Phases of Matter / Phases Diagrams Solids (Crystals) & Solutions Colligative Properties

1. Intermolecular Forces II Phases of Matter / Phases Diagrams Solids (Crystals) & SolutionsColligative Properties Dr. Ron Rusay

2. Phase Diagrams • Graph of pressure-temperature relationship; describes when 1,2,3 or more phases are present and/or in equilibrium with each other. • Lines indicate equilibrium state between two phases. • Triple point- Temp. and press. where all three phases co-exist in equilibrium. • Critical temp.- Temp. where substance must always be gas, no matter what pressure. • Critical pressure- vapor pressure at critical temp. • Critical point- system is at its critical pressure and temp.

3. Phase Diagrams

4. Phase Diagrams

5. Phase Diagrams The Phase Diagrams of H2O and CO2 http://www.youtube.com/watch?v=OQPD4YBgeT8&feature=related http://www.youtube.com/watch?v=UVaPw9XzQ3g&feature=related http://www.youtube.com/watch?v=c2ZRwwHfC2c

6. Oscillatory Vapor-Liquid-Solid growth of sapphire nanowires (α-Al2O3) 660°C, Pressure= 10–6 Pa S. H. Oh et al., Science 330, 489-493 (2010) Published by AAAS

7. Phase Changes Critical Temperature and Pressure

8. Solutions Bonus: Explain how a 50:50 molar solution of molten potassium & sodium nitrates could be used to store solar energy. Archimedes’ Mirrors Freezing Point: 238°C Melting Point: 221°C Heat of Fusion: 161 kJ/kg

9. Solutions Bonus: Explain how a 50:50 molar solution of molten potassium & sodium nitrates could be used to store solar energy. Freezing Point: 238°C Melting Point: 221°C Heat of Fusion: 161 kJ/kg http://www.archimedesolarenergy.com/video3.htm

10. Solana Bonus: The heat from a solution of molten potassium & sodium nitrates is used to store the energy, which turns a turbine in 6 hrs of darkness/ day. $ 2 billion 3 years 2,200,000 m2 2,700 mirrors 280 MegaWatts 70,000 homes - 475,000 MT CO2 Equivalent http://www.youtube.com/watch/?v=G1hdoWk17wU

11. Solutions

12. QUESTION

13. Factors Affecting Solubility Concentration Gradients: Diffusion • Movement of molecules from an area of high concentration to an area of lower concentration. • Factors that affect the rate of diffusion: size of molecules, size of pores in membrane, temperature, pressure, and concentration. Osmosis • Osmosis is the movement of solvent across a semi-permeable membrane • Initially the concentration of solute is very high, but over time, the solvent moves across the semi-permeable membrane and dilutes the particles.

15. Osmosis – A Special kind of Diffusion Diffusion of water across a selectively permeable membrane (a barrier that allows some substances to pass but not others). The cell membrane is such a barrier. Small molecules pass through – eg. water Large molecules can’t pass through – eg. proteins and complex carbohydrates https://www.youtube.com/watch?v=sdiJtDRJQEc

16. Over time molecules move across the membrane until the concentration of solute is equal on both sides. This type of solution is called ISOTONIC.

17. Factors Affecting Solubility Pressure Effects If Sg is the solubility of a gas, k is a constant, and Pg is the partial pressure of a gas, then Henry’s Law gives:

18. QUESTION A minimum of 1.3  10–4 M O2 must be maintained in freshwater supplies to sustain aquatic life. In the mountains of Montana, the partial pressure of O2 may drop to 0.15 atm. What is the water concentration of O2 there? Henry’s constant for O2 = 1.3  10–3 mol/L-atm. At the lower elevations at the base of those mountains, would more or less O2 be dissolved in water? M = 2.0  10–4; more dissolved M = 8.7  10–4; more dissolved M = 2.0  10–4; less dissolved M = 8.7  10–4; less dissolved

19. Phase Diagrams for Pure Water (Red) and for an Aqueous Solution Containing a Nonvolatile Solute (Blues)

20. Sugar Dissolved in Water to Make Candy Causes the Boiling Point to be Elevated

21. Spreading Salt on a Highway The Addition of Antifreeze Lowers the Freezing Point of Water in a Car's Radiator

22. Colligative Properties • Colligative properties depend on quantity and type of solute/solvent molecules. (E.g. freezing point depression and melting point elevation.) • Lowering Vapor Pressure • Non-volatile solvents reduce the ability of the surface solvent molecules to escape the liquid. • Therefore, vapor pressure is lowered. • The amount of vapor pressure lowering depends on the amount of solute.

23. Colligative Properties • Lowering Vapor Pressure • Raoult’s Law: PA is the vapor pressure with solute, PA is the vapor pressure without solvent, and A is the mole fraction of A, then • Recall Dalton’s Law:

24. QUESTION

25. Concentration • molality and Molarity • Molality relates to colligative properties. • Converting between molarity (M) and molality (m) requires density. • Therefore Molarity and molality are most often not equal

26. QUESTION

27. Molal Boiling-Point Elevation Constants (Kb) and Freezing-Point Depression Constants (Kf) for Several Solvents

29. QUESTION Household bleach is an aqueous solution of sodium hypochlorite. If 5.25 g of NaOCl (molar mass = 74.5 g/mol) were placed in 94.75 g of water, what would you calculate as the molality? The density of the solution is slightly greater than water. Would the molarity of the solution be greater, less or the same as the molality? 0.0705 m; M would be greater 0.705 m; M would be the same 0.744 m; M would be greater 0.744 m; M would be less

30. QUESTION Suppose you want to keep the water in your car cooling system from freezing during a cold Alaska winter night. If you added 5.00 kg of ethylene glycol (C2H4(OH)2 MM = 62.0 g/mol) to 5.50 kg of water, what would be the freezing temperature of the coolant/water mixture in your automobile? k f.p. H2O = –1.86°C kg/ mol –0.0367°C –7.90°C –14.7°C –27.3°C

31. Atomic Solid / Ionic Solid / Molecular Solid

32. Structure of Solids Structure of Solids Types of solids: • Crystalline – a well defined arrangement of atoms; this arrangement is often seen on a macroscopic level. • Ionic solids – ionic bonds hold the solids in a regular three dimensional arrangement. Eg. “Galena”, lead sulfide ore http://en.wikipedia.org/wiki/Crystal_radio http://www.crystalradio.net/ • Molecular solid – solids like ice that are held together by intermolecular forces. • Covalent network– a solid consists of atoms held together in large networks or chains by covalent networks. Eg. Diamond & graphite • Metallic – similar to covalent network except with metals. Provides high conductivity. • Amorphous – atoms are randomly arranged. No order exists in the solid. Eg. Glass, gels, thin films

33. Closest Packing Arrangement of Uniform Spheres Arrays of atoms act as if they are spheres. Two or more layers produce a 3-D structure.

34. Close Packed: The Red Sphere has 12 Nearest Neighbors

35. Closest Packed Structure

36. Unit Cells • Crystals are made up regular arrays – the smallest repeating array of atoms is called the unit cell. • There are 14 different unit cells that are observed which vary in terms of the angles between atoms some are 90°, but others are not.

37. Unit Cells • Length of sides a, b, and c as well as angles a, b, g vary to give most of the unit cells.

38. QUESTION Cubic Hexoctahedral cF8, space group Fm3m, No. 225 Consider an interior atom in the simple cubic crystal lattice. What is the maximum number of unit cells that share this atom in the three-dimensional crystal lattice? A) 2 B) 4 C) 6 D) 8

39. Unit Cells • Simple-cubic • Body-centered cubic • Face-centered cubic

40. QUESTION The number of atoms per unit cell in the body-centered cubic lattice is A) 1 B) 2 C) 3 D) 4

41. Unit Cells • Face Centered Cubic structure has a-b-c-a-b-c stacking. It takes three layers to establish the repeating pattern and has 4 atoms per unit cell and the coordination number is 12.

42. The Net Number of Spheres in a Face-Centered Cubic Unit Cell

43. Unit Cells • Simple-cubic shared atoms are located only at each of the corners. 1 atom per unit cell. • Body-centered cubic 1 atom in center and the corner atoms give a net of 2 atoms per unit cell. • Face-centered cubic corner atoms plus half-atoms in each face give 4 atoms per unit cell.

44. Unit Cells Galena, lead sulfide Cubic Hexoctahedral cF8, space group Fm3m, No. 225 Can you hear anything?

45. Crystals for the ClassroomBridging the realms of the macro and atomic/nano scalehttp://crystals.llnl.gov Connecting: Science, Technology, Engineering and Mathematics (STEM)

46. Crystals for the ClassroomBridging the realms of the macro and atomic/nano scalehttp://crystals.llnl.gov The story of NIF ( The National Ignition Facility) http://crystals.llnl.gov/nif-kdp-frameset.html

47. Crystals for the ClassroomBridging the realms of the macro and atomic/nano scalehttp://crystals.llnl.gov Time lapsed KDP Growth

48. Crystals for the ClassroomBridging the realms of the macro and atomic/nano scalehttp://crystals.llnl.gov Simulation: Fusion

49. X-ray Crystallography http://info.bio.cmu.edu/courses/03231/ProtStruc/ProtStruc.htm Rosalind Franklin’s Photo 51 46 Å 12 base sequence (1953) http://molvis.sdsc.edu/pdb/dna_b_form.pdb

50. T. Sumner, Science, 1092-93 (2014)