1. Prentice-Hall Chapter 13.4 Dr. Yager
Changes of State
Prentice-Hall Chapter 13.4
Dr. Yager

2. Objectives Identify the conditions necessary for sublimation.
Describe how equilibrium conditions are represented in a phase diagram.

3. Four States of Matter
Solid
Liquid
Gas or Vapor
Plasma

4. Changes in State Solid to Liquid – Melting
Liquid to Gas – Boiling, evaporation
Vapor to Liquid – Condensation
Liquid to Solid – Freezing
Solid to Vapor – Sublimation
Vapor to Solid – Deposition
Vapor to Plasma – Hot, Hot, Hot!!!

5. Sublimation
sublimation: the change in state from solid to vapor without passing through the liquid state
Sublimation occurs in solids with vapor pressures that exceed atmospheric pressures at or near room temperature.

6. When solid iodine is heated, the crystals sublime, going directly from the solid to the gaseous state.
When the vapor cools, it goes directly from the gaseous to the solid state.

7. Uses of Sublimation Dry Ice - keep ice cream frozen
Freeze Dried Coffee - vacuum pump over ice
Solid Air Fresheners
Separation of materials by organic chemistry

8. Phase Diagrams Key Idea
phase diagram: a graph which shows the relationship among solid, liquid and gas
The two axes for a fixed volume are pressure (y-axis) and temperature (x-axis).
Key Idea
When two phases exist in equilibrium they are indicated on a phase diagram by a line separating the phases.

10. The triple point describes the only set of conditions at which all three phases can exist in equilibrium with one another.
For water this occurs at oC and 0.61 kPa.

11. Phase Diagram of CO2

13. Why Does Ice Float?

14. Identify the change of state that occurs when solid CO2 changes to CO2 gas as it is heated.
condensation
freezing
vaporization
sublimation

15. Identify the change of state that occurs when solid CO2 changes to CO2 gas as it is heated.
condensation
freezing
vaporization
sublimation

16. 2. Sublimation occurs in solids if the vapor pressure at or near room temperature
exceeds atmospheric pressure.
equals atmospheric pressure.
is less than atmospheric pressure.
is less than half the atmospheric pressure.

17. 2. Sublimation occurs in solids if the vapor pressure at or near room temperature
exceeds atmospheric pressure.
equals atmospheric pressure.
is less than atmospheric pressure.
is less than half the atmospheric pressure.

18. 3. What is the significance of a line in a phase diagram?
Only one phase is present.
Two phases are in equilibrium.
Three phases are in equilibrium.
The distinction between two phases disappears.

19. 3. What is the significance of a line in a phase diagram?
Only one phase is present.
Two phases are in equilibrium.
Three phases are in equilibrium.
The distinction between two phases disappears.

20. 4. What is the significance of the triple point in a phase diagram?
Temperature and pressure are equal.
Two phases are in equilibrium.
Three phases are in equilibrium.
The distinction among three phases disappears.

21. 4. What is the significance of the triple point in a phase diagram?
Temperature and pressure are equal.
Two phases are in equilibrium.
Three phases are in equilibrium.
The distinction among three phases disappears.