1. Unit 8 - liquids and solutions

2. Phases of Matter Phases of Matter? Temperature dependence?
Phase Diagram -
P vs T
Triple point – point where all 3 phases are present (in equilibrium)
critical point – point at which no increase in pressure will condense the gas
normal bp & mp ( at 1 atm)

3. Phase Diagrams

4. Phase Diagram water

5. Phase Diagram carbon dioxide

6. Supercritical CO2 Video
water gas to solid - triple point Video

7. Heating Curve

8. Energy Changes Heating Curve
Molar heat of fusion – amount of energy needed to melt 1 mole of a substance
Heat of vaporization – amount of energy needed to vaporize 1 mole of a substance
Specific heat, Cp, – the amount of heat needed to raise 1 gram of a substance 1 oC
Q = m x Cp x DT

9. Intra vs Intermolecular Forces - why molecules stick together - and/or under what conditions
Intermolecular forces are those between molecules. Chemical bonds are intramolecular (within a molecule) forces. Intermolecular forces are as much as 5% of a chemical bond.
These forces determine what state of matter exists at room temperature.
What types of compounds are solids?
liquids? gases?

10. Intermolecular forces
What can cause molecules to stick to each other?
Molecules have what type of bonding?
Covalent bonding has atoms _____ electrons.
Do atoms share electrons equally?
What are molecules with unequally shared electrons?
Polar molecules have permanent dipoles.

11. Intermolecular forces - 3 types
Hydrogen bonding is strongest (actually just a special case of the dipole-dipole attraction.
Dipole-dipole attraction - polar molecules are attracted to each other, the positive charge of one molecule to the negative charge of another molecule
London Dispersion force is the weakest - non-polar molecules can have temporary dipoles

12. London dispersion force Balloon demo
- Occurs in all molecules! But only important in nonpolar molecules.
Caused by the motion
of electrons. The more electrons the larger the force.
F2 < Cl2 < Br2 < I2
The motion of e- s makes a non-uniform distribution - a temporary dipole.
This then induces a dipole on another molecule - and they are attracted to each other.
Balloon demo

13. dipole-dipole attraction

14. Hydrogen bonding in water

15. Hydrogen bonding in ice

16. Hydrogen bonding series graph

17. Evaporation & Vapor Pressure
Intermolecular forces have what affect on Vapor Pressure?

18. much higher, ionic are solids
Summary
Chapter 14
Intermolecular Forces (why molecules stick to each other)
Type
type of bonding
boiling / melting point
phase
examples
London-dispersion (LD) weakest
no permanent charge
nonpolar covalent
very low
gas
H2 Cl2
dipole-dipole (DD)
partial charge
polar covalent
a little higher than LD
gas or liquid
NO CF
Hydrogen bonding strongest
extreme polar covalent
higher than dipole
usually liquid
HO HN
Ionic - much stronger (not really intermolecular, but emphasizes importance of charge)
full charges on ions
ionic
much higher, ionic are solids
solid
NaCl K2O