Final answer:
Iron hydroxide formation from Fe2+ and OH- is not an oxidation-reduction reaction because there is no electron transfer, and the oxidation state of iron does not change.
Step-by-step explanation:
The formation of iron hydroxide, Fe(OH)2, from Fe2+ and OH- is not considered an oxidation-reduction (redox) reaction because there is no transfer of electrons between the iron and the hydroxide ions. In an oxidation-reduction reaction, one species loses electrons (oxidation) while another species gains electrons (reduction). The formation of Fe(OH)2 is simply a combination of Fe2+ with OH- to form a precipitate, with no change in the oxidation state of iron from +2 to any other value.
Oxidation states are an essential aspect of redox reactions; in the reaction provided, Fe2+ remains in the same oxidation state throughout the process of combining with hydroxide ions. This is different from reactions where Fe2+ is oxidized to Fe3+, such as in the hydration process of iron(III) oxide to form rust, indicating a true redox reaction where iron's oxidation state changes.