[THC]

This is somewhat of a newbie question, but I haven't been able to find a clear answer.

Example:
An electrochemical cell consists of two half cells. All the solutions are 1 M. The two half reactions are
Fe2+ + 2 e- -> Fe
Eo = -0,44 V

Ag+ + e- -> Ag
Eo = 0,80 V

So the spontaneous reaction is
2 Ag+ + Fe -> 2 Ag + Fe2+

How do calculate E_cell for this? Since the half reaction really is Fe -> Fe2+ + 2 e-, and not the reverse, why shouldn't I use Eo(Fe|Fe2+) = 0,44 V?

[enahs]

Consistency and definition.

The electrode potential is defined as:
E= E₊ - E_-

But those electrode potentials are the reduction potentials ONLY. If you reverse the direction and the potential, you no longer have the reduction potential value.

That is how we define it. There is not even an empirical zero point, we chose an arbitrary zero point.

[THC]

Consistency and definition.

The electrode potential is defined as:
E= E₊ - E_-

But those electrode potentials are the reduction potentials ONLY. If you reverse the direction and the potential, you no longer have the reduction potential value.

That is how we define it. There is not even an empirical zero point, we chose an arbitrary zero point.

So the 0.44 V for the reverse reaction has no significant physical meaning? It isn't used in ANY context?