Exploring Intermolecular Forces & Phase Changes in Molecules

1. Chapter 11 – Molecule Love

2. 11.1 Comparison of liquid & Solids • (Table 11.1) • 11.2 • Intermolecular (attractive) Forces • A. ion-ion  ionic (duh.), high MP • (strongest) • B. ion-dipole  salt water • C. dipole-dipole  2 polar molecules

3. Continued… D. dipole-induced-dipole  1 polar and 1 non-polar molecule E. London Dispersion Forces  2 non-polar molecules (LDF) weakest

4. F. Hydrogen Bonding  H bonded with N, O, & F • from high electronegativity ( H2O, NH3, HF) • 1. Ice expands when freezes • 2. Ice is less dense than H2O • 3. All snowflakes are 6-sided

10. G. Sample~> • Arrange in increasing BP • BaCl2, H2, CO, HF, Ne • H2 • Ne • CO • HF • BaCl2

11. 11.3Properties of Liquids • Viscosity- Ability to “go with the flow” • Surface tension – imbalance of forces at the surface of a liquid • Capillary rise – when a liquid adheres to the walls of a tube • Adhesive forces- stick to something else • Cohesive forces- stick to itself • Meniscus- curve in a liquid

12. Surface tension

13. Capillary rise

15. Water Hg

16. Meniscus – Greek for crescent

18. 11.4 Things heat up • Phase Changes • Gas • Liquid • Solid endo exo Solid to Gas: Subliming Gas to Solid: Deposition Solid to Liquid: Melting Gas to Liquid: Condensation Liquid to Gas: Evaporation Liquid to Solid: Freezing

19. EVAPORATION IS A COOLING PROCESS. • KE = ½ mv2 • Temp αAvg KE of the molecules.

20. II. Heating Curve 100o Heat of vaporization 0o Heat of fusion time

21. H20 HEAT OF FUSION : 6.01 kJ/mol (334 J/g) HEAT OF VAPORIZATION : 40.67 kJ/mol (2260 J/g) Sample 11.4 (YES. This will be on the test) q= mCp T = (18.0g)(2.09 J/g-K)(25o) = 940.5 J = (18.0g)(4.18 J/g-K)(100o) = 7524 J = (18.0g)(1.84 J/g-K)(25o) = 828 J 9292.5 J = (1 mol)(6.01 kJ/mol) = 6.01 kJ = (1 mol)(40.67 kJ/mol) = 40.67 kJ 46.68 kJ

22. 11.5 Vapor Pressure – pressure of a liquid that has evaporated • Dynamic equilibrium – 2 opposite process are occurring simultaneously at equal rates • Volatile – evaporates readily • Normal boiling point – BP at 1 atm ( sea level) • 11.6 Phase Diagrams 1 atm Press. solid liquid gas temp

23. Vacuum pump

27. Pressure cooker

28. Critical temp– highest temp at which a substance can exist as a liquid • Critical pressure– pressure required to bring liquid at this temp • Triple point– all 3 phases in equilibrium

29. 11.7 • Structure of Solids • A. Crystalline solid– regular repeating pattern • B. Amorphous solid– no repeating patterns

30. II. Unit Cells– repeating unit of solid • Simple cubic (8 dots) • Body-centered cubic (9 dots) • Face-centered cubic (14 dots)

31. III. Crystal Lattice– The most confusingly painful thing you’ll learn this year.

32. 11.8 Bonding in Solids (pg. 464) • Atomic – He • Molecular – Cl2 • Covalent-network – High MP, high MOH’s scale hardness • Ionic – SALT • Metallic -- sea of e-

33. The End

34. Allotropes – same element, different arrangement of atoms.graphite

35. diamond

36. Buckyball C60