1. Changes of State
Chapter 3, Section 2
Page 96

2. Section 2: Changes of State
What happens to a substance during changes between solid and liquid?
What happens to a substance during changes between liquid and gas?
What happens to a substance during changes between solid and gas?

3. Changes Between Solid and Liquid
The change in state from a solid to a liquid is called melting.
The temperature at which a solid melts is its melting point.

4. Changes Between Solid and Liquid
The change from a liquid to a solid is called freezing.
The temperature at which a liquid freezes is its freezing point.

5. Changes Between Liquid and Gas
The change from a liquid to a gas is called vaporization.

6. Water vapor on a lake’s surface.
Evaporation
Evaporation is when vaporization takes place only on the surface of a liquid.
Water vapor on a lake’s surface.

7. Boiling
Boiling is when vaporization takes place below its surface as well as at the surface of a liquid.
The temperature at which a liquid begins to boil is its boiling point.

8. Condensation Condensation is when a gas changes into a liquid.
animation
Condensation on a bus window

9. Temperature and Changes of State
A beaker of ice at –10ºC was slowly heated to 110ºC. The graph shows how the temperature of the water changed over time.
Animation

10. Temperature and Changes of State
Reading Graphs:
What two variables are plotted on the graph?
Temperature (ºC) on the y-axis, time (minutes) on the x-axis

11. Temperature and Changes of State
Reading Graphs:
What is happening to the temperature of the water during segment C of the graph?
The temperature is rising from 0ºC to 100ºC.

12. Temperature and Changes of State
Interpreting Data:
What does the temperature value for segment B represent? For segment D?
Segment B: melting point of ice; segment D: boiling point of water

13. Temperature and Changes of State
Drawing Conclusions:
What change of state is occurring during segment B of the graph? During segment D?
Change from solid to liquid; change from liquid to gas

14. Changes Between Solid and Gas
There are times when a solid will change directly into a gas. This process is called sublimation.
Snow
Dry Ice

15. End of Section: Changes of State