why is fe 2+ a better reducing agent then mn2+. ( I thought since mn2+ had a higher Eox it would be better)

I looked up

Fe^+2 ==> Fe^+3 + e. Loss of electrons is oxidation so Fe+2 is being oxidized; therefore it is the reducing agent.
Mn^+2 ==> Mn(IV) + 2e
Fe = -0.77
Mn = -1.24
Therefore, Fe is the more positive value so it's better.

The reducing power of an element or ion can be determined by looking at its standard electrode potential (E°). When comparing the reducing abilities of Fe2+ and Mn2+, it is important to consider their respective standard electrode potentials.

At first glance, you might think that Mn2+ would be a better reducing agent since it has a higher E° value compared to Fe2+. However, it's crucial to remember that the electrode potential is the measure of the tendency of an element or ion to undergo reduction.

In the case of Fe2+, it has a lower E° value than Mn2+, indicating that it is less likely to undergo reduction (gain electrons) compared to Mn2+. This means that Fe2+ has a greater tendency to be oxidized (lose electrons) and act as a reducing agent.

To understand why this is the case, we should consider the correlation between electrode potentials and the relative strengths of oxidizing and reducing agents. A higher E° value suggests a greater tendency for an ion to undergo reduction, making it a stronger oxidizing agent but a weaker reducing agent. Conversely, a lower E° value suggests a greater tendency to undergo oxidation, making it a stronger reducing agent and a weaker oxidizing agent.

Therefore, even though Mn2+ has a higher E° value than Fe2+, Fe2+ is a better reducing agent because it has a greater tendency to undergo oxidation and donate electrons, which is the characteristic of a good reducing agent.