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CHE 107 Chapter 9: Thermochemistry

  1. First law of Thermodyamics (formula):
    ΔEsys = q + w
  2. What is Δ order?
    final - inital
  3. General Formula for Work?
    W = F x d

    Work = Force x Distance
  4. Formula for PV or Expansion work that results from a volume change?
    w = -PΔV

    Do not forget the negative!
  5. If the volume of a system is fixed and the only work that can be done is PV work....
    • then.. 
    • w = 0
    • so...
    • ΔEsys = q
  6. If  reaction is done at constant atmospheric pressure...
    Δ(PV) ≠ 0
  7. What is H?
    • H: Enthalpy
    • Heat transferred between the system and surroundings carried out under constant pressure
  8. If ΔH > 0...
    If ΔH is (+)
    • If ΔH > 0...
    • If ΔH is (+)....

    • Endothermic
    • Absorbs heat
  9. If If ΔH < 0...
    If ΔH is (-)...
    • If If ΔH < 0...
    • If ΔH is (-)...

    • Exothermic
    • Releases heat
  10. Hess's Law
    • Switch a reaction -- reverse sign
    • Change factor -- multiply H by same factor
  11. ΔHfusion
    solid ⇒ liquid
  12. ΔHvaporization
    liquid ⇒ gas
  13. ΔHsublimation
    solid ⇒ gas
  14. Units for heat capacity
    Does NOT have mass
  15. Units for specific heat
    DO have mass
  16. Calorimetry formula
    q = mcΔT

    and atmospheric pressure is constant!
  17. Formula for Bomb Calorimetry
    qrxn = -CcalorimeterT
  18. How to do Hess's Law:
    Apply all the rules, then add all of the ΔH for the reaction.
  19. How to find ΔHsublimation
    Add heat of vaporization and fusion.
  20. Formula for Enthalpies of Fusion
    ΔH°rxn = ΔH°f(products) - ΔH°f(reactants)

    used to calculate enthalpies of reaction
  21. Formula for bond enthalpies
    ΔHrxn = ΣD(bonds broken) - ΣD(bonds formed)
  22. What is S:
    S: entropy

    The measure of disorder in a system
  23. If ΔS > 0
    If ΔS > 0

    Randomness increases
  24. For a reversible process, what does If ΔSuniv do?
    ΔSuniv = 0
  25. Gibbs free energy equation
    ΔGT = ΔH - TΔS
  26. If ΔG < 0...
    If ΔG < 0...

    the reaction is spontaneous
  27. If If ΔG = 0...
    If If ΔG = 0...

    The reaction is at equilibrium
  28. When does ΔG° = 0?
    • ΔG° = 0 
    • at the temperature where a reaction changes from non-spontaneous to spontaneous
  29. Following 
    ΔG° = 0 at the temperature where a reaction changes from non-spontaneous to spontaneous...
    T = ΔH° / ΔS°
Author
JustDoughnut
ID
312870
Card Set
CHE 107 Chapter 9: Thermochemistry
Description
Notecards for chapter nine of lecture slides
Updated

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