1. Phases Changes

2. Phase Changes By adding or taking away energy, phase changes occur.
Solid objects have the least amount of energy.
Gases have the a large amount of energy.
Plasma has the largest amount of energy.

4. Solid to a Liquid Melting is the change from a solid to a liquid.
Melting occurs when a solid absorbs heat energy.
The temperature at which this happens is called the Melting Point. Water = 0oC

5. Liquid to a Solid Freezing is the change from a liquid to a solid.
Occurs when a liquid loses energy.
Freezing point of a substance is equal to its melting point.

6. Cool Stuff with Freezing
Liquid Nitrogen – Boils at room temperature

7. Liquid to Gas Phase Change
Vaporization
The process of going from a liquid to a gas is called vaporization.
If the process occurs on the surface of the liquid it is evaporation.
Evaporation

8. Liquid to Gas Cont’d
Boiling is the process of gas traveling to the surface of a liquid and then to the air.
The temperature at which this happens is called the boiling point. Water is 100oC.

9. Gas to Liquid
The change from a gas to a liquid is called condensation.
Ex. Cold drinks become wet on the outside of the glass.

10. Solid to Gas Phase Change
The change from a solid to a gas is called sublimation.
The substance does not experience the liquid phase.
Dry Ice keeps items cold and dry.