Chemistry Thermodynamics

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Anonymous
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74132
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Chemistry Thermodynamics
Updated:
2011-03-21 00:53:28
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chemistry thermodynamics exam
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Exam 2 Stuff
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  1. Heat (>, <, or = 0?)
    • If q>0, then heat is added to the system
    • If q<0, then heat is removed from the system
    • If q=0, then dU=w
  2. Work (> or < 0?)
    • If w>0, work is being done on the system.
    • If w<0, work is being done by the system.
  3. Internal Energy (dU) --> Any Conditions
    • dU = q + w
    • dU = ncv(dT)
  4. Heat --> General (Any Conditions)
    q = c(dT)
  5. Enthalpy Change --> Any Conditions
    • dH = dU + d(PV)
    • dH = ncp(dT)
  6. Work Against a Constant External Pressure
    w = -Pext(dV)
  7. Reversible, Isothermal Work
    w = -nRTln(V2/V1)
  8. Work at Constant Volume
    w = 0
  9. Relate cp and cv
    cp = cv + R
  10. Heat at Constant Volume
    • q = ncv(dT)
    • Note: This also equals dU, because at constant volume, w=0.
  11. Heat at Constant Pressure
    • q = ncp(dT)
    • Note: This also equals dH
  12. Enthalpy
    • A state function that represents the heat transferred for a system under constant pressure (qp)
    • dH = dU + d(PV)
    • For an ideal monatomic gas, this can be rewritten as: dH = dU + d(nRT)
    • dH = qp = ncp(dT)
  13. Molar Heat Capacities for Ideal, Monatomic Gases at Constant V and Constant P
    • cv = (3/2)R
    • cp = (5/2)R
  14. Boltzman's Equation
    • S = KBln(omega)
    • KB = 1.38 x 10-23 J/K
  15. Entropy Change for Reversible, Isothermal Expansion
    • dS = nRln(V2/V1)
    • dS = qrev/T
  16. Entropy Change at Constant Pressure
    dS = ncpln(T2/T1)
  17. Entropy Change at Constant Volume
    dS = ncvln(T2/T1)
  18. Entropy Change for Phase Changes
    dS = (dHPT)/T
  19. dSuniverse and Spontaneity
    • If dSuniv > 0, the process is spontaneous as written
    • If dSuniv < 0, the process is spontaneous in the reverse direction
    • If dSuniv = 0, the process is at equilibrium
  20. Gibbs Free Energy
    dG = dH - TdS

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