Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions Recall (ch. 8): Free energyconditions. Helmholtz...
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Transcript of Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions Recall (ch. 8): Free energyconditions. Helmholtz...
![Page 1: Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions Recall (ch. 8): Free energyconditions. Helmholtz F isothermal Enthalpy H constant pressure Gibbs G.](https://reader030.fdocuments.in/reader030/viewer/2022033019/56649e525503460f94b47a2f/html5/thumbnails/1.jpg)
Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions
Recall (ch. 8):
Free energy conditions . Helmholtz F isothermal Enthalpy H constant pressure Gibbs G const. pressure and temp
![Page 2: Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions Recall (ch. 8): Free energyconditions. Helmholtz F isothermal Enthalpy H constant pressure Gibbs G.](https://reader030.fdocuments.in/reader030/viewer/2022033019/56649e525503460f94b47a2f/html5/thumbnails/2.jpg)
Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions
Recall (ch. 8):
Free energy conditions . Helmholtz F isothermal Enthalpy H constant pressure Gibbs G const. pressure and temp
Recall (ch. 3)
pg. 68: “The Helmoltz free energy will be a minimum for a system S in thermal contact with a reservoir R
if the volume of the system is constant.”
![Page 3: Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions Recall (ch. 8): Free energyconditions. Helmholtz F isothermal Enthalpy H constant pressure Gibbs G.](https://reader030.fdocuments.in/reader030/viewer/2022033019/56649e525503460f94b47a2f/html5/thumbnails/3.jpg)
Chemical reactions (and other experiments) are often carried out at constant pressure and constant temperature:
Gibbs free energy
G(U,P,V) = U – + PV(Gibbs free energy;Thermodynamic potential)
![Page 4: Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions Recall (ch. 8): Free energyconditions. Helmholtz F isothermal Enthalpy H constant pressure Gibbs G.](https://reader030.fdocuments.in/reader030/viewer/2022033019/56649e525503460f94b47a2f/html5/thumbnails/4.jpg)
Chemical reactions (and other experiments) are often carried out at constant pressure and constant temperature:
Gibbs free energy
G(U,P,V) = U – + PV
dG = dU – d – d + PdV + VdP
(Gibbs free energy;Thermodynamic potential)
![Page 5: Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions Recall (ch. 8): Free energyconditions. Helmholtz F isothermal Enthalpy H constant pressure Gibbs G.](https://reader030.fdocuments.in/reader030/viewer/2022033019/56649e525503460f94b47a2f/html5/thumbnails/5.jpg)
Chemical reactions (and other experiments) are often carried out at constant pressure and constant temperature:
Gibbs free energy
G(U,P,V) = U – + PV
dG = dU – d – d + PdV + VdP
(Gibbs free energy;Thermodynamic potential)
Isothermal dIsobaric dP = 0
So, for a system S at equilibrium:
dGS = dUS – dS + PdVS
![Page 6: Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions Recall (ch. 8): Free energyconditions. Helmholtz F isothermal Enthalpy H constant pressure Gibbs G.](https://reader030.fdocuments.in/reader030/viewer/2022033019/56649e525503460f94b47a2f/html5/thumbnails/6.jpg)
dG = 0 at equilibrium
Comparing to eqn. 5.39 (dUS = dS – PdVS + dNS) shows
dGS = dUS – dS + PdVS
dGS = dNS = 0, since dNS = 0 at
equilibrium
![Page 7: Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions Recall (ch. 8): Free energyconditions. Helmholtz F isothermal Enthalpy H constant pressure Gibbs G.](https://reader030.fdocuments.in/reader030/viewer/2022033019/56649e525503460f94b47a2f/html5/thumbnails/7.jpg)
Chemical reactions in equilibrium
H2 + Cl2 = 2HCl
1A1 + 2A2 + 3A3 + ….mAm = 0
A1 = H2 1 = 1 A2 = Cl2 1 = 1 A3 = HCl 1 = -2
jAj = 0
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Want to find expression of chemical equilibrium under conditions of constant temperature and pressure
dG = jdNj
The unknown details of the chemical reactions are summarized by the various chemical potentials.
j
Chemical reactions in equilibrium
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At equilibrium, dG = 0
Chemical reactions in equilibrium
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K(t) for an ideal gas with internal degrees of freedom
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K(t) for an ideal gas with internal degrees of freedom
![Page 12: Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions Recall (ch. 8): Free energyconditions. Helmholtz F isothermal Enthalpy H constant pressure Gibbs G.](https://reader030.fdocuments.in/reader030/viewer/2022033019/56649e525503460f94b47a2f/html5/thumbnails/12.jpg)
K(t) for an ideal gas with internal degrees of freedom
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K(t) for an ideal gas with internal degrees of freedom
![Page 14: Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions Recall (ch. 8): Free energyconditions. Helmholtz F isothermal Enthalpy H constant pressure Gibbs G.](https://reader030.fdocuments.in/reader030/viewer/2022033019/56649e525503460f94b47a2f/html5/thumbnails/14.jpg)
K(t) for an ideal gas with internal degrees of freedom
![Page 15: Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions Recall (ch. 8): Free energyconditions. Helmholtz F isothermal Enthalpy H constant pressure Gibbs G.](https://reader030.fdocuments.in/reader030/viewer/2022033019/56649e525503460f94b47a2f/html5/thumbnails/15.jpg)
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K(t) for an ideal gas with internal degrees of freedom
![Page 18: Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions Recall (ch. 8): Free energyconditions. Helmholtz F isothermal Enthalpy H constant pressure Gibbs G.](https://reader030.fdocuments.in/reader030/viewer/2022033019/56649e525503460f94b47a2f/html5/thumbnails/18.jpg)
K(t) for an ideal gas with internal degrees of freedom
![Page 19: Ch. 9 K&K: Gibbs Free Energy and Chemical Reactions Recall (ch. 8): Free energyconditions. Helmholtz F isothermal Enthalpy H constant pressure Gibbs G.](https://reader030.fdocuments.in/reader030/viewer/2022033019/56649e525503460f94b47a2f/html5/thumbnails/19.jpg)
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Chemical reaction rates