Iron Oxide

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Created by: Team Chemistry -, Last Updated: May 23, 2024

Iron Oxide

Iron(III) oxide is also known as ferric oxide. It is a chemical compound made of iron and oxygen with the formula Feβ‚‚O₃. In chemistry, we often see it as a reddish-brown powder commonly found in rust and used as a pigment. It forms when iron reacts with oxygen in the air, creating a coating that protects the iron underneath from further corrosion. Iron(III) oxide is significant in both chemistry and industry, playing a crucial role in the production of iron and steel, and it’s also used in magnetic materials and polishing compounds.

What is Iron(III) Oxide?

Iron(III) oxide is also known as ferric oxide. It is a chemical compound with the formula Feβ‚‚O₃. It consists of iron and oxygen, where iron is in the +3 oxidation state. This compound commonly appears as a reddish-brown powder and is one of the main oxides of iron. Iron(III) oxide is used in various applications, including as a pigment in paints and coatings, and as a raw material in the production of iron and steel.

Chemical Names and Formulas

NameIron(III) Oxide
Alternate NamesDiiron Trioxide, Ferric Oxide, Haematite, Hematite, Iron Sesquioxide, Oxo-(Oxoferriooxy)iron, Red Iron Oxide, Specularite

Structure of Iron(III) Oxide


The structure of Iron(III) oxide, also known as ferric oxide (Feβ‚‚O₃), consists of iron and oxygen atoms arranged in a repeating pattern. In this structure, each iron atom is surrounded by six oxygen atoms in an octahedral shape, and each oxygen atom is connected to two iron atoms. This creates a lattice structure where iron and oxygen atoms alternate, forming a stable and solid crystalline material. The arrangement allows Iron(III) oxide to have strong bonds, making it a durable compound commonly found in nature as the mineral hematite.

Preparation of Iron(III) Oxide

To prepare Iron(III) oxide, you can use a simple method involving the reaction between iron and oxygen. When you heat iron in the presence of oxygen, it reacts to form Iron(III) oxide. This process is straightforward and can be performed in a lab setting.

First, you take a piece of iron and heat it strongly in the presence of oxygen. The iron reacts with the oxygen to produce Iron(III) oxide, which appears as a reddish-brown powder. The chemical equation for this reaction is:

4𝐹𝑒 + 3𝑂₂ β†’ 2Feβ‚‚O₃

Alternatively, you can prepare Iron(III) oxide by decomposing iron(III) hydroxide. When you heat iron(III) hydroxide, it breaks down to form Iron(III) oxide and water. The chemical equation for this reaction is:

2𝐹𝑒(𝑂𝐻)₃ β†’ Feβ‚‚O₃ + 3𝐻₂𝑂

Both methods result in the formation of Iron(III) oxide, commonly used in various applications, including pigments and the steel industry.

Physical Properties of Iron(III) Oxide

Density5.24 g/cmΒ³
Melting Point1565Β°C
Boiling PointDecomposes before boiling
Solubility in WaterInsoluble
Magnetic PropertiesWeakly magnetic (paramagnetic)

Chemical Properties of Iron(III) Oxide

Reaction with Acids

  • Iron(III) oxide reacts with acids, such as hydrochloric acid, to form iron(III) chloride and water. This reaction demonstrates its basic nature.
  • Equation: Feβ‚‚O₃ + 6𝐻𝐢𝑙 β†’ 2𝐹𝑒𝐢𝑙₃ + 3𝐻₂𝑂

Reaction with Bases

  • Iron(III) oxide reacts with strong bases, like sodium hydroxide, to form sodium ferrate and water, showcasing its amphoteric nature.
  • Equation: Feβ‚‚O₃ + 2π‘π‘Žπ‘‚π» + 3𝐻₂𝑂 β†’ 2π‘π‘ŽπΉπ‘’π‘‚β‚‚ + 3𝐻₂𝑂

Reaction with Carbon

  • When heated with carbon, iron(III) oxide reduces to iron and carbon dioxide. This reaction is used in the extraction of iron from its ores.
  • Equation: Feβ‚‚O₃ + 3𝐢 β†’ 2𝐹𝑒 + 3𝐢𝑂₂

Reaction with Hydrogen

  • Iron(III) oxide reacts with hydrogen gas upon heating, forming iron and water. This reaction is another method for producing iron.
  • Equation: Feβ‚‚O₃ + 3𝐻₂ β†’ 2𝐹𝑒 + 3𝐻₂𝑂

Iron(III) Oxide Chemical Compound Information

Chemical Identifiers

CAS Registry Number1309-37-1
PubChem Compound ID14833
SMILES Identifier[Fe+3].[Fe+3].[O-2].[O-2].[O-2]
EU Number215-275-4
Gmelin Number-81
RTECS NumberNO7400000
MDL NumberMFCD00011008

Uses of Iron(III) Oxide


Pigment in Paints

Iron(III) oxide serves as a pigment in paints, providing a reddish-brown color. It is widely used in art and industrial applications.

Polishing Agent

Manufacturers use Iron(III) oxide as a polishing agent, especially in the final polishing of metallic jewelry and lenses, due to its abrasive properties.

Steel Manufacturing

In steel manufacturing, Iron(III) oxide is a crucial component. It is reduced to produce iron, which is then converted into steel.

Magnetic Storage Media

Iron(III) oxide is used in magnetic storage media, such as tapes and disks, due to its magnetic properties, which help store data effectively.


Industries use Iron(III) oxide as a catalyst in various chemical reactions, such as the production of ammonia in the Haber process.

Ceramic Glazes

Iron(III) oxide is used in ceramic glazes, providing color and helping to create different finishes on pottery and tiles.

Side Effects of Iron(III) Oxide

  • Skin Irritation: Can cause irritation upon contact with skin.
  • Eye Irritation: Dust particles may irritate the eyes.
  • Respiratory Issues: Inhaling dust can lead to respiratory problems.
  • Allergic Reactions: Some people may experience allergic reactions.
  • Gastrointestinal Distress: Ingesting large amounts can cause stomach pain and nausea.
  • Environmental Impact: Can contribute to air and water pollution if not managed properly.

Why is iron III oxide Feβ‚‚O₃?

Iron(III) oxide has the formula Feβ‚‚O₃ because it consists of iron in the +3 oxidation state combined with oxygen atoms.

What is iron oxide also known as?

Iron oxide is also known as ferric oxide or hematite in its natural mineral form.

Is rust really iron III oxide?

Yes, rust primarily consists of iron(III) oxide (Feβ‚‚O₃), formed when iron reacts with oxygen and moisture.

How bad is iron oxide?

Iron oxide can cause skin, eye, and respiratory irritation, but it is generally considered low in toxicity with proper handling.

How do you make iron oxide rust?

To make iron oxide rust, expose iron to oxygen and moisture, allowing it to undergo oxidation.

What is the difference between iron oxide and ferric oxide?

Iron oxide refers to compounds of iron and oxygen, while ferric oxide specifically denotes iron(III) oxide (Feβ‚‚O₃).

Does vinegar dissolve iron oxide?

Yes, vinegar, containing acetic acid, can dissolve iron oxide by reacting with it and breaking it down.

What type of bond is iron(III) oxide?

Iron(III) oxide has ionic bonds between iron cations (Fe³⁺) and oxygen anions (O²⁻).

Is Iron(III) oxide soluble in water?

No, Iron(III) oxide is insoluble in water due to its strong ionic bonds and crystalline structure.

Is Feβ‚‚O₃ polar or nonpolar?

Feβ‚‚O₃ is considered polar due to the difference in electronegativity between iron and oxygen, creating an uneven charge distribution.

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