Chemistry Lect 3

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Chemistry Lect 3
2011-01-10 13:47:28

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  1. State Functions
    • Extensive: change with the amount (i.e. V, n)
    • Intensive: don't (i.e. P and Temp)
  2. Types of Heat Transfer
    • Conduction
    • Convection
    • Radiation (the only type of heat trans that travels through a vacuum)
  3. In which direction does heat travel?
    • From hot to cold
    • * remember that any energy transfer that is not heat is work!
  4. What kind of function is work?
    A pathway function - different pathways = different amounts of work
  5. Can a system at rest do work?
    A system at rest can still do PV work (must have a change in volume)
  6. First Law of Thermodynamics
    • ΔE = q + W
    • the change in energy is = to the heat flow into plus the work done on the system
  7. Second Law of Thermodynamics
    heat cannot be completely converted to work in a cyclical process
  8. Temp is related to:
    • how fast molecules are moving/vibrating
    • KEave = 3/2 KT
    • K: 1.38*10-23 J/K
  9. Pressure is what kind of property?
    • Intensive (does not change with amount)
    • the greater the KE/V the greater the pressure
  10. Enthalpy
    • ΔH = U + PV
    • if no change in volume than PV=0 and ΔH=U
    • ΔHRxn = ΔHProds - ΔHReactants
    • if ΔH is neg then the rxn is exothermic (releases heat)
  11. Entropy
    • tendency towards disorder
    • the more likely a situation is the more entropy it will have
    • on the MCAT a rxn must increase ΔSUniverse in order to proceed
    • rxns at equilibrium have reached max SUniverse
  12. Gibbs Free Energy
    • ΔG = ΔH - TΔS
    • an extensive property (changes with amount)
    • a neg G indicates an increase in ΔSUniverse and therefore is spontaneous
    • (-)ΔG and (-)ΔH = (+)ΔS --> spontaneous for sure