Reading Phase Diagrams
Cooling Curves
Heating Curves
Phase Changes
Pressure
100
What are the coordinates of the triple point?
(.661 kPa, .01 C)
100
What phase change occurs at 100 C? What is this point called?
Condensation
It is called the Boiling Point
100
Which state of matter is excluded when the only phase change in a heating curve is sublimation?
Liquid
100
Which 2 phase changes can happen along the boiling point?
Vaporization and Condensation depending on whether its a heating or cooling curve
100
True or False: Pressure can influence the phase of a pure substance
True, Pressure can influence the phase of a pure substance
200
Normal Melting and Boiling Points are at 101.3 kPa based on this diagram. What temperature is the normal melting point at?
0 C
200
What phase change is occurring at 20 C? What is this point called?
Freezing
Melting or Freezing Point
200
If Compound Z has a melting point of −50°C and a boiling point of 58°C, in what phase would Compound Z be at 58°C? Explain why
The phase would be a mix of liquid and gas because a phase change is occurring
200
Which 2 phase changes can occur on the melting point?
Melting and Freezing, depending on whether its a heating or cooling curve
200
Recently, you learned heating curves show energy (temperature) change under constant pressure. But constant pressure is not the case for ALL scientific scenarios. Such graphs that show changing temperature and changing pressure are called...
Phase Diagrams
300
At Standard Pressure (101.3 kPa), I increased the temperature of the compound from -79 C to 374 C. What phase changes occurred?
Melting from Solid to Liquid and then Vaporizing from Liquid to Gas.
300
Describe the lines that represent the melting and boiling point. Explain why these lines look that way.
Horizontal (Flat) Lines
The lines are horizontal because the energy is being used to change phase instead of increase or decrease temperature
300
Name numbers on the line segments representing phase changes? What are these phase changes?
2 and 4
2 is melting
4 is vaporization
300
Which phase changes can occur on the sublimation point?
Sublimation or Deposition, depending on whether its a heating or cooling curve
300
Would you expect water to boil at higher or lower temperatures at the top of Mount Everest (where there is lower pressure)?
lower
400
Below which value of pressure can Sublimation occur if the temperature is increased from -79 C to 100 C?
Below 0.611 kPa
400
At what temperature does deposition occur on this cooling curve?
No temperature, deposition is not occurring!
400
What numbers are states of matter? What are the states of matter listed?
1= Solid
3= Liquid
5= Gas
400
Name this phase change:
Particles go from very fast, and far apart to immediately slowed down and compact. There is no intermediate state because the pressure is lower than the triple point
Deposition
400
The ball represents a gas particle between two container walls. A student models gas pressure by swinging the ball so it hits the two walls alternately, creating a pressure. How should the student change the setup to show an increase in pressure caused by an increase in temperature?
Swing the ball faster, so it hits the walls more frequently, due to an increase in kinetic energy (particle motion).
500
Which phase change (between one state of matter and another state of matter) is occurring at letters A, C, and D?
(2 possible names for each letter: Double points if all 6 phase changes are named!)
A= Sublimation/Deposition
C=Melting/Freezing
D= Evaporation/Condensation
500
At what temperature does condensation occur?
100 C
500
At standard pressure, Compound A is a liquid at 200 degrees Celcius. What inference can you make about its boiling point and its pressure?
Boiling Point is above 200 C at 1 atm (standard air pressure)
500
Substance A has a melting point of 20 C and a boiling point at 200 C. What state of matter will substance A be at 40 C
Liquid
500
Why does the boiling point of water decrease at higher elevations?
At increasing altitude, atmospheric pressure declines. At a higher elevation, the lower atmospheric pressure means heated water reaches its boiling point more quickly—i.e., at a lower temperature.