Intermolecular Forces (l) & (s) phases: 1.Molecule-molecule 2.Molecule-ion

Suggested Reading: 1) Page 380, I suggest you read the first paragraph in section 8.8 if not the entire section. 2) Review Example 8.12 on pg 384 to make sense of why NH 3 is more polar than NF 3, which at first seems odd. 3) Read the bottom of pg 558 beginning with, “When a polar…” to “…dipole-dipole attraction.” 4) Read three paragraphs on pg 562, starting with “There is an unusually strong…” to “…(Figure 12.7).” 5) On pg , read the two sections: “Dipole/Induced Dipole Forces” and “London Dispersion Forces: Induced Dipole/Induced Dipole”.

12.1 Know the level of intermolecular forces for each state of matter, s, l, g. Which has the most and which has none?

PLAY MOVIE

Q: What makes molecules “stick” together in the liquid (and solid) state? A: The opposite ends of their dipoles: opposites attract…..and like polarities “stick” to like polarities.

Recall molecular polarity…?

Opposites attract…..and like polarities “stick” to like polarities.

Pg 563, Exc EOC 1, 3, 5, 7, 17

FORCES INVOLVING INDUCED DIPOLES Formation of a dipole in two nonpolar I 2 molecules. Induced dipole-induced dipole

PLAY MOVIE

FORCES INVOLVING INDUCED DIPOLES How can non-polar molecules such as O 2 and I 2 dissolve in water? The water dipole INDUCES a dipole in the O 2 electric cloud. Dipole-induced dipole

PLAY MOVIE

Different Levels of Molecular Polarity A D E B C H

PLAY MOVIE

Dipole-Dipole

H-Bonding

H-Bonding Between Two Methanol Molecules H-bondH-bond ---- ++++ ----

H-Bonding Between Methanol and Water H-bondH-bond ---- ++++ ----

H-Bonding Between Ammonia and Water H-bondH-bond ---- ++++ ----

Base-Pairing through H- Bonds

Hydrogen Bonding in Biology Hydrogen bonding and base pairing in DNA. See ChemistryNow, Chapter 12 PLAY MOVIE

Ion-Dipole

PLAY MOVIE

CH 4 C2H6C2H6C2H6C2H6 C3H8C3H8C3H8C3H8 C 4 H 10

Pg 563, Exc EOC 1, 3, 5, 7, 17

Boiling Liquids Liquid boils when its vapor pressure equals atmospheric pressure. PLAY MOVIE

4. If external P = 760 mm Hg, T of boiling is the NORMAL BOILING POINT 5. VP of a given molecule at a given T depends on IM forces. Here the VP’s are in the order C 2 H 5 H 5 C 2 H H 5 C 2 H H wateralcoholether increasing strength of IM interactions extensive H-bonds dipole- dipole O O O Liquids See Figure 12.17: VP versus T

From Chapter 13.6 Know how to interpret phase diagrams

Phase Diagrams

TRANSITIONS BETWEEN PHASES See Section 13.6 Lines connect all conditions of T and P where EQUILIBRIUM exists between the phases on either side of the line. (At equilibrium particles move from liquid to gas as fast as they move from gas to liquid, for example.)

Phase Equilibria — Water Solid-liquid Gas-Liquid Gas-Solid PLAY MOVIE Freezing/Melting Deposition/Sublimation Condensation/Evaporation

Phase Diagram for Water Solid phase Liquid phase Gas phase PLAY MOVIE

Triple Point — Water At the TRIPLE POINT all three phases are in equilibrium. PLAY MOVIE

CO 2 Phase Diagram

CO 2 Phases Separate phases Increasing pressure More pressure Supercritical CO 2 See Figure 13.20