How can iron(III) ions be reduced to iron(II) ions?

Iron(III) ions (${\text{Fe}}^{3+}$) can be reduced to iron(II) ions (${\text{Fe}}^{2+}$) through the process of oxidation-reduction, which involves the transfer of an electron to the iron(III) ion.1

This reduction is a characteristic reaction of the iron system and can be achieved using a wide variety of reducing agents. In chemical terms, this process is represented by the following half reaction:

$${\text{Fe}}^{3+}(aq)+e^{-}\to {\text{Fe}}^{2+}(aq)$$

The symbol $e^{-}$ represents the electron provided by an unspecified reducing agent required to facilitate the change. Experimentally, such reactions can occur through different mechanisms, such as outer-sphere reactions, where electron transfer happens without breaking bonds between the metal and its surrounding molecules, or inner-sphere reactions, where the metals share a common bridging group during the transfer process.12