The chemistry of corrosion of iron is essentially an electrochemical phenomenon. Explain the reactions occurring during the corrosion of iron in the atmosphere.

The corrosion of iron in the atmosphere primarily involves the following electrochemical reactions:

1. Formation of Iron Oxide (Rusting): When iron is exposed to atmospheric oxygen and moisture, it undergoes oxidation to form iron oxide, commonly known as rust. The overall reaction is:

   4Fe+3O2+6H2O→4Fe(OH)34Fe+3O2+6H2O→4Fe(OH)3

   This reaction occurs in the presence of water and oxygen. Iron atoms lose electrons to oxygen molecules, forming iron ions (Fe²⁺) and hydroxide ions (OH⁻). These ions then react with water molecules to form rust (Fe(OH)₃).

2. Electron Transfer (Oxidation Reaction): The oxidation of iron can be represented as:

   Fe→Fe2++2e−Fe→Fe2++2e−

   Iron atoms lose electrons to form ferrous ions (Fe²⁺). This process is known as oxidation. These electrons released during oxidation are involved in the reduction half-reaction.

3. Reduction Reaction (Oxygen Reduction): Atmospheric oxygen reacts with water and electrons to form hydroxide ions. This reaction is represented as:

   O2+2H2O+4e−→4OH−O2+2H2O+4e−→4OH−

   Oxygen molecules gain electrons and react with water molecules to form hydroxide ions (OH⁻). This process is called reduction.

4. Overall Reaction: Combining the oxidation and reduction half-reactions, we get the overall reaction for the corrosion of iron in the atmosphere:

   4Fe+3O2+6H2O→4Fe(OH)34Fe+3O2+6H2O→4Fe(OH)3

   This reaction shows the formation of rust (iron hydroxide) from iron, oxygen, and water.

In summary, the corrosion of iron in the atmosphere is an electrochemical process involving the oxidation of iron and reduction of oxygen. Moisture and oxygen from the atmosphere facilitate the formation of rust, leading to the degradation of iron structures over time.