1. -Boiling/Condensation and Melting/Freezing Points
CST Review Session 2
-Solids, Liquids, Gases
-Phase Changes
-Boiling/Condensation and
Melting/Freezing Points

2. There are THREE states of matter:
Packing of Particles
Movement of Particles
Energy Possessed by Particles
Solids
Particles packed close to one another.
Particles vibrate in place; locked in position.
Little KE possessed by particles.
Liquid
Particles are more loosely arranged; can roll over one another.
More KE possessed; Liquid particles can flow.
Gas
Most disorderly state; particles far apart from each other; have little attraction for one another.
Gas particles dart about, colliding with each other and with walls of container.
Gas particles possess the most KE. b
KE stands for Kinetic Energy

3. Recall: A fluid is a LIQUID or a GAS!
Solid Liquid Gas
Application or Removal of HEAT ENERGY converts matter from one state to another.
The addition of heat causes a change of state.

4. Checkpoint SOLID GAS LIQUID
Which state is characterized by particles that can only vibrate in place?
Which state is characterized by particles able to move freely and possess the most amount of KE?
Which state is characterized by particles that can slip and slide over one another but are still close to each other?
SOLID
GAS
LIQUID

5. Checkpoint LIQUID SOLID GAS 5. Is this a solid, liquid or gas?

6. Addition of Heatcauses particles to move faster.
EVAPORATION: When heat is applied to liquid water, some molecules “escape” to become a gas.
MELTING: heat is added to make ice melt into a liquid.

7. Adding heat changes a solid to a liquid, and a liquid to a gas.
Melting
Evaporation
SOLID
LIQUID
GAS
Melting Point
Boiling Point
Adding heat changes a solid to a liquid, and a liquid to a gas.

8. Removing HEAT! FREEZING Freezing Condensation
By doing this, a gas changes to a liquid!
Removing HEAT!
Or change a liquid to a solid!
FREEZING
Freezing
Condensation
SOLID
LIQUID
GAS
Freezing Point
Condensation Point

9. When it’s very cold, snow forms (freezing).
Water vapor condenses [becomes dew] on leaves when it gets cold (condensation).
When it’s very cold, snow forms (freezing).

10. All changes in state are just PHYSICAL CHANGES- the composition and identity of the substances are NOT changed.

11. Q. Substance X melts at 40oC and boils at 125oC
Q. Substance X melts at 40oC and boils at 125oC. At what state will it be at the following temperature?
a. 100oC? B. 17oC?
SOLID
LIQUID
GAS
Melting Point Boiling Point 40
125