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Phases of Matter Liquids, Solids (Crystals) & Solutions Colligative Properties

Intermolecular Forces I. Phases of Matter Liquids, Solids (Crystals) & Solutions Colligative Properties. Dr. Ron Rusay. Intermolecular Forces: Phases of Matter & Colligative Properties. Changes of State Phase transitions Phase Diagrams Liquid State

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Phases of Matter Liquids, Solids (Crystals) & Solutions Colligative Properties

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  1. Intermolecular Forces I Phases of Matter Liquids, Solids (Crystals) & SolutionsColligative Properties Dr. Ron Rusay

  2. Intermolecular Forces: Phases of Matter & Colligative Properties • Changes of State • Phase transitions • Phase Diagrams • Liquid State • Pure substances and colligative properties of solutions, which depend upon the ratio of the number of solute particles to the number of solvent molecules in a solution.They are independent of the nature of the solute particles.

  3. Intermolecular Forces: Phases of Matter • Solid State • Classification of Solids by Type of Attraction between Units • Crystalline solids; crystal lattices and unit cells • Structures of some crystalline solids • Determining the Crystal Structure by X-ray Diffraction

  4. Phase Transitions H2O(s)  H2O(l) H2O(l)  H2O(s) H2O(l)  H2O(g) H2O(s)  H2O(g) H2O(g)  H2O(l) H2O(g)  H2O(s) • Melting: change of a solid to a liquid. • Freezing: change a liquid to a solid. • Vaporization: change of a solid or liquid to a gas. Change of solid to vapor often called Sublimation. • Condensation: change of a gas to a liquid or solid. Change of a gas to a solid often called Deposition.

  5. Phases of Matter / Intermolecular Forces

  6. Phase Changes

  7. QUESTION

  8. B) crystallization As a substance crystallizes, generally from a liquid, but a gaseous starting point is possible, the molecules, atoms, or ions lose kinetic energy to allow for bonding. This kinetic energy is emitted as heat. ANSWER

  9. Bonds vs. Intermolecular Forces (150 - 1000 kJ/mol) (Ionic bond 700-4,000 kJ/mol) 16 kJ/mol 431 kJ/mol

  10. Intermolecular Forces • Ion-Dipole Forces(40-600 kJ/mol) • Interaction between an ion and a dipole (e.g. NaOH and water = 44 kJ/mol) • Strongest of all intermolecular forces.

  11. Intermolecular Forces Dipole-Dipole Forces (permanent dipoles) 5-25 kJ/mol

  12. Intermolecular Forces Dipole-Dipole Forces

  13. Intermolecular Forces • London or Dispersion Forces • An instantaneous dipole can induce another dipole in an adjacent molecule (or atom). • The forces between instantaneous dipoles are called London or Dispersion forces ( 0.05-40 kJ/mol).

  14. Intermolecular Forces London Dispersion Forces Which has the higher attractive force?

  15. Intermolecular Forces London Dispersion Forces

  16. Gecko: toe, setae, spatulae6000x Magnification Full et. al., Nature (2000) 5,000 setae / mm2 600x frictional force; 10-7 Newtons per seta Geim, Nature Materials (2003) Glue-free Adhesive 100 x 10 6 hairs/cm2 http://micro.magnet.fsu.edu/primer/java/electronmicroscopy/magnify1/index.html

  17. Boiling Points & Hydrogen Bonding

  18. Boiling Points & Hydrogen Bonding

  19. Hydrogen Bonding • Hydrogen bonds, a unique dipole-dipole (10-40 kJ/mol).

  20. QUESTION Which pure substances will not form hydrogen bonds? I) CH3CH2OH II) CH3OCH3 III) H3C−NH−CH3 IV) CH3F A) I and II B) I and III C) II and III D) II and IV

  21. ANSWER Which pure substances will not form hydrogen bonds? I) CH3CH2OH II) CH3OCH3 III) H3C−NH−CH3 IV) CH3F A) I and II B) I and III C) II and III D) II and IV

  22. Intermolecular Forces Hydrogen Bonding

  23. DNA: Size, Shape & Self Assembly http://www.umass.edu/microbio/chime/beta/pe_alpha/atlas/atlas.htm Views & Algorithms 10.85 Å 10.85 Å

  24. Intermolecular Forces

  25. Protein Shape: Forces, Bonds, Self Assembly, Folding Ion-dipole (Dissolving) 40-600kJ/mol 10-40kJ/mol 150-1000kJ/mol 0.05-40kJ/mol 700-4,000kJ/mol

  26. QUESTION • Predict which liquid will have the strongest intermolecular forces of attraction (neglect the small differences in molar masses). • A) CH3COCH2CH2CH3 (molar mass = 86 g/mol) • B) CH3CH2CH2CH2CH2OH (molar mass = 88 g/mol)   • C) CH3CH2CH2CH2CH2CH3 (molar mass = 86 g/mol) • D) HOH2C−CH=CH−CH2OH (molar mass = 88 g/mol)

  27. ANSWER • Predict which liquid will have the strongest intermolecular forces of attraction (neglect the small differences in molar masses). • A) CH3COCH2CH2CH3 (molar mass = 86 g/mol) • B) CH3CH2CH2CH2CH2OH (molar mass = 88 g/mol)   • C) CH3CH2CH2CH2CH2CH3 (molar mass = 86 g/mol) • D) HOH2C−CH=CH−CH2OH (molar mass = 88 g/mol)

  28. Vapor Pressure • Vapor Pressure on the Molecular Level Would water have a higher or lower vapor pressure @ the same temperature? (bp H2O > CH3CH2OH; bp = oC when Vapor Pressure = Atmospheric Pressure)

  29. Vapor Pressure Explaining Vapor Pressure on a Molecular Level

  30. Vapor Pressure • Volatility, Vapor Pressure, and Temperature

  31. Vapor Pressure • Solid Liquid Gas

  32. QUESTION

  33. E) The vapor pressure of a liquid. Molecules at the surface of a liquid will be held tighter by stronger intermolecular forces, making it more difficult for them to escape into the vapor phase. ANSWER

  34. Temperature & Vapor Pressure • The boiling point (b.p.) of a pure liquid is the temperature at which the vapor pressure above the liquid equals the external pressure. • Could water boil @ 0oC?

  35. Temperature Dependence of Vapor Pressures • The vapor pressure above the liquid varies exponentially with changes in the temperature. • The Clausius-Clapeyron equation shows how the vapor pressure and temperature are related. (R = 8.314 JK−1mol−1)

  36. Clausius – Clapeyron Equation • A straight line plot results when ln P vs. 1/T is plotted and has a slope of Hvap/R. • Clausius – Clapeyron equation is true for any two pairs of points.

  37. QUESTION

  38. D) diethyl ether, CH CH O CH CH Diethyl ether boils first as the temperature increases, leading one to believe that its vapor pressure at any temperature is also the highest of the given group of compounds. ANSWER – – 3 2 2 3

  39. Heating Curve http://chemconnections.org/general/movies/HeatingCurves.swf

  40. Energy (Heat) and Phase Changes • Heat of vaporization: heat needed for the vaporization of a liquid. H2O(l) H2O(g) DH = 40.7 kJ/mol • Heat of fusion: heat needed for the melting of a solid. H2O(s) H2O(l) DH = 6.01 kJ/mol • Temperature does not change during the change from one phase to another. 50.0 g of H2O(s) and 50.0 g of H2O(l) were mixed together at 0°C. Determine the heat required to heat this mixture to 100.0°C and evaporate half of the water.

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

  42. 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.

  43. Phase Diagrams

  44. Phase Diagrams

  45. 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

  46. 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

  47. Phase Changes Critical Temperature and Pressure

  48. 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

  49. 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

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