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Presenting - - -. http://www.uhd.edu/academic/colleges/sciences/naturalscience/BKC_Homepage.htm. Chemistry 1308 Fall 2008. Chapter 11 Intermolecular Forces: Liquids, Solids, and Phase Changes (A REVIEW!). 1. Intermolecular Attractive Forces 2. Phase Changes 3. The Liquid State

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  1. Presenting - - - http://www.uhd.edu/academic/colleges/sciences/naturalscience/BKC_Homepage.htm Chemistry 1308 Fall 2008

  2. Chapter 11Intermolecular Forces:Liquids, Solids, and Phase Changes (A REVIEW!) 1. Intermolecular Attractive Forces 2. Phase Changes 3. The Liquid State 4. The Solid State

  3. Intermolecular Attractive Forces Objective: To learn how intermolecular interactions effect (create) the various states of matter, particularly the liquid and solid states. Learning Goal: To become knowledgeable and con- versant about the fundamental interactions that occur among atoms, ions, and/or molecules and how these interactions determine the properties we observe for liquids and solids.

  4. The States of Matter Plasma Nuclei Electrons Gas Temperature Atoms or Molecules Liquid Atoms or Molecules Polymers And Liquid Crystals Crystalline Solid

  5. Intermolecular Attractive Forces Strongest Minimal Moderate Solid Liquid Gas

  6. Intermolecular Attractive Forces vs.Intramolecular Attractive Forces A Clarification! (Covalent Chemical Bond)

  7. Evidence of Intermolecular Attractive Forces Substances m.p. (K) b.p. (K) DHvap (kJ/mol) O2 CH4 H2C=O Br2 H2O Hg LiBr 54 91 181 166 273 234 823 90 112 252 332 373 630 1583 6.82 8.17 24.5 29.5 40.7 59.1 148.1

  8. Types of Intermolecular Attractive Forces: • Instantaneous Dipole-Induced Dipole Attractions (London Dispersion Forces) • Dipole-Dipole Attractions • Hydrogen Bonding • Ion-Dipole Attractions • Others???

  9. Instantaneous Dipole-Induced Dipole Interactions (London Dispersion Forces) Substances m.p. (K) b.p. (K) DHvap (kJ/mol) Noble Gases --- 24 84 116 160 He Ne Ar Kr Xe 4.2 27 87 121 166 0.081 1.76 6.52 9.03 12.63

  10. Instantaneous Dipole-Induced Dipole Interactions (London Dispersion Forces) Substances m.p. (K) b.p. (K) DHvap (kJ/mol) Halogens F2 Cl2 Br2 I2 50 172 266 387 85 239 332 458 6.5 20.4 29.5 41.9

  11. London Dispersion Forces + - + - Attraction • Due to instantaneous separation of charge in an atom or molecule. • Effective only at very short range. • Strength of force is dependent on the size of the atom or molecule and the number of electrons(Polarizability)

  12. Dipole-Dipole Attractions m Substances m.p. (K) b.p. (K) DHvap (kJ/mol) H2 Cl2 CH4 CH3Cl CH2Cl2 CHCl3 CCl4 CF4 14 170 90 176 177 209 250 89 20 239 111 249 313 335 350 145 0.90 20.4 8.17 21.5 28.1 29.2 29.8 12.0 D2 23.5 ????? 1.87 D 1.60 D 1.01 D 0.00 D

  13. Dipole-Dipole Attractions Cl H C Cl H Cl H C Cl H d - d + d - d + Attraction • Due to a permanent charge separation in the molecule. • Effective only at short to moderate range. • Strength of force is dependent on the relative electro- negativities of the atoms and the molecular geometry.

  14. Hydrogen Bonding (H-bonding) SnH4 Rn GeH4 Xe SiH4 Kr Relative Boiling Points CH4 Ar Ne He Molecular Mass

  15. Hydrogen Bonding (H-bonding) H2O H2Te HF H2Se H2S SbH3 Relative Boiling Points HI NH3 HCl AsH3 HBr PH3 Molecular Mass

  16. Hydrogen Bonding H H-N: H H H-N: H d + d - d + d - Attraction • Special case of dipole-dipole attraction. • Due to relatively large permanent charge separation in the molecule. • Effective at relatively long range. • Occurs when hydrogen is bound to a very electro- negative element (F, O, and N)

  17. Any Questions on Intermolecular Interactions??? Hydrogen Bonding Dipole-Dipole Attractions Instantaneous Dipole-Induced Dipole Attractions Ion-Induced Dipole Attractions Ion-Dipole Attractions

  18. Phase Changes Gas Deposition Evaporating Condensing Subliming Melting Liquid Solid Freezing

  19. Phase Changes X (s) -----> X (l) melting (fusion) - Endothermic X (l) -----> X (s) freezing - Exothermic X (l) -----> X (g) vaporization - Endothermic X (g) -----> X (l) condensation - Exothermic X (s) -----> X (g) sublimation - Endothermic X (g) -----> X (s) deposition - Exothermic

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