**How is Rust Formed?**

Rust is a common form of corrosion that occurs on iron and iron alloys such as steel. It is a chemical reaction between iron, oxygen, and water, resulting in the formation of iron oxide, which is commonly known as rust. This process is known as oxidation, and it can be explained in detail as follows:

**1. Presence of Iron**
Rust forms when iron or iron alloys are exposed to the surrounding environment. Iron is a highly reactive metal and readily reacts with oxygen in the presence of water.

**2. Oxidation Reaction**
The process of rust formation involves an oxidation reaction. The iron atoms lose electrons, resulting in the formation of iron(II) ions (Fe2+). This reaction is facilitated by the presence of water, as it provides a medium for the movement of ions.

**3. Formation of Iron(II) Ions**
When iron reacts with oxygen, it forms iron(II) ions by losing two electrons according to the following reaction:
2Fe(s) + O2(g) + 4H2O(l) -> 2Fe2+(aq) + 4OH-(aq)

**4. Conversion to Iron(III) Ions**
The iron(II) ions formed in the previous step combine with oxygen from the air to form iron(III) ions (Fe3+). This conversion is facilitated by the presence of water and the reaction occurs as follows:
4Fe2+(aq) + O2(g) + 2H2O(l) -> 4Fe3+(aq) + 4OH-(aq)

**5. Formation of Rust**
The iron(III) ions produced in the previous step react with water and oxygen to form hydrated iron(III) oxide, commonly known as rust. This reaction can be represented as:
4Fe3+(aq) + 6H2O(l) + 3O2(g) -> 4Fe(OH)3(s)

**6. Characteristics of Rust**
Rust is a reddish-brown, flaky substance that adheres to the surface of iron or steel. It is chemically unstable and continues to react with oxygen and water, causing further corrosion if not treated or removed.

**Conclusion**
Rust formation is a result of the oxidation of iron in the presence of oxygen and water. This chemical reaction leads to the formation of iron oxide, commonly known as rust. Understanding the process of rust formation is crucial in preventing and managing corrosion, as it allows us to develop effective strategies for rust prevention and treatment.

When iron reacts with oxygen and moisture present in the atmosphere to form a reddish-brown ,flaky substance called rust. In this way rust is formed.