What is the common name for iron oxide?

A common name for iron oxide is iron (III) oxide or rust. The chemical formula for this substance is Fe₂O₃. However, there are other compounds that consist of oxygen and iron, such as magnetite, which has the formula Fe₃O₄.

Iron (III) oxide is the reaction between the metal iron and excess oxygen found in air. The balanced chemical equation for this reaction is 4Fe(s) + 3O₂(g) produces 2Fe₂O₃(s), where "s" stands for solid and "g" is gas. Hematite, which is a mineral found in nature, also has this same formula. Hematite is reddish in appearance.

Magnetite is another mineral formed in nature and is black in color. The formation of Fe₃O₄ occurs when iron is heated in the presence of small amounts of oxygen.