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    Prediction of Changes to DeltaG in Non-Standard Cell

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    -438 kJ/mol is the free energy change of lactate oxidation by Fe3+ under non-standard conditions assuming that:

    C3H5O3- + 12 Fe3+ + 3 H2O -----> 3 CO2 + 11 H+ + 12 Fe2+

    [Fe2+]=10^-4 M
    T=25 degree centigrade
    [lactate]=10^-3 M
    Carbon dioxide is in equilibrium with atmospheric CO2
    Fe3+ is in equilibrium with Fe(OH)3 (s)
    Note for Fe(OH)3, Ksp=10^-38
    Ksp is the equilibrium constant

    Would the following changes make the overall free-energy change more or less favorblae for the overall reaction described above? (Indicate whether the free energy change is sensitive or insensitive to these differences by calculation of free energies):
    1. Raise pH of solution to 8.0
    2 . Lower Lactate activity to 10^-5 M
    3. Add FeCl3 while maintaining solution pH at 7.0
    4. Allow CO2 to build up in solution to equilibrate with 10^-2 atm CO2 while maintaining pH at 7.0
    5. Raise the solution temperature to 35 degree C. (Describe how this would be done, but please don't solve equations).

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    Solution Summary

    The solution shows how to analyze the effect of changing certain conditions on the free energy of a non-standard cell.