Iron(II,III) oxide

Iron(II,III) oxide, also known as ferrous ferric oxide, magnetite, black iron oxide, is an iron oxide with the chemical formula Fe₃O₄.

Properties

Chemical

Magnitite can be calcinated in air to yield iron(III) oxide:

2Fe₃O₄ + ½ O₂ → 3 Fe₂O₃

Physical

Iron(II,III) oxide is a black compound, insoluble in water. It is ferrimagnetic and an electrical conductor.

Availability

Black iron oxide is available as pigment in pottery shops and can be cheaply purchased.

Preparation

There are several ways to prepare magnetite. One method involves the reduction of nitrobenzene with iron and water, in the presence of iron(II) chloride, process that reduces the nitrobenzene to aniline. It can also be done by precipitating iron(II) salts as hydroxides, then carefully oxidizing the resulting iron(II) hydroxide at controlled pH.

Black iron oxide can also be prepared by oxidizing iron(II) hydroxide with water, in an oxygen-free medium.

3 Fe(OH)₂ → Fe₃O₄ + H₂ + 2 H₂O

This process is known as Schikorr reaction.

Projects

• Thermite

Handling

Safety

Black iron oxide is not particularly toxic, unless large amounts are consumed.

Storage

It should be stored in closed containers, away from acidic vapors.

Disposal

As iron(II,III) oxide occurs naturally, it is not harmful to the environment and can be useful as an iron supplement for soil.