## Which ion will be oxidized/reduced?

$\Delta G^{\circ} = -nFE_{cell}^{\circ}$

klarratt2
Posts: 60
Joined: Fri Sep 28, 2018 12:16 am

### Which ion will be oxidized/reduced?

If we are just given which ions are used in the reaction, how would we be able to tell which one is oxidized and which is reduced? For example, if a question just told us we had Cu^2+ and Zn^2+, how would we know that Cu is reduced and the Zn^2+ has been oxidized?

A De Castro 14B 2H
Posts: 75
Joined: Fri Sep 28, 2018 12:29 am

### Re: Which ion will be oxidized/reduced?

One can tell which ion will be oxidized or reduced based on their standard reduction potentials, E°. A solution with a more positive reduction potential will tend to gain electrons (i.e. to be reduced by oxidizing the new species). Meanwhile, a solution with a more negative reduction potential will tend to lose electrons (i.e. to be oxidized by reducing the new species).

In your question, E°(Cu2+) = +0.339 V while E°(Zn2+) = -0.762 V. Since E°(Zn2+) is more negative than E°(Cu2+), Zn2+ has been oxidized.