chem test 1

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chem test 1
2011-07-13 17:59:38
nyu chemistry genchem2

Chemistry 2 Flash Cards - Test 1
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  1. the amount of energy required to increase teh surface area by one area unit
    • surface tension (J/m2)
    • hydrogen bonding leads to higher surface tension
  2. the intermolecular forces acting between its own particules that tend to hold the liquid together
    cohesive forces
  3. the intermolecular ineractions between the partciles of a liquid and those of a solid surface
    adhesive forces
  4. capillary action occurs when...
    adhesive forces are stronger than cohesive forces
  5. resistance to flow
  6. a more viscous liquid has...
    • stronger intermolecular forces
    • long chain-like molecules
  7. important facts about water:
    • high heat capacity
    • high melting point
    • high boiling point
    • large enthalpy of vaporization
    • large enthalpy of fusion
    • utility as a solvent
    • solid form is less dense than its liquid form
    • (consequences of the very polar/hydrogen bonding nature)
  8. crystalline solid
    the pattern of fixed particule positions is regular and the pttern is repeated throughout the solid
  9. amorphous solid
    the particle positions are fixed but without a regular, repating pattern
  10. unit cell
    for a crystalline solid, a single instance of the repeating pattern
  11. lattice points
    locations occupied by particules that define the unit cell (atoms, molecules, or ions)
  12. cubic crystal facts:
    • each cubic unit cell is face to face adjacent to six other unit cells in a crystal lattice
    • a single atom or ion at the periphery of one cell will extend into adjacent cells
    • a particule located that the corner of a cubic unit cell extends equally into eight cells; each corner particule contributes 1/8th of a particle to the occupation of a given cell
  13. simple cubic cell (sc)
    • only has corner particles
    • only contains one particle
    • a = 2r
    • 52% packing efficiency
  14. body-centered cubic (bcc) cell
    • lies completely within the cell
    • contains two particles (center particule and the eight eights of the corner particles)
    • a = (4/square root of 3) x r
    • 68% packing efficiency
  15. face-ceneterd cubic (fcc) cell
    • lies half within one cell and half within another cell
    • contains 4 particules (3 "face" particles and the eight eights of the corner particle)
    • also known as "ccp"
    • a = (square root of 8) (r)
    • r = (square root of 2) (a) / 4
    • 74% packing efficiency
    • same packng eficiency as hexagonal closest packing (hcp)
  16. coordination number
    • the number of neighbors in contact with a given particle
    • the higher the coordination number, the less empty space in the crystal
  17. packing efficiency
    • percent of the lattice which is actually occupied by particles
    • (V occupied/V total) (100)
  18. volume of an atom
    4/3 pi r3
  19. atomic and molecular solids
    • held in place by intermolecular forces
    • soft
    • low melting points
    • poor conductors of heat and electrical current
  20. network covalent solids
    • held in place by covalent bonds
    • 3-dimensions: crystal is strong (diamond)
    • 2-dimensional: strong layers held weakly togther by dispersion forces (graphite)
    • poor conductors of heat and electrical current
  21. ionic solids
    • includes a cation and an anion held in place by ionic bonds
    • strong
    • hard
    • high melting points
    • poor conductors of heat and electrical current in crystalline form
    • good conductors when melted
  22. metallic solids
    • good conductors of heat and electical current
    • strength and rigidity vary greatly
  23. molar enthalpy of vaporization
    the amount of thermal energy that must be added to a 1 mole sample of a liquid at its boiling point in order to convert it to 1 mole of gas at that same temperature
  24. molar enthalpy of fusion
    the amount of thermal energy required to melt 1 mole of a solid at its melting point
  25. Clausius-Clapeyron equation
    • ln P2/P1 = -Hvap/R (1/T2 - 1/T1)
    • remember T must be in kelvins!