Chemistry Chapter 12 pt 1

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Chemistry Chapter 12 pt 1
2015-08-26 20:39:06
Chemistry Wake Tech Chapter 12

Wake Tech Chemistry 152
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  1. Intermolecular Forces (IMF)
    attractive forces that hold particles together in the condensed phases (the magnitude determines s,l,g)

    solid high IMF gas low IMF 

    These forces are known as Vander Waal forces
  2. intermolecular
    between 2 molecules
  3. intramolecular
    within the same molecule
  4. Types of Vander Waal forces
    • Dipole-Dipole
    • Dispersion aka London Dispersion
    • Hydrogen Bonding 
    • Ion Dipole
  5. Dipole Dipole
    attractive fores that act between POLAR molecules

    Sort of act like a magnet. The magnitude of attractive forces depend on magnitude of dipole
  6. Polar vs nonpolar vs ionic
    look at difference in charges

    • if <.4 nonpolar convalent 
    • if .05 - 1.7 polar covalent 
    • if > 1.8 ionic
  7. Dispersion
    occurs with NONPOLAR molecules
  8. Dipole Moment
    Μ=Qd (Q the difference?)

    higher dipole moment, higher boiling point
  9. Hydrogen Bonding
    • Special type of dipole dipole interactions
    • Only occurs in molecules that contain H and highly electronegative atoms 
    • N,O, or F

    • High IMF means higher BP because need more E to break bonds 
    • (also Cl, Br, I but those are technically dipole)
  10. Intramolecular
    • think of Antifreeze
    • it's the attraction of positive and negative within the SAME molecule
  11. AS molar mass increases...
    BP increases linearly with the exception of molecules with hydrogen bonding
  12. Dispersion forces aka London dispersion forces
    result from Coulumb (mass to mass ratio of electron) attractions between INSTANTANEOUS DIPOLES of non polar molecules

    weakest bond

    larger molecule = larger dispersion force
  13. Surface Tension
    amount of energy required to stretch or increase the surface of a liquid of a nit area

    create a skin which is what allows bugs to walk on water

    stronger intermoleculer forces means higher surface tension
  14. Capillary action
    movement of liquid up and down a narrow tube

    cohesion and adhesion
  15. Cohesion
    between LIKE molecules

    greater in mercury which is why we have the hump in test tube
  16. Adhesion
    between UNLIKE molecules

    greater force in H2O which is why we have meniscus
  17. Viscosity
    a liquids resistance to flow

    • higher = moves slower
    • higher temp = lower viscosity
    • shear sensitive = shaking it/adding pressure makes it flow faster 
    • higher inter-molecular force = higher viscosity
  18. Higher surface area means
    more contact with other molecules
  19. inter vs intra molecular structures
    inter can go on having bonds with other molecules making it harder to break where as intra locks with itself