Question

Describe the chemical reactions that occur during the rusting of iron.

Answer 1

The rusting of iron is an electrochemical process that occurs in the presence of water and oxygen, resulting in the formation of hydrated iron(III) oxide, commonly known as rust. It begins with the oxidation of iron (Fe) at the anodic site, where iron atoms lose electrons to form iron(II) ions (Fe²⁺). Simultaneously, at the cathodic site, oxygen from the air dissolves in water and reacts with the released electrons to produce hydroxide ions (OH⁻). These ions combine with Fe²⁺ to form iron(II) hydroxide (Fe(OH)₂), which is unstable and further reacts with oxygen and water to produce iron(III) hydroxide (Fe(OH)₃). Over time, iron(III) hydroxide dehydrates to form hydrated iron(III) oxide (Fe₂O₃·xH₂O), the reddish-brown substance we recognize as rust. The process is accelerated by electrolytes, such as salt, or acidic conditions, which enhance conductivity and reactivity. Rusting weakens the metal, highlighting the importance of protective measures like coatings or galvanization to prevent corrosion.

 

Answer 2

Rusting of iron is a gradual chemical process that occurs when iron reacts with oxygen and water in the environment, resulting in the formation of iron oxide. The process begins with the oxidation of iron atoms when they lose electrons and form iron (II) ions. These iron (II) ions then react with water and oxygen, leading to the formation of iron (III) hydroxide. Over time, iron (III) hydroxide undergoes dehydration and further oxidation, ultimately turning into iron oxide-hydroxide, commonly known as rust. This process is an example of electrochemical corrosion, where iron acts as an anode, losing electrons, while oxygen and water act as cathodes, gaining electrons. As a result, rust weakens and deteriorates the iron over time.