillation, solvent is

A

added to alter the relative volatility of the mixture

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31
Q

Solvent used in extractive distillation

A

forms a low boiling azeotrope

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32
Q

Pick out the wrong statement.
a. Critical moisture content is not a property of the material itself. b. A sharp increase in pressure drop gives an indication of the flooding in a distillation column.
c. Separation of components is not possible in liquid extraction, if selectivity is unity.
d. Dehydration of ethyl alcohol is most economically done by molecular distillation at very high vacuum.

A

Dehydration of ethyl alcohol is most economically done by molecular distillation at very high vacuum

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33
Q

Azeotropic distillation is employed to separate

A

constant boiling mixture

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34
Q

The equilibrium liquid composition compared to the vapor composition in case of azeotropic mixture is

A

same

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35
Q

The equilibrium liquid composition compared to the vapor composition in case of azeotropic mixture is

A

same

36
Q

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 pressure distribution of both components is nonlinear in the case of steady state unimolal unidirectional diffusion.
c. Azeotropes obey Raoult’s law at all temperature.
d. The relative volatility of a binary mixture at the azeotropic composition is 1.

A

Azeotropes obey Raoult’s law at all temperature.

37
Q

Pick out the system with minimum boiling azeotrope at 1 atm.

A

ethyl alcohol-water

38
Q

Which of the following binary systems is an example of a maximum boiling azeotrope?

A

water-hydrochloric acid

39
Q

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

A

leaching

40
Q

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

A

leaching

41
Q

The unit operation by which soluble components of a liquid mixture are dissolved in a liquid immiscible with the insoluble component is

A

solvent extraction

42
Q

Tea percolation employs

A

leaching

43
Q

Which of the following is the most commonly used leaching solvent in vegetable oil industry?

A

hexane

44
Q

Leaching of sugar from sugar beets is done using

A

hot water

45
Q

In a counter-current extractor, as the axial mixing increases, the extraction efficiency

A

decreases

46
Q

Bollman extractor

A

is used for extraction of oil from oilseed

47
Q

Acetic acid will be most economically separated from a dilute solution of acetic acid in water by

A

solvent extraction

48
Q

Liquid-liquid extraction is based on the differences in

A

solubility

49
Q

Radioactive nuclear waste is treated in

A

pulsed column extractor

50
Q

The solvent used in liquid extraction should not have high latent heat of vaporization, because

A

the pressure drop and hence the pumping cost will be very high.

51
Q

Solvent extraction is the terminology applied to the liquid-liquid extraction, which is preferred for the separation of the components of liquids, when

A

extracting solvent is cheaply & abundantly available.

52
Q

In a counter-current liquid extractor

A

only one of the liquids may be pumped at any desired rate.

53
Q

A coalescer in a mixer-settler liquid-liquid extraction column

A

all of these

54
Q

Antibiotics are best handled in a

A

pulsed column extractor

55
Q

Rose oil is extracted from rose leaves using distillation

A

steam distillation

56
Q

When the solvent dissolves very little of solute then

A

large quantity of solvent is required to extract the solute

57
Q

An ideal single stage extraction process is used to treat 100 mol/s of an organic feed solution. The solute concentration in this solution is to be reduced from 0.5 mol% to 0.1 mol%. A pure solvent S is used. To reduce the solvent requirement by half for the same separation

A

use another pure solvent S* whose partition coefficient is twice that of S

58
Q

The triangle whose one corner coincides with the enriching line and the outer corner is on the stripping line is called the

A

feed plate

59
Q

Flash distillation is suitable for the separation of components

A

having very wide boiling points.

60
Q

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

A

vapor phase obeys Dalton’s law and liquid phase obeys Raoult’s law.

61
Q

Leaching of coarse solid lumps is also termed as

A

percolation

62
Q

In an operating distillation column, the

A

driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column.

62
Q

Large scale usage of flash distillation is practiced in

A

petroleum refinning

63
Q

In case of steam distillation, the steam leaving the liquid is not completely saturated with distillate vapor, because

A

mixing of steam with the material being vaporised is not so intimate as to result in equilibrium condition.

64
Q

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

65
Q

Which of the following is the most suitable for extraction in a system having very low density difference ?

A

Centrifugal extractor

66
Q

Total reflux in a distillation operation requires minimum

A

number of plates

67
Q

In batch distillation with constant reflux, overhead product composition __ with time.

A

decreases

68
Q

Raoult’s law applies to the

A

solvents

69
Q

In distillation, overhead product contains

A

any number of components

70
Q

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

71
Q

The operation involved when the soluble material is largely on the surface of an insoluble solid and is merely washed off by the solvent is called

A

elutriation or elution

72
Q

Pick out the wrong statement.
a. Heat removal load on cooler remains constant, even with increase of the reflux ratio in a distillation column.
b. Different solids have different equilibrium moisture curves.
c. Total condenser or reboiler is considered equivalent to one theoretical plate in McCabe-Thiele method of theoretical plate calculation for distillation column.
d. Even a forced draft cooling tower can not cool water below the wet bulb temperature.

A

Heat removal load on cooler remains constant, even with increase of the reflux ratio in a distillation column.

73
Q

An aqueous solution of methanol is to be distilled in a tray column. High pressure steam is available as a source of heat. For a given reflux ratio and overhead composition, two options are being explored; (i) a reboiler is used and (ii) no reboiler is used but steam is fed directly to the bottom of the column. As compared to option (i), in option (ii)

A

less number of trays are required.

74
Q

Ponchan-Savarit method analyses the fractional equipment based on

A

both enthalpy and material balances.

75
Q

When the mixture to be distilled has a very high boiling point and the product material is heat sensitive, the separation technique to be used is __ distillation.

A

steam

76
Q

The fixed cost of a distillation column at minimum reflux ratio is

A

infinite

77
Q

__ extractor uses centrifugal force for separating the two phases.

A

Podbielniak

78
Q

In most of the mechanically agitated liquid-liquid extractors, baffles or horizontal compartmental plates are provided, which helps in

A

All of these (maintaining the concentration difference between the two phases, increasing the rate of extraction, reducing the axial mixing)

79
Q

Which of the following applies to a feed at dew point?

A

f = 1

80
Q

Pick out the wrong statement.
a. With increase in pressure, the solubility of gases in solvent increases at a fixed temperature.
b. The capacity of a distillation column is maximum at total reflux.
c. In solvent extraction, the distribution coefficient should be as large as possible for solvent economy.
d. Decrease in Murphree plate efficiency is an indication of entrainment in distillation column.

A

The capacity of a distillation column is maximum at total reflux.

81
Q

The relative volatility of a binary mixture at the azeotropic composition is

A

1

82
Q

Which of the following is not a continuous leaching equipment?

A

Pachuka tank

83
Q

High pressure at the bottom of a distillation tower handling heat sensitive materials results in

A

thermal decomposition of bottoms.

84
Q

For a binary mixture with low relative volatility, continuous rectification to get pure products will require

A

high reflux ratio

85
Q

In steam distillation, the

A

product must be immiscible with water.

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