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Fugacity. Contributions by: John L. Falconer & Will Medlin Department of Chemical and Biological Engineering University of Colorado Boulder, CO 80309-0424 Supported by the National Science Foundation. Which of the following will increase the fugacity of a component, A?.

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Fugacity

Fugacity

Contributions by:

John L. Falconer & Will MedlinDepartment of Chemical and Biological EngineeringUniversity of ColoradoBoulder, CO 80309-0424

Supported by the National Science Foundation


Fugacity

Which of the following will increase the fugacity of a component, A?

Convert from solid to liquid

Convert from liquid to solid

Decrease pressure

Dilute with component B

None of the above


Fugacity

What is the driving force for component A to move from liquid to vapor to reach equilibrium?

A. PressureB. EntropyC. EnthalpyD. ConcentrationE. Gibbs free energy

Vapor

yA

Liquid

xA


Fugacity

One component exists in two phases at the same temperature, but the phases are not in equilibrium. Which phase has the higher fugacity?

α

β

Same fugacity in each phase.

Not enough information.

0.1 mol/L

α phase

0.5 mol/L

ᵦphase


Fugacity

One component exists in two phases at the same temperature, but the phases are not in equilibrium. What is the direction of mass transfer?

From α to β.

From β to α.

No mass transfer occurs.

Cannot predict direction.

0.005 mol/L

α phase

0.10 mol/L

ᵦphase


Fugacity

A

B

H2O +EtOH

H2O

Two identical flasks at 45°C are connected by a tube. Flask A contains water and flask B contains 50% more water plus it contains ethanol. As the system approaches equilibrium, _______________________.

water moves from A to B

ethanol moves from B to A

water moves to B and ethanol moves to A

both water and ethanol move to A

there is no change in solution levels


Fugacity

A

B

H2O

35°C

H2O

40°C

Two identical flasks are connected by a tube. Flask A contains water at 40°C. Flask B contains 50% more water at 35°C. As the system approaches equilibrium, _______________.

water moves from A to B

water moves from B to A

no change occurs


Fugacity

A

B

H2O

40°C

H2O

40°C

Two identical flasks are connected by a tube. Flask A contains water at 40°C. Flask B contains 50% more water at 40°C. As the system approaches equilibrium, _______________.

water moves from A to B

water moves from B to A

no change occurs


Fugacity

A

B

H2O

40°C

+NaCl

H2O

40°C

Two identical flasks contain water at 40°C and are connected by a tube. NaCl is added to flask B. As the system approaches equilibrium, ______________.

water moves from A to B

water moves from B to A

no change in levels occur


Fugacity

A

B

98% H2O

+2% EtOH

55°C

H2O

45°C

Two identical flasks are connected by a tube. Flask A contains water at 45°C. Flask B contains twice the volume of A but is a 98% H2O/ 2% ethanol mixture at 55°C. As the system approaches equilibrium, _______.

water moves from A to B

ethanol moves from B to A

water moves to B and ethanol to A

both water and ethanol move to A

no change in levels occur


Fugacity

A

B

Pure H2O

22oC

NaCl

Solution

25oC

Flask A contains a NaCl solution at 25°C in equilibrium with the pure water at 22°C in flask B.

PH2Osat(25°C) = 3.2 kPa PH2Osat(22°C) = 2.6 kPa

Estimate the fugacity of water in the NaCl solution.

3.2 kPa

2.6 kPa

< 2.6 kPa

> 3.2 kPa

> 2.6 kPa


Fugacity

A

B

80% H2O

45°C

+20% NaCl

H2O

45°C

Two flasks at 45°C are connected by a tube. Flask A contains H2O, and flask B contains the same amount of an 80/20 mixture of H2O and NaCl. After 5 hours, ________.

Beaker A has more water

Beaker B has more water

The amounts of water do not change since they are at the same temperature

All the salt moves to beaker A


Fugacity

A

B

H2O

45°CNaCl

+

5 g KCl

H2O

45°C

NaCl

Two flasks at 45°C are connected by a tube. Flask A contains water and NaCl. Flask B contains 50% more water and also contains NaCl. The system is at equilibrium. When 5 g of KCl is added to Flask B, _________________.

water moves from B to A

water moves from A to B

KCl moves from B to A

nothing changes


Fugacity

Adsorption concentrates a molecule on a surfacefrom another phase. Consider hexane liquid and

vapor. The hexane concentration in the zeolite pores is ____________.

higher in A

higher in B

the same in both

Insufficient information

B

A

Vapor

Vapor

Porous zeolite crystals

Liquid

Liquid


Fugacity

Two systems have acetone/hexane in vapor-liquid equilibrium at the same temperature. Acetone is enriched in the vapor phase. Both molecules adsorb on the zeolite surface, where they have a higher concentration than in the gas phase. Which arrangement will have a

higher concentration of

acetone adsorbed on the

zeolite crystals?

Higher in A

Higher in B

The same in both

Insufficient information

A

B

Vapor

50/50

Vapor

Porous zeolitecrystals

50/50

Liquid

Liquid


Fugacity

Two systems have acetone/hexane in vapor-liquid equilibrium at the same temperature. Acetone is enriched in the vapor phase. Both molecules adsorb on the zeolite surface, where they have a higher concentration than in the gas phase. Which arrangement will have a

higher concentration of

acetone adsorbed on the

zeolite crystals?

Higher in A

Higher in B

The same in both

Insufficient information

A

B

50/50Vapor

Vapor

Porous zeolitecrystals

Liquid

50/50Liquid


Fugacity

2

2

P

P

1

1

V

V

As the pressure increases from point 1 to 2,

which figure shows an area proportional to the change

in Gibbs free energy?

A

B


Fugacity

f

f

f

f

P

P

P

P

Which plot represents f vs. P for an ideal gas?

A

B

C

D


Fugacity

For the H-xA diagram at 80°C, what is the maximumvalue of the partial molar enthalpy of component Aat 80°C?

50 cal/mol

22 cal/mol

85 cal/mol

100 cal/mol

0 cal/mol

100

100

H (cal/mol)

50

50

0

0

0

0.5

1.0

xA


Fugacity

A

B

D

C

E

An isotherm for a cubic equation of state is shown below. Which line corresponds to a vapor-liquid equilibrium?

Pressure

n/V


Fugacity

When both vapor and liquid are present, the fugacity at x1 = 0.1 will be ________ at x1 = 0.3.

greater than

less than

equal to the value

P

0.1

0.3

0.5


Fugacity

When both vapor and liquid are present, the fugacity at x1 = 0.1 will be ________ at x1 = 0.3, because ________.

greater than; pressure is higher

less than; mole fraction is lower

less than; partial pressure is higher

equal to the value; its at equilibrium.

P

0.1

0.3

0.5


Fugacity

20 bar

A metal box of fixed volume contains CO2 at a pressure of 2 bar. Through a valve you add CH4 at a constant rate and at constant temperature. Which plot represents how CH4 fugacity changes with time up to a total pressure of 20 bar? Assume ideal gases.

None of the above.

2 bar

Time

Time

Time

Time

A

B

C

D

fugacity

0 bar


Fugacity

A metal box of fixed volume contains CO2 at 2 bar pressure. Methane was added at a constant rate and at constant temperature. Which is the most likely plot of CH4 fugacity vs. time up to a total pressure of 20 bar? Assume ideal gases.

A

B

C

D

20 bar

10 bar

2 bar

Time

Time

Time

Time


Fugacity

Liquid water is in equilibrium with water vapor and air.

Ptot= 1.2 bar

PH2O= 0.1 bar

The fugacity of water is about __________.

0.1 bar.

1.2 bar.

1.00 (dimensionless).

Cannot be determined.


Fugacity

The boiling point of water at 1 bar is 100°C.

At 150°C the boiling point is 4.7 bar.The fugacityof water at 150°C and 100 bar is closer to ______ bar.

1

5

50

100


Fugacity

When comparing steam at 100°C to water at 100°C, steam has a higher enthalpy, _______, and ________.

higher entropy, higher Gibbs free energy

higher entropy, the same Gibbs free energy

the same entropy, the same Gibbs free energy

lower entropy, lower Gibbs free energy


Fugacity

1 kg of ice and 1 kg of liquid water are at equilibrium at 0°C. When liquid ethanol is added and the temperature is kept at 0oC, _______________.

some ethanol freezes

some water freezes

some ice melts

all the ice melts

all the ethanol freezes


Fugacity

Air is bubbled through a tank of water at 25oC and atmospheric pressure. The solubility of O2 in water is about 0.005 mol% at 25oC. Estimate the fugacity of oxygen in the water.

1 bar

0.2 bar

0.5 bar

2 bar

0.0005 bar


Fugacity

A pure-component fluid is at 10 bar and 350 K. The Peng-Robinson equation of state has three real roots:

1) V = 0.080 L/mol ; fugacity = 11 bar

2) V = 8 L/mol ; fugacity = 9 bar

The fluid is a ____________.

liquid

gas

2-phase mixture

supercritical fluid


Fugacity

A pure-component fluid is at 10 bar and 350 K. The Peng-Robinson equation of state has three real roots:

1) density = 25 mol/L; fugacity = 11 bar

2) density = 0.2 mol/L; fugacity = 9 bar

The fluid is a ____________.

liquid

gas

2-phase mixture

supercritical fluid


Fugacity

Boiling point of water: Psat= 1.0 bar; Tsat= 100°C

Psat= 4.7 bar; Tsat= 150°C

The fugacity of water at 150°C and 100 bar is closer to __________.

1 bar

5 bar

50 bar

100 bar


Fugacity

Which of the following will increase the fugacity of a component, A?

Convert from solid to liquid

Convert from liquid to solid

Decrease pressure

Dilute with component B

None of the above


Fugacity

If you were to boil water on a stove in a small room for an hour, the fugacity of the ______________.

liquid increases

water vapor increases

liquid decreases

water vapor decreases

water stays the same in the vapor

H2O


Fugacity

Soda (liquid water with a low concentration of dissolved CO2) at 0°C is compressed to 5 bar soonly a liquid phase remains. In the liquid phase, the fugacity of ___________.

water is higher

CO2 is higher

water and CO2 are the same


Fugacity

A can of soda at 0°C contains liquid water with a low concentration of dissolved CO2. If the CO2 pressure in the can is slightly above 1 bar, which has a higher fugacity in the liquid phase?

Water

CO2

Fugacities of water and CO2 are equal


Fugacity

When salt is added to pure water, what happens to the fugacity of the water?

increases

decreases

stays the same


Fugacity

Pure NaCl was added to pure water until thewater was saturated and the excess salt settled to the bottom of the container. What happened to the fugacity of the salt?

Increased

Decreased

Did not change


Fugacity

Compared to the fugacity of pure water, the fugacity of water in a saline solution will be _________.

higher

lower

the same


Fugacity

Pure NaCl was added to pure water until thewater was saturated and the excess salt settled to the bottom of the container. The fugacity of the dissolvedsalt is __________ the fugacity of the pure NaCl.

higher

lower

the same as


Fugacity

A liquid containing 60 mol% salt and 40 mol% water is in equilibrium with water vapor at 0.5 bar. Which species has the higher fugacity in the liquid?

Salt

Water

Their fugacities are equal

Need more information


Fugacity

A sealed container of water is at high enough pressureso that no vapor is present. The water contains 0.2 mol% salt and 0.2 mol% CO2.

Which component has the highest fugacity?

Water

CO2

Salt

Same for all


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