1. Solids and Liquids
Chapter 14
Chem B

2. Condensed States
Attractive forces (interparticle) cause matter to hold together as liquids or solids
Gases – particles are spread out and very fast – attractions minimized by motion
When temp. drops, molecules SLOW and….

3. Condense – change from gas to liquid
Because the attractions between molecules become greater.
Particles start sticking together…liquid

4. Particles compared

5. Vaporization Opposite of condensation
Boiling and evaporation - two types
Boiling – details later
Evaporation – happens only at surface and to highest energy molecules (they escape!)
- leaves lower energy particles behind – this means lower temp. (cooling via sweat)

6. Liquids and Solids
Liquid particles slide past each other, but are close together.
Solids have stronger attractions. Particles go slower and get “locked” into a crystal lattice.
Motion is vibrational, not free.
Freezing is change from liquid to solid
Melting is opposite of freezing.

7. Liquid and Solid

8. Sublimation Change from solid directly to gas.
Dry ice is best example. Ice and iodine also.
Deposition is opposite process.

9. Crystalline Solids Particles in fixed, orderly, repeating pattern.
Crystal Lattice
Usually higher energy needed to break up
Means higher MP
Bonding in all directions
Most solids including salt, sugar, and all solid metals

10. Amorphous Solids Wax, Glass, and some plastics
Particles are randomly arranged, not evenly spaced.
Melting point is not sharply defined

11. Vapor Pressure
In a closed container all liquids will have some evaporation
This produces vapor pressure.
Amount depends on the temp. and the type of liquid
Nonpolar substances have highest VP
High temp. gives high VP

12. Vapor pressure curve graph

13. Boiling Boiling is the liquid to gas phase change
Occurs when the VP = atmospheric pressure
Boiling point is the temp. when VP = Standard Pressure

14. Boiling can happen at different Temperatures
Change the vapor pressure.
Pressure cookers (higher BP)
Demo…..?

15. KE and PE in phase changes
During a phase change, temperature remains constant →KE constant, PE changes
Energy is used to change arrangements of particles not speed.
During heating/cooling, temperature changes → KE changes, PE is constant

16. Heating Curve for Water
and Ice
Ice
Water and Steam
Steam
-20 20 40 60 80
100
120
220
760
800
Heating Curve for Water
PE change
KE Change
KE Change
Temp C
PE change
KE Change
Time

17. Calculating energy changes
Three equations:
1. For temp. change: ΔH= mCΔT
2. For liquid-solid change ΔH = m ΔHfus
3. For liquid-gas change ΔH = m ΔHvap
In all these ΔH is the energy change; m is mass; ΔT is temp change
Other values are constants.

18. Phase diagrams