phase equilibrium : single component
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Phase Equilibrium : Single Component. 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. - PowerPoint PPT PresentationTRANSCRIPT
Phase Equilibrium:Single Component
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
The same amount of solid iodine is added to two identical glass tubes, which are sealed and heated to 50°C. The color in both tubes is the same. Each has solid iodine in the bottom. When more iodine crystals are added to one tube, the vapor in that tube _______.
A. becomes darker
B. remains the same
C. becomes lighter
Iodine
50°C
Iodine
50°C
Vapor0.1 mol
Liquid0.9 mol
A piston-cylinder at 45°C and 0.5 bar contains 0.9 mol of hexane liquid and 0.1 mol of hexane vapor in equilibrium. The pressure is doubled at constant temperature by pushing down on the piston. What happens?
A. Most of the vapor condenses
B. All the vapor condenses, the liquidis below its saturation temperature
C. All vapor condenses, the liquid is below its saturation pressure.
D. The system contains only vapor
Vapor0.1 mol
Liquid0.9 mol
A piston-cylinder at 45°C and 0.5 bar contains 0.9 mol of hexane liquid and 0.1 mol of hexane vapor in equilibrium. Weights are removed from the piston to decrease the pressure to half its original value at constant temperature. What happens?
A. Most of the liquid evaporates
B. The liquid all evaporates, the vapor is above its saturation pressure
C. The liquid all evaporates, the vapor is above its saturation temperature
D. The system contains only liquid
Vapor0.1 mol
Liquid0.9 mol
A piston-cylinder at 45°C and 0.5 bar contains 0.9 mol of hexane liquid and 0.1 mol of hexane vapor in equilibrium. The temperature is lowered to 40°C at constant pressure.What happens?
A. Some of the vapor condenses
B. The vapor all condenses, the liquidis below its saturation temperature
C. The vapor all condenses, the liquidis below its saturation pressure
D. The system contains only liquid
1 kg
CH4
Vapor
10 bar300 K
Methane gas at 10 bar and 300 K is in a piston-cylinder. If more and more weight is added to the system, what eventually happens?
A. Gas becomes more dense
B. Some liquid forms
C. All the vapor becomes liquid
D. All the vapor becomes solid
Vapor0.2 mol
Liquid0.5 mol
A piston-cylinder at 45°C and 0.5 bar contains 0.5 mol of hexane liquid and 0.2 mol of hexane vapor in equilibrium. What happens when 0.1 mol hexane vapor is removed at constant pressure and temperature?
A. Some of the liquid evaporates
B. All of the liquid evaporates
C. No liquid evaporates
D. Some vapor condenses
E. All of the vapor condenses
1 kg0.1 mol vapor
Vapor0.1 mol
Liquid0.9 mol
A fixed-volume container at 45°C and 0.5 bar contains 0.9 mol of hexane liquid and 0.1 mol of hexane vapor in equilibrium. The temperature is lowered to 40°C. What happens? A. Some of the vapor condenses
B. All of the vapor condenses
C. Some of the liquid evaporates
D. All of the liquid evaporates
A fixed-volume container at 45°C contains 1 L of liquid benzene and 1 L of benzene vapor in equilibrium. If 0.4 L liquid benzene is removed and the container is at constant temperature and volume, the pressure ____________.
A. increases
B. decreases
C. remains the same
D. Not enough information. Liquid1 L
Vapor1 L
0.4 Lliquid
A fixed-volume container at 45°C contains 1 L of liquid benzene and 1 L of benzene vapor and air in equilibrium. If 0.4 L liquid benzene is removed and the container is at constant temperature and volume, the total pressure ____________.
A. increases
B. decreases
C. remains the same
D. Not enough information.
Liquid1 L
Vapor1 L
0.4 Lliquid
A fixed-volume container at 45°C contains 1 L of liquid benzene and 1 L of benzene vapor in equilibrium. If 0.4 L liquid benzene is removed and the container is at constant temperature and volume, then in the container, ___________________.
A. some liquid evaporates
B. some vapor condenses
C. the amount of vapor does not change
Liquid1 L
Vapor1 L
0.4 Lliquid
A fixed-volume container at 45°C contains 1 L of liquid benzene and 1 L of benzene vapor and air in equilibrium. If 0.4 L liquid benzene is removed and the container is at constant temperature and volume, then in the container, ___________________.
A. some liquid evaporates
B. some vapor condenses
C. the amount of vapor does not change
Liquid1 L
Vapor1 L
0.4 Lliquid
Vapor0.1 mol
Liquid5 mol
A fixed-volume container at 45°C contains 5 mol hexane liquid and 0.1 mol hexane vapor in equilibrium. An additional 0.2 mol of hexane vapor are added, while keeping the temperature constant. What happens?
A. Some of the added vapor condenses
B. All the added vapor condenses
C. Some of the liquid evaporates
D. All of the liquid evaporates
0.2 mol vapor
Vapor0.1 mol
Liquid5 mol
A fixed-volume container at 45°C contains 5 mol hexane liquid and 0.1 mol hexane vapor in equilibrium. An additional 0.2 mol of hexane vapor are added, while keeping the temperature constant. The pressure ___________.
A. increases
B. decreases
C. remains the same
0.2 mol vapor
Vapor0.1 mol
Liquid0.5 mol
A fixed-volume container at 45°C contains 0.5 mol of hexane liquid and 0.1 mol of hexane vapor in equilibrium. What happens when 0.2 mol hexane vapor is added at constant temperature?
A. Some of the added vapor condenses
B. The liquid all evaporates
C. Most of the liquid evaporates
D. All the added vapor condenses
E. All the added vapor and some original vapor condenses
0.2 mol vapor
Vapor0.2 mol
Liquid0.5 mol
A piston-cylinder at 45°C and 0.5 bar contains 0.5 mol of hexane liquid and 0.2 mol of hexane vapor in equilibrium. What happens when 0.1 mol hexane vapor is removed at constant temperature?
A. Some of the liquid evaporates
B. All of the liquid evaporates
C. No liquid evaporates
D. Some vapor condenses
E. All of the vapor condenses 45°C
0.1 mol vapor
CO2 solid and vapor are in equilibrium at -70°C and 0.2 MPa in a piston/cylinder. The pressure increasesto 0.3 MPa at -70°C. What happens?
A. Some vapor condenses
B. All the vapor condenses
C. Some solid sublimes
D. All the solid sublimesCO2
Vapor
CO2
Solid
A piston-cylinder at 45°C and 0.5 bar contains hexane in VLE. 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
A piston-cylinder at 45°C and below atmospheric pressure contains 0.9 mol of hexane liquid and 0.1 mol of 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 evaporates
C. All the liquid evaporates
D. All the vapor condenses
E. Some of the vapor condenses
0.1 molVapor
0.9 molLiquid
Pure CO2 is in solid‐vapor equilibrium in a piston-cylinder at 1 bar. On a molar basis, 50% of the CO2 is in the solid phase, but the solid occupies only 5% of the volume. If the volume of the container is decreased to half its value by pushing down on the piston at constant T, what will be the final pressure of the system?
A. 1 bar
B. 2 bar
C. A little less than 2 bar
D. A little more than 2 bar Solid50% CO2
V1 ½ V1
T1 T1
P
V
System
x
0.7 0.3
For this single component P-V diagram, what is thefraction of the material that is liquid?
A. 0.3
B. 0.7
C. 3/7 th
Which statement about the diagram is not true?
A. Components 1 and 2 have attractive interactions
B. A liquid at the azeotrope composition boils at constant temperature
C. Activity coefficients < 1
D. Since P1sat > P2
sat , the gas is enriched in component 1
E. Distillation cannot be used to obtain a pure material x1, y1
P
Azeotrope
0 0.5 1.0
P-x1
P-y1
Pure benzene is cooled from 10 torr and 26°C to10 torr and -30°C. Which line represents the pathway that will be followed?
Temperature (°C)
Ben
zene
par
tial
pre
ssur
e (to
rr)
LiquidSolid
Vapor
1
10
100
1000
-40 -20 0 20 40
Starting point
A
B
Benzene in air is cooled from 760 torr and 26°C to 760 torr and -30°C. The plot represents the benzene partial pressure. Which line represents the pathway that will be followed?
Temperature (°C)
Ben
zene
par
tial
pre
ssur
e (to
rr)
LiquidSolid
Vapor
1
10
100
1000
-40 -20 0 20 40
Starting point
A
B
Consider octane in VLE in a container of fixed volume. As the temperature increases, ___________.
A. all the liquid evaporates
B. all the gas condenses
C. the difference between liquid and vapor disappears,
D. either A or C can occur
E. A, B, or C can occurP
ln (V)
A stream containing wet steam (96% vapor, 4% entrained liquid) mixes with a N2 stream. Both streams are at 1 bar and 100°C. After mixing, the temperature ________________.
A. increases
B. decreases
C. remains the same
Steam
N2
1 L of liquid ethanol is added to a 5 L container and also to a 10 L container. Both containers are at the same temperature, and both have only ethanol in them. Which is true at equilibrium ?
A. PI < PII
B. PI = PII
C. PI > PII
I
II
1 L of ethanol(l) is added to a 5 L container and to a 10 L container. The volumes of the containers are fixed and at room temperature. If the containers only contain ethanol, the pressure in the 10 L container is _________ in the 5 L container.
A. greater than
B. lesser than
C. the same as
D. half the pressure
5 L
10 L
1 L of ethanol(l) is added to a 5 L container and to a 10 L container. The volumes of the containers are fixed and at room temperature. If the containers only contain ethanol, it is in ___________in both containers.
A. a liquid phase
B. a vapor phase
C. both a liquid and vapor phase
D. None of the above.
5 L
10 L
Liquid ethanol becomes a solid when the pressure increases isothermally. The Gibbs free energy of the ethanol ____________.
A. increases
B. decreases
C. remains the same
Ethanol starts as a vapor. Both its temperature and pressure are below the triple point. At constant temperature, you raise the pressure. What phases do you see as you increase pressure?
A. Gas Liquid Solid
B. Gas Liquid
C. Gas Solid
D. Gas Solid Liquid
A can of office duster (used for cleaning cameras and keyboards) contains a liquid-vapor mixture of 1,1,1,2-tetrafluoroethane (TFE). If the container is used continuously by depressing the nozzle, the flow rate of air ______________________________ .
A. decreases because the amount of TFE decreases
B. decreases because the temperature decreases
C. remains constant until all the liquid is used up
D. remains constant and then decreases
Why does water have a higher boiling point than cyclohexane?
A. Water takes up less space
B. Water experiences stronger intermolecular interactions
C. Water has a lower molecular weight
The square well potential for two molecules is shown. Compared to molecule 2, molecule 1 is ________ and has _________ intermolecular interactions.
A. larger; stronger
B. smaller; stronger
C. larger; weaker
D. smaller; weaker
r u(r)
1 2