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
• Properties of Magnetite (Fe3O4)
• Chemical reaction
• Uses of Magnetite (Fe3O4)

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)

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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