1. Changes in States of Matter

2. Changes in States of Matter
Change in State
Process of Change
Melting
Freezing
Boiling (Vaporization)
Condensation
Sublimation
Deposition
solid to liquid
liquid to solid
liquid to gas
gas to liquid
Solid to gas
Gas to solid

3. Liquid to Gas Phase Change
Vaporization - the change from a liquid to a gas below its boiling point.
Evaporation - vaporization of an uncontained liquid ( no lid on the bottle ).

4. Evaporation Molecules at the surface break away and become gas.
Only those with enough KE escape
Evaporation is a cooling process.
It requires energy.

5. Boiling vapor pressure = the external pressure
Temperature is called the boiling point
Normal Boiling point is the temperature a substance boils at 1 atm pressure.
The temperature of a liquid can never rise above it’s boiling point
Energy goes into breaking forces, not moving faster.

6. Changing the Boiling Point
Lower the pressure (going up into the mountains).
Lower external pressure requires lower vapor pressure.
Easier to make bubbles

7. Changing the Boiling Point
Raise the external pressure (Use a pressure cooker)
Raises the vapor pressure needed.
Harder to make bubbles
Raises the boiling point.

8. Different Boiling points
Different substances boil at different temperatures because they have different intermolecular forces
Weak forces- lower boiling point

9. Gas to Liquid Phase Change
Condensation
Molecules stick together
Releases energy.

10. Dynamic equilibrium Can occurs between condensation and evaporation
1. When first sealed the molecules gradually escape the surface of the liquid

11. Dynamic equilibrium
2. As the molecules build up above the liquid some condense back to a liquid.

12. Dynamic equilibrium
3. As time goes by the rate of vaporization remains constant
4. but the rate of condensation increases because there are more molecules to condense.

13. Dynamic equilibrium Rate of Vaporization = Rate of Condensation
5. Equilibrium is reached when
Rate of Vaporization = Rate of Condensation
Molecules are constantly changing phase “Dynamic”
The amount of liquid and vapor remains constant “Equilibrium”

14. Vapor Pressure
In a closed container the gas molecules will cause pressure.
The pressure at equilibrium is called vapor pressure
Different compounds have different vapor pressures because of different intermolecular forces
Stronger forces, lower vapor pressure

15. Boiling/Evaporation (Vaporization) Liquid
Critical Point
Freezing
Condensation
Melting
Boiling/Evaporation (Vaporization)
Liquid
101.3 (kPa)
Pressure (kPa)
Normal Melting Point. (Tm)
Normal Boiling Point. (Tb)
Triple Point (All 3 states of Matter exist)
Solid
Gas
Deposition
Sublimation
Temperature (°C)

16. Triple Point ~ point on a phase diagram that represents all three phases
Normal Melting Point ~ melting point of a solid at a pressure of kPa or 1atm
Normal Boling Pont ~ boiling point of a liquid at a pressure of kPa or 1atm
Critical Point ~ distinction between the liquid and gaseous phases is almost non-existent

17. TP of Water

18. Triple Point CO2

19. TP Iodine

20. Sublimation

22. Gas
Condenses
Boiling
Freezing
Liquid
Melting
Solid
Energy is put in from solid to gas (warms)
Energy is removed from gas to solid (Cools)

23. Phase Diagrams Pressure ( atm) Temperature (°C) Solid/liquid
Liquid/gas
Solid/gas
Temperature (°C)