I have a question.
For Fe|Fe^+2 (1M)| Cu|Cu^+2 (1M
why did you use Fe^2+ ==> Fe^3+ + e Eo = -0.771 ?
instead of: Fe ---> Fe^+2 + 2e ?
thank you..
I have used the Fe^2+ ==> Fe^3+ + e so many times it is force of habit. I just screwed up. It should be Fe ==> Fe^2+ + e. But note that I would write the cell as
Fe|Fe^2+(1M) || Cu^2+(1M)|Cu
the cell is written like that in the report sheet so that's why I wrote it like that
The reason we use the reaction Fe^2+ ==> Fe^3+ + e Eo = -0.771 instead of Fe ---> Fe^+2 + 2e is because the given reaction involves the Fe^2+ and Fe^+3 ions, not the Fe and Fe^+2 ions.
To better understand why we use the Fe^2+ to Fe^3+ reaction, let's break it down.
In the given reaction, we have Fe|Fe^+2 (1M) which means there is an electrode composed of metallic iron (Fe) in contact with an aqueous solution containing Fe^+2 ions. Similarly, we have Cu|Cu^+2 (1M), which indicates an electrode made of metallic copper (Cu) in contact with an aqueous solution containing Cu^+2 ions.
The standard reduction potential, Eo, is a measure of the tendency of a substance to gain electrons. In this case, we want to find the standard reduction potential for the Fe^2+ to Fe^3+ reaction. The value Eo = -0.771V represents the reduction potential for this reaction, indicating a higher tendency for Fe^2+ ions to be oxidized (lose electrons) to form Fe^3+ ions.
By using the reduction potential Eo = -0.771V, we can compare it with the Cu^2+ to Cu^+ reaction to determine the direction of electron flow in the cell. In this case, Fe^2+ is more likely to get oxidized than Cu^2+. So, electrons will flow from the Fe electrode (anode) to the Cu electrode (cathode).
In summary, the given reaction involves the Fe^2+ to Fe^3+ reaction because we are considering the reduction potential of Fe^2+ and comparing it to Cu^2+ to determine the direction of electron flow in the cell.