(adsbygoogle = window.adsbygoogle || []).push({}); The redox midpoint potential (Eo’) of NAD+/NADH at pH 7.0 is -320 mV. If the total concentration of {[NAD+] + [NADH]} is 1.5 mM in cells, and the cellular redox potential is about -200 mV, what are the concentrations of [NAD+] and [NADH], respectively? Under certain oxidative stress conditions, the cellular redox potential is increased to -100 mV. What will be the concentrations of [NAD+] and [NADH] in this cell under the oxidative stress conditions? (Assume pH 7.0 is not changed under oxidative stress conditions).

Eh = Eo' - (RT/nF)ln(reduced/oxidized)but what does he mean by "oxidized," the molecule being oxidized (NADH) or what has been oxidized (NAD+)?

When I do this problem I keep getting an extremely small numbers that do me no good in the end; what am I doing wrong here? I'll just show the first part of the question (Eh = -200mV).

Eh = Eo' - (RT/nF)ln(reduced/oxidized)

Eh = -200E-3V, Eo' = -320E-3V

-200E-3V = -320E-3V - [(1.987E-3)(298)/(2)(23.1)]ln([red]/[ox])

120E-3V = (-0.01174)ln([red]/[ox])

-10.2 = ln([red]/[ox])

e^(-10.2) = [red]/[ox]

6.30957344E-11[ox] = [red]

[ox] + [red] = 1.5E-3M (total)

6.30957344E-11[ox] +[ox] = [red]

From here, because the coefficient for [ox] is so small I get [ox] = [red].

Any help is greatly appreciated!

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# Homework Help: Redox potential (Using the Nernst Equation)

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