Iron Corrosion (Rusting)

4Fe + 3O2 + 6H2O → 4Fe(OH)3

Overview

Iron corrosion is an electrochemical process where iron is oxidized to Fe²⁺/Fe³⁺ at anodic sites while oxygen is reduced at cathodic sites. The process requires both water and oxygen. The initial Fe(OH)₂ product is further oxidized to Fe(OH)₃, which dehydrates to form rust (Fe₂O₃·nH₂O).

Participants

Role Substance Coefficient State
Reactant Oxygen O 3 (g)
Reactant Iron Fe 4 (s)
Reactant Water H₂O 6 (l)

Everyday Example

A car's body rusting over time, iron nails turning orange-brown, and bridge structures corroding all involve this electrochemical process.

Industrial Importance

Corrosion costs the global economy over $2.5 trillion annually. Understanding and preventing iron corrosion is critical for infrastructure, transportation, and manufacturing.

Properties

Type
Redox
Reversible
No
Energy
Exothermic
ΔH
-1648.0 kJ/mol

Related Reactions

Aqua Regia Dissolving Gold Bleaching with Sodium Hypochlorite Cerium(IV) Reduction by Iron(II) Chlorine Oxidation of Bromide Chromate-Dichromate Equilibrium Contact Process SO₂ Oxidation Copper Displaced by Iron Copper Oxidation by Nitric Acid Copper Patina Formation (Verdigris) Copper Reduction of Silver Ion

Frequently Asked Questions

What is the equation for Iron Corrosion (Rusting)?
The balanced equation is: 4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃.
What type of reaction is Iron Corrosion (Rusting)?
Iron Corrosion (Rusting) is a redox reaction.
Is Iron Corrosion (Rusting) exothermic or endothermic?
Iron Corrosion (Rusting) is exothermic (releases energy). The enthalpy change (ΔH) is -1648.0 kJ/mol.