1. Chapter 3, Section 3
Changes in State

2. Change of State
Change of State: change of a substance from one physical form to another
Change of state happens by:
removing or adding energy!
Which changes the particle speed, the temperature, and finally the state changes!

3. ENDO vs. EXO Endothermic: Add Energy Exothermic: Remove Energy EX:
To add energy, increase the temperature, the particle movement increases
Exothermic: Remove Energy
To remove energy, decrease the temperature, the particle movement decreases
EX:
Boiling Water. ENDO or EXO
Freeze Water. ENDO or EXO

5. Solid to Liquid?
MELTING

6. Melting Endothermic Process Adds energy Temperature increases
Particles move faster
When a certain temperature is reached, the solid will melt (melting point)

7. Liquid to Solid?
FREEZING

8. Freezing Exothermic Process Freezing is the reverse of melting
Removes energy
Temperature decreases
Particles slow down
When the liquid reaches a certain temperature, the liquid will become a solid (freezing point)
Freezing is the reverse of melting

9. Liquid to Gas?
EVAPORATION
BOILING

10. Evaporation Occurs at the surface Endothermic Process Adds energy
Temperature increases
As the surface reaches a certain temperature, the surface particles change to gas
Happens before the liquid reaches its boiling point

11. Boiling Occurs throughout the liquid Endothermic Process Adds energy
Temperature increases
Particles move faster
Temperature at which a liquid boils is its boiling point

13. Gas to Liquid?
CONDENSATION

14. Condensation Exothermic Process
Remove energy
Temperature decreases
Particle movement decreases
Particles clump together
Temperature at which a gas becomes a liquid is the condensation point
Condensation and vaporization are the reverse of each other

15. Solid to Gas?
SUBLIMATION

16. Sublimation Endothermic Process Adds energy Temperature increases
Particle movement increases

17. Comparing Changes of State