Phase Equilibrium:Single Condensable

ComponentPart 1

Contributions by:John L. Falconer & Will Medlin

Department of Chemical and Biological EngineeringUniversity of Colorado

Boulder, CO 80309-0424

Supported by the National Science Foundation

A container has liquid water (50% of the volume) andwater vapor (50% of the volume) in equilibrium.It is sealed so the volume is fixed. When the temperature is raised, the ___________.

A. liquid evaporates and the pressure increases

B. vapor condenses and the pressure increases

C. liquid and vapor both remain and pressure increases

Vapor

Water

Liquid water is in VLE at 1.2 bar with water vapor and air in a piston-cylinder. Half the air is removedthrough a selective membrane; no water leaves. Pressure and temperature are constant. What happens?

A. All of the water vaporizes

B. All of the water condenses

C. Some of the water vaporizes

D. Some of the water condenses

Vapor/air1.2 bar Air

Water

1 kg

Liquid water is in VLE at 1.2 bar with water vapor and air in a piston-cylinder. All the air is removedthrough a selective membrane and half the watervapor is also removed. Pressure and temperature are constant. What happens?

A. All of the water vaporizes

B. All of the water condenses

C. Some of the water vaporizes

D. Some of the water condenses

Vapor1.2 bar Air

Water

1 kg

Water Vapor

Liquid water is in VLE at 1.2 bar with water vapor and air in a piston-cylinder. Half the air and halfthe water vapor are removed. Pressure and temperature are constant. What happens?

A. All of the water vaporizes

B. All of the water condenses

C. Some of the water vaporizes

D. Some of the water condenses

E. No water vaporizes

Vapor1.2 bar Air

Water

1 kg

Water Vapor

Liquid water is in VLE at 1.2 bar with water vapor and air in a fixed-volume container. Half the air is removed through a selective membrane; no water leaves. Temperature is constant. What happens?

A. All of the water vaporizes

B. All of the water condenses

C. Some of the water vaporizes

D. Some of the water condenses

E. No water changes phase

Vapor1.2 bar

Air

Water

Liquid water is in equilibrium at 50°C with air in apiston-cylinder at 1 bar. The pressure is isothermally raised to 2 bar by pushing down onthe piston. The amount of water in the vapor phase __________.

A. increases

B. decreases

C. remains the same

D. Not enough informationVapor

Water

Liquid water is in equilibrium at 50°C with air in apiston-cylinder at 1 bar. The pressure is isothermally raised to 2 bar by pushing down onthe piston. The water partial pressure ________.

A. increases

B. decreases

C. remains the same

D. Not enough information Vapor

Water

A piston-cylinder at 45°C and 0.5 bar contains hexane in vapor-liquid equilibrium. You push down on the piston until the vapor volume is half its original volume. The system is at constant temperature. What is the pressure at the new equilibrium?

A. 0.25 bar

B. 0.5 bar

C. 1.0 bar

D. Cannot be determined

HexaneVapor

HexaneLiquid

Liquid water is in equilibrium at 50°C with air in apiston-cylinder at 1 bar. The temperature is lowered to 40°C. The partial pressure of the air ___________.

A. increases

B. decreases

C. remains the same

D. Not enough information

Vapor

Water

1 kg

Liquid water is in equilibrium at 50°C with air in apiston-cylinder at 1 bar. The temperature is lowered to 40°C. What happens to the water vapor?

A. Some of it condenses

B. All of it condenses

C. None of it condenses

D. More water evaporatesVapor

Water

1 kg

A piston and cylinder at 45oC and below atmospheric pressure contains 0.9 mol of n-hexane liquid and 0.1 mol of n-hexane vapor in equilibrium. Weights areremoved from the piston to decrease the pressure to 99% of its original value at constant temperature. What happens?

A. Some of the liquid evaporates B. Most of the liquid evaporatesC. All the liquid evaporatesD. All the vapor condensesE. Some of the vapor condenses

Vapor

Liquid

1 kg

Liquid water is in equilibrium at 50°C with air in afixed-volume container at 1 bar. The temperature is lowered to 40°C. The partial pressure of the air ___________.

A. increases

B. decreases

C. remains the same

D. Not enough information

Vapor1 bar

Water

Liquid water is equilibrium with air in a fixed volume container at 1.2 bar. Half the air and half the water vapor are removed. Temperature is constant. What happens?

A. All of the water vaporizes

B. All of the water condenses

C. Some of the water vaporizes

D. Some of the water condenses

E. No water changes phase

Vapor1.2 bar

Water

Liquid water is equilibrium with air in a fixed volume container at 1.2 bar. Half the air and half the water vapor are removed. Temperature is constant. The partial pressures of air and water __________.

A. decrease

B. increase

C. remain the same

D. Need more information.

Vapor1.2 bar

Water

Water is in VLE at 1.2 bar in a fixed-volume container. You inject 5 cm3 of air into the system, but keep the temperature constant. What happens?

A. All of the water vaporizes

B. All of the water condenses

C. Some of the water vaporizes

D. Some of the water condenses

E. No water changes phase

Vapor1.2 bar

Water

Air

Liquid water is in equilibrium at 50°C with air in apiston-cylinder at 1 bar. The temperature is raised to 60°C. What happens?

A. Some liquid evaporates

B. All liquid evaporates

C. No liquid evaporates

D. Some vapor condensesVapor

Water

1 kg

Liquid water is in equilibrium at 50°C with air in apiston-cylinder at 1 bar. The temperature is raised to 60°C. The partial pressure of the air ______________.

A. increases

B. decreases

C. remains the same

D. Not enough information.

Vapor

Water

1 kg

Liquid water is in equilibrium at 30°C with air in a piston-cylinder at 1 bar. The pressure is isothermally lowered to 0.85 bar by removing weights from the piston. The partial pressure of air ________.

A. increases

B. decreases

C. remains the same

D. Not enough information.

Vapor

Water

1 kg

Liquid water is in equilibrium at 30°C with air in a piston-cylinder at 1 bar. The pressure is isothermally lowered to 0.85 bar by removing weights from the piston. The partial pressure of water ________.

A. increases

B. decreases

C. remains the same

D. Not enough information.

Vapor

Water

1 kg

Liquid water is in equilibrium at 30°C with air in a piston-cylinder at 1 bar. The pressure is isothermally lowered to 0.85 bar by removing weights from the piston. What happens?

A. Some of the water vaporizes.

B. All of the water vaporizes.

C. No water vaporizes.

D. Not enough information.

Vapor

Water

1 kg

Vapor

Water

A piston-cylinder contains liquid water in equilibrium with air at 1 bar and 40°C. You inject water vapor into the system and let it equilibrate to 40°C. What happens to the injected water?

A.All of it condenses

B.All of it stays in the vapor phase

C.Some of it condenses

1 kg

Watervapor

Vapor

Water

A piston-cylinder contains liquid water in equilibrium with air at 1 bar and 40°C. You inject water liquid water into the system and let it equilibrate to 40°C. What happens to the injected water?

A.All of it vaporizes

B.All of it stays in the liquid phase

C.Some of it vaporizes

1 kg

Water

Vapor

Water

Water is in VLE at 1.2 bar in a piston-cylinder.You inject 5 cm3 of air into the system, but keeppressure and temperature constant. What happens?

A. All of the water vaporizes

B. All of the water condenses

C. Some of the water vaporizes

D. Some of the water condenses

1 kg

Air

Vapor

Water3.0 mol

Water is in VLE at 1.2 bar in a piston-cylinder. The system contains 3 mol of liquid water. You inject 5 cm3 of air into the system at the same temperature. The system is adiabatic. What happens?

A. All of the water vaporizes

B. All of the water condenses

C. Some of the water vaporizes

D. Some of the water condenses

Air

Vapor

Water3.0 mol

Water is in VLE at 1.2 bar in a piston-cylinder. The system contains 3 mol of liquid water. You inject 5 cm3 of air into the system at the same temperature. The system is adiabatic. The system temperature ____________.

A. increases

B. decreases

C. remains the same Air

An insulated container of water is in VLE at 250°C. When the valve is opened at the top of the container, the pressure __________ and the ___________?

A. stays the same; liquid level drops at constant temperature

B. decreases; temperature drops

C. decreases; temperature stays the same

D. stays the same; temperature drops.

Vapor

Water

An isothermal container of water is in VLE at 250°C. When the valve at the top of the container is opened to the atmosphere, the pressure __________ and the ___________?

A. stays the same; liquid level drops at constant temperature

B. decreases; temperature drops

C. decreases; temperature stays the same

D. stays the same; temperature drops.

Vapor

Water

Vapor

Water3.0 mol

Liquid water is in VLE with air at 1.2 bar in a piston-cylinder. The vapor volume is 3 cm3. You inject 1 cm3 of air, but keep pressure and temperature constant. The mole fraction of air in the gas ________.

A. increases

B. decreases

C. remains the same Air

1 kg

A fixed volume tank contains water in VLE. One mole of air is added to the system. All gases are ideal. The partial pressure of air ___________.

A. increases

B. decreases

C. stays the same

Air +

H2OVapor

LiquidH2O

1 mol Air

A fixed-volume tank contains liquid water and water vapor in VLE. One mole of air is added to the system. All gases are ideal. The partial pressure of water ____________.

A. increases

B. decreases

C. stays the same

Air +

H2OVapor

LiquidH2O

1 mol Air

A B

C D

This piston-cylinder contains air and water vapor (10% relative humidity). Which is the correct plot of partial pressure of water versus total pressure, as the total pressure on the gas increases?

Ptotal

PH

2O

Ptotal

PH

2O

Ptotal

PH

2O

Ptotal

PH

2O

Air &WaterVapor

(10% RH)

A

C

B

D

This piston-cylinder contains air and water vapor (50% relative humidity). Which is the correct plot of partial pressure of water versus temperature, as the temperature decreases?

PH

2O

T

PH

2O

T

TT

PH

2OP

H2O

Air &WaterVapor

(50% RH)

1 kg

A 500 cm3 fixed-volume container has air at 100°C and 1 bar. You inject 2 cm3 of liquid water that is at 25°C and let the system reach equilibrium at 100°C. What is the approximate final pressure?

A. 1 bar

B. 1.004 bar

C. 1.05 bar

D. 2 bar

E. None of the above

Air100°C1 bar

Water25°C