1. Phases Of Matter CH23 Physics (B) Fall, 2010-2011 1

2. Phase (State) Changes First, what are the phases of matter? –Solid –Liquid –Gas –Plasma Phase depends on T and P, & amount of heat added or removed from substance 2

3. Phases of Matter Solids-molecules are slow moving, close together (except ice!), have a definite shape, have a definite volume Liquids-molecules are moving faster than solids, spreading apart, have a definite volume, but not a definite shape….liquids take the shape of the container Gases-molecules in constant motion, random & free, molecules are very far apart, no definite shape, no definite volume Plasma-similar to a gas, but contains charged particles with ooh-koo energy, exists at very high temps (K is used) 3

4. Phases of Matter If Plasma exists at high temps, then how does a Plasma TV work? http://videos.howstuffworks.com/science- channel/37745-deconstructed-plasma-tvs- video.htmhttp://videos.howstuffworks.com/science- channel/37745-deconstructed-plasma-tvs- video.htm How cool is that!?! 4

5. Phase Changes-How Does a Substance Change From One to Another? Two things required to change phases: 1.Energy Absorbed or Energy Released From Substance, i.e. Q or Q 2.Constant Temperature: ΔT = 0, Tfinal=Tinitial T=ONE TEMP. THE WHOLE TIME Phase changes can go Solid→ Liquid→ Gas OR Gas→ Liquid → Solid AND Solid → Gas (Sublimation) 5

6. Phase Diagram- Solid-to-Gas 6 Temp. (°C) -50 80 100 540 Heat Energy ADDED (cal) Melting Evaporating/ Vaporizing

7. Phase Diagram- Gas-to-Solid 7 Temp. (°C) -50 80 100 540 Heat Energy REMOVED (cal) Freezing Condensing

8. Phase Changes of Water There are five processes that deal with phase changes: –Evaporation –Condensation –Boiling –Freezing –Sublimation Let’s take a look…. 8

9. Phase Changes of Water Evaporation: Change of phase from liquid to gas that takes place at the surface of a liquid Condensation: Change of phase from gas to a liquid that takes place at the surface These two are direct opposite processes 9

10. Phase Changes of Water Boiling: Change of Phase from Liquid to gas BENEATH a liquid’s surface Freezing: Change of Phase from Liquid to solid at the surface of a liquid These two are direct opposite processes 10

11. Phase Change of Water But there is one funky process: Sublimation: The phase change from solid directly to gas from the surface of the solid Examples: Dry Ice (CO 2 solid form), Fog from snow 11

12. Let’s Go Witness This Stuff?! You Gotta See It To Believe It! 12