# Chemistry Thermodynamics

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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

### Card Set Information

 Author: Anonymous ID: 74132 Filename: Chemistry Thermodynamics Updated: 2011-03-21 04:53:28 Tags: chemistry thermodynamics exam Folders: Description: Exam 2 Stuff Show Answers:

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