The quiz next week will be given during your recitation.

1. The quiz next week will be given during your recitation. It will cover material starting with section 10.7. First Midquarter Exam Monday, Jan 29 6:30-7:48 pm Rooms TBA Chaps 10, 11, 13 Dr. Zellmer’s web site has very useful information on BP data and the use of Excel for Exps. 13 and 17.

2. 11.5 Vapor Pressure • Explaining Vapor Pressure on the Molecular Level, Volatility, • Vapor Pressure, and Temperature; • Vapor Pressure and Boiling Point • 11.6 Phase Diagrams • The Phase Diagrams of H2O and CO2 • 11.7 Structures of Solids • Unit Cells • The Crystal Structure of Sodium Chloride • Close Packing of Spheres • 11.8 Bonding in Solids • Molecular Solids • Covalent-Network Solids • Ionic Solids • Metallic Solids • Chapter 13 Properties of Solutions • 13.1 The Solution Process • Energy Changes and Solution Formation • Solution Formation, Spontaneity, and Disorder • Solution Formation and Chemical Reactions

4. But, recall, we always prefer straight lines! (Add slide of C-C eq and plot.) ←Temp. increases

5. Using the Clausius-Clapeyron Equation: Tabulate P in atm and T in K; Calculate lnP and 1/T Plot lnP vs 1/T The slope is = - ΔHvap /R The slope!

6. Phase Diagrams

8. The Critical Point:

10. Example Question on Phase Diagrams 11.55 The normal melting and boiling points of xenon are -112 oC and -107 oC, respectively. Its triple point is at -121 oC and 282 torr, and its critical point is a 16.6 oC and 57.6 atm. (a) Sketch the phase diagram of Xe, showing the four points given above and indicating the area in which each phase is stable. (b) Which is more dense, solid or liquid Xe? (c) If Xe gas is cooled under an external pressure of 100 torr, will it undergo condensation or deposition?

11. 11.7 Structures of Solids • Unit Cells • The Crystal Structure of NaCl • Close Packing of Spheres • 11.8 Bonding in Solids • Molecular Solids • Covalent-Network Solids • Ionic Solids • Metallic Solids

12. Sulfur Crystals

13. Millerite Crystals (a nickel ore)

14. Some interesting web sites: See the Carmen site for excellent discussion of your XRD Experiment (X-Ray Diffraction experiment) Research Experiences to Enhance Learning (Ohio REEL) Ice and Snow Crystals at Cal Tech web site Univ. of PA discussion of XRD Youngstown State Univ. XRD Lab

15. Solids • We can think of solids as falling into two groups: • Crystalline—particles are in highly ordered arrangement.

16. Solids • Amorphous—no particular order in the arrangement of particles.

19. These are the ones we’ll be interested in. These are the ones we’ll be interested in. ↓

21. Bravais Lattice Type = P (primitive)

22. Bravais Lattice Type = I (body centered)

23. Bravais Lattice Type = F (face centered)

29. Crystallographic ‘Planes’ and Miller Indices A plane that intercepts the a-axis at a/h,the b-axis at b/k, and the c-axis at c/l is known as an hkl plane, where hkl are the Miller indices. Alternatively, you can get the Miller indices by counting the number of times the plane crosses each axis within a unit cell for each direction.

31. Now back to some discussions of unit cells.

33. The ‘NaCl’ Structure

34. An alternate view of the NaCl Structure

38. The quiz next week will be given during your recitation. It will cover material starting with section 10.7. First Midquarter Exam Monday, Jan 29 6:30-7:48 pm Rooms TBA Chaps 10, 11, 13 Dr. Zellmer’s web site has very useful information on BP data and the use of Excel for Exps. 13 and 17.

39. Miller Indices in 3D The distance between planes is given by the following formula (for an orthorhombic lattice): 1/d2 = h2/a2 + k2/b2 + l2/c2 For a cubic lattice this reduces to: 1/d2 = (h2 + k2 + l2)/a2 Plane that goes through the origin The next plane is the one used to calculate hkl In a 3D system there are three Miller Indices, h, k and l. The values of h, k and l are integers whose values are determined as follows: h = 1/(x-intercept) h = a/(1a) = 1 k = 1/(y-intercept) k = b/(1b) = 1 l = 1/(z-intercept) l = c/() = 0 110 plane

40. 30 50 60 20 20 40 2-Theta (Degrees) X-Ray Powder Pattern There are many different planes of atoms in a crystal. In an X-ray powder diffraction pattern we see many peaks, each one corresponding to scattering from different planes of atoms. The numbers in the above diagram are called Miller Indices, they identify different planes of atoms in the crystal.

41. X-Ray Powder Diffraction Pattern (Lead Sulfide, PbS) 020 planes 220 planes Each peak corresponds to scattering from a different set of lattice planes. Two planes are shown above for PbS, which has the same structure as NaCl.

45. fact Cubic close packing (ABCABC..) Hexagonal close packing (ABABAB…)

47. Hexagonal Close Packing (ABAB…) ABAB Stacking Cubic Close Packing (ABCABC…) ABCABC Stacking Cubic and Hexagonal Close Packing

48. Coordination Environment (Close Packed Structures) Cubic Close Packing B C B A B A Hexagonal Close Packing Each atom has 12 nearest neighbors in both structures

49. (a) (b) (c) HCP Unit Cell (ABAB…) Hexagonal close packed structures adopt a hexagonal unit cell, as shown above. For every lattice point there are two atoms displaced from the lattice point by the following vectors: Atom 1: 1/3a + 2/3b + 1/4c Atom 2: 2/3a + 1/3b + 3/4c

50. (a) (b) CCP Unit Cell (ABCABC…) Cubic close packed structures adopt a face centered cubic (fcc) unit cell. The layers stack perpendicular to the body diagonal of the unit cell. C B A A C B A A