Cell potential equation

[Clinicall]

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[Czarcasm]

So I always thought that Ecell= Ecathode - Eanode, however I'm finding the equation that the cell potential = oxidizing potential + reducing potential. Are these two different equations or am I missing something subtle here.

It means the same thing, just how you decide to use it. Personally, I use the second as it's more intuitive and avoids careless mistakes.

Let's say you're given a list of reduction half reaction potentials. For the cathode, you take the E cell potential as written (since it's the site of reduction). For the anode (site of oxidation), we reverse the sign of the reduction half reaction. When you do this, the total cell potential is just the sum of both values.

The first equation is a bit lazier, less intuitive version. All you're essentially doing is subtracting the reduction potential value for the Eanode to make it positive, but chances are you'll switch the sign and then try to subtract it ...which would just be wrong. 😉