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CHEMICAL ENGINEERING

At equilibrium the concentration of water in vapour phase (C*)in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C* = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is

CHEMICAL ENGINEERING, Mass Transfer /
Question: At equilibrium the concentration of water in vapour phase (C*)in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C* = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is
[A].

0.0

[B].

0.2

[C].

0.4

[D].

1.0

Answer: Option C

Explanation:

No answer description available for this question.

At equilibrium the concentration of water in vapour phase (C*)in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C* = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is Read More »

CHEMICAL ENGINEERING, Mass Transfer

A 25 cm x 25 cm x 1 cm flat sheet weighing 1.2 kg initially was dried from both sides under constant drying rate conditions. It took 1500 seconds for the weight of the sheet to reduce to 1.05 kg. Another 1m x 1m x 1cm flat sheet of the same material is to be dried from one side only.Under the same constant drying rate conditions, the time required for drying (in seconds) from its initial weight of 19.2 kg to 17.6 kg is

CHEMICAL ENGINEERING, Mass Transfer /
Question: A 25 cm x 25 cm x 1 cm flat sheet weighing 1.2 kg initially was dried from both sides under constant drying rate conditions. It took 1500 seconds for the weight of the sheet to reduce to 1.05 kg. Another 1m x 1m x 1cm flat sheet of the same material is to be dried from one side only.Under the same constant drying rate conditions, the time required for drying (in seconds) from its initial weight of 19.2 kg to 17.6 kg is
[A].

1000

[B].

1500

[C].

2000

[D].

2500

Answer: Option A

Explanation:

No answer description available for this question.

A 25 cm x 25 cm x 1 cm flat sheet weighing 1.2 kg initially was dried from both sides under constant drying rate conditions. It took 1500 seconds for the weight of the sheet to reduce to 1.05 kg. Another 1m x 1m x 1cm flat sheet of the same material is to be dried from one side only.Under the same constant drying rate conditions, the time required for drying (in seconds) from its initial weight of 19.2 kg to 17.6 kg is Read More »

CHEMICAL ENGINEERING, Mass Transfer

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)

CHEMICAL ENGINEERING, Mass Transfer /
Question: 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.

[B].

composition of the residue remains unchanged.

[C].

more number of trays are required but the residue composition remains unchanged.

[D].

more number of trays are required and the residue composition is more dilute in methanol.

Answer: Option A

Explanation:

No answer description available for this question.

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) Read More »

CHEMICAL ENGINEERING, Mass Transfer

For water-ethanol system, the minimum reflux ratio

CHEMICAL ENGINEERING, Mass Transfer /
Question: For water-ethanol system, the minimum reflux ratio
[A].

is computed from the slope of the upper operating line that is tangent to the equilibrium curve.

[B].

is computed from the intercept of the operating line.

[C].

cannot be computed.

[D].

is the optimum reflux ratio.

Answer: Option A

Explanation:

No answer description available for this question.

For water-ethanol system, the minimum reflux ratio Read More »

CHEMICAL ENGINEERING, Mass Transfer

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 being withdrawn and feed to the column is stopped). At the new steady state,

CHEMICAL ENGINEERING, Mass Transfer /
Question: 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 being withdrawn and feed to the column is stopped). At the new steady state,
[A].

composition of vapors and that of liquid do not vary throughout the column.

[B].

reboiler load and condenser load are minimum.

[C].

the top and bottom compositions are unchanged with and without total reflux.

[D].

the top and bottom compositions correspond to the maximum enrichment available.

Answer: Option D

Explanation:

No answer description available for this question.

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 being withdrawn and feed to the column is stopped). At the new steady state, Read More »

CHEMICAL ENGINEERING, Mass Transfer

In a liquid-liquid extraction, 10 kg of a solution containing 2 kg of solute C and 8 kg of solvent A is brought into contact with 10 kg of solvent B. Solvent A and B are completely immiscible in each other whereas solute C is soluble in both the solvents. The extraction process attains equilibrium. The equilibrium relationship between the two phases is Y* = 0.9X, where Y* is the kg of C/kg of B and X is kg of C/kg of A. Choose the correct answer.

CHEMICAL ENGINEERING, Mass Transfer /
Question: In a liquid-liquid extraction, 10 kg of a solution containing 2 kg of solute C and 8 kg of solvent A is brought into contact with 10 kg of solvent B. Solvent A and B are completely immiscible in each other whereas solute C is soluble in both the solvents. The extraction process attains equilibrium. The equilibrium relationship between the two phases is Y* = 0.9X, where Y* is the kg of C/kg of B and X is kg of C/kg of A. Choose the correct answer.
[A].

The entire amount of C is transferred to solvent B.

[B].

Less than 2 kg but more than 1 kg of C is transferred to solvent B.

[C].

Less than 1 kg of C is transferred to B.

[D].

No amount of C is tranferred to B.

Answer: Option A

Explanation:

No answer description available for this question.

In a liquid-liquid extraction, 10 kg of a solution containing 2 kg of solute C and 8 kg of solvent A is brought into contact with 10 kg of solvent B. Solvent A and B are completely immiscible in each other whereas solute C is soluble in both the solvents. The extraction process attains equilibrium. The equilibrium relationship between the two phases is Y* = 0.9X, where Y* is the kg of C/kg of B and X is kg of C/kg of A. Choose the correct answer. Read More »

CHEMICAL ENGINEERING, Mass Transfer

Acetone is to be removed from air in an isothermal dilute absorber using pure water as solvent. The incoming air contains 5 mole% of acetone (yin = 0.05). The design equation to be used for obtaining the number of trays (N) of the absorber is, N+2 = 6 log (yin/yout).For 98% recovery of acetone, the number of trays required is/are

CHEMICAL ENGINEERING, Mass Transfer /
Question: Acetone is to be removed from air in an isothermal dilute absorber using pure water as solvent. The incoming air contains 5 mole% of acetone (yin = 0.05). The design equation to be used for obtaining the number of trays (N) of the absorber is, N+2 = 6 log (yin/yout).For 98% recovery of acetone, the number of trays required is/are
[A].

1

[B].

8

[C].

9

[D].

10

Answer: Option C

Explanation:

No answer description available for this question.

Acetone is to be removed from air in an isothermal dilute absorber using pure water as solvent. The incoming air contains 5 mole% of acetone (yin = 0.05). The design equation to be used for obtaining the number of trays (N) of the absorber is, N+2 = 6 log (yin/yout).For 98% recovery of acetone, the number of trays required is/are Read More »

CHEMICAL ENGINEERING, Mass Transfer

An air-water vapour mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapour pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively.The humidity of air sample expressed as kg of water vapour/kg of dry air is

CHEMICAL ENGINEERING, Mass Transfer /
Question: An air-water vapour mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapour pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively.The humidity of air sample expressed as kg of water vapour/kg of dry air is
[A].

0.048

[B].

0.079

[C].

0.122

[D].

0.152

Answer: Option D

Explanation:

No answer description available for this question.

An air-water vapour mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapour pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively.The humidity of air sample expressed as kg of water vapour/kg of dry air is Read More »

CHEMICAL ENGINEERING, Mass Transfer

A distillation column separates 10000 kg/hr of a benzene-toluene mixture as shown in the figure below :In the figure xF, xD and xW represent the weight fraction of benzene in the feed, distillate and residue respectively. The reflux ratio is

CHEMICAL ENGINEERING, Mass Transfer /
Question: A distillation column separates 10000 kg/hr of a benzene-toluene mixture as shown in the figure below :In the figure xF, xD and xW represent the weight fraction of benzene in the feed, distillate and residue respectively. The reflux ratio is
[A].

0.5

[B].

0.6

[C].

1.0

[D].

2.0

Answer: Option B

Explanation:

No answer description available for this question.

A distillation column separates 10000 kg/hr of a benzene-toluene mixture as shown in the figure below :In the figure xF, xD and xW represent the weight fraction of benzene in the feed, distillate and residue respectively. The reflux ratio is Read More »

CHEMICAL ENGINEERING, Mass Transfer