1. Phase Change

2. Phases of Matter The properties of solids, liquids, and gases differ.
How does matter change state?
Solid
Liquid
Gas

3. Energy of Phase
Internal energy can be stored as bonds between atoms and molecules.
Solids have the strongest bonds
Energy required to break them to a liquid

4. Filling the Volume Unlike a liquid, gas fills the whole volume.
Atoms are free to move.
Volume depends on pressure and temperature.
liquid
gas

5. Phase Diagrams
For each temperature and pressure a material is in a specific state.
The triple point is uniquely defined for each material.
P3 for water is used to define the Kelvin
The critical point is where there is no difference between liquid and gas.
Phase diagram for water

6. Sublimation
At low pressures a solid can go directly to a gas and vice versa.
This process is called sublimation.
Dry ice to gaseous carbon dioxide
Water vapor to frost
There is a latent heat of sublimation
Phase diagram for carbon dioxide

7. Partial Pressure

8. Dalton’s Law

9. Relative Humidity