Fe3O4 - Iron (II, III) oxide

What is Iron (II, III) oxide?

Fe3O4 occurs as a mineral with a chemical name Iron (II, III) oxide. It is also known as Magnetite or Magnetic oxide. It is stone iron-like, brownish to grey or black in colour. It is not transparent and has a characteristic greasy or metallic lustre.

Table of Contents

Production of Iron (II, III) oxide:

Schikorr reaction – This reaction is to convert iron(II) hydroxide (Fe(OH)2) into iron(II, III) oxide (Fe3O4). Under anaerobic conditions, ferrous hydroxide (Fe(OH)2) undergoes oxidation with water to form magnetite and molecular hydrogen. This process is explained by the Schikorr reaction.

3Fe(OH)2 → Fe3O4 + H2 +2H2O

Ferrous hydroxide Magnetite Hydrogen water

Properties of Magnetite (Fe3O4)

Fe3O4 Iron (II, III) oxide
Molecular Weight/ Molar Mass 231.533 g/mol
Density 5 g/cm³
Boiling Point 2,623°C
Melting Point 1,597°C

Iron ii iii Oxide Structure Fe3o4

Iron (II, III) oxide structure – Fe3O4

The above image describes the structure of the Iron (II, III) oxide. Fe3O4 is the chemical formula of Iron (II, III) oxide which has four oxygen atoms, and three iron atoms. The bond formation between iron and oxygen depends on the difference in electronegativity between them. Iron (Fe) is metal and oxygen(O2) is non-metal. The bond between them is called an Ionic bond.

Chemical reaction:

Steel production process – Reducing magnetite ore by carbon monoxide in a blast furnace gives the following reaction:

Fe3O4 + 4CO → 3Fe + 4CO2

Production of brown pigment – When magnetite undergoes controlled oxidation it produces quality γ-Fe2O3 and gives the following reaction:

2Fe3O4    +    ½ O2   →  3 𝛾-Fe2O3

(Magnetite)              (Maghemite)

Production of red pigment – When magnetite undergoes vigorous calcining it produces quality α-Fe2O3 and gives the following reaction:

2Fe3O4    +    ½ O2   →  3 α-Fe2O3

(Magnetite)                   (Hematite)

Uses of Magnetite (Fe3O4)

  • Iron (II, III) oxide is used as a black pigment also known as Mars Black.
  • It is used in the Haber process as a catalyst.
  • It is used in the water-gas shift reaction.
  • Its nanoparticles are used in MRI scanning as contrasts against it.
  • It protects the steel from rusting.
  • It is an ingredient in thermite which is used for cutting steel.

Learn more about the chemical properties and importance of Fe3O4 from the expert faculties at BYJU’S.

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