# chemistry

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A galvanic cell consists of a Mn/Mn^2+ electrode (E° = -1.18v) and a Fe/Fe^2+ electrode (E° = -0.44v). Calculate the ratio [Mn2+]/[Fe2+] if E_cell = .78v at 25°C.

I know to use the nernst eq.
E_cell = E°_cell - RT/nF * ln(Q)
where Q is the ratio I'm looking for and I a know all of the other #s except for how to find E°_cell?

• chemistry -

Mn==> Mn^2+ Eo = 1.18 (as written)
Fe^2+ ==> Fe Eo = -0.44 as written
--------------------------
Mn + Fe^2+ ==> Mn^2+ + Fe
Eocell = 1.18-0.44 = +0.74.

• chemistry -

Got it, thank you!

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