Copper Patina Formation (Verdigris)
2Cu + O2 + H2O + CO2 → Cu2(OH)2CO3
Overview
Copper slowly oxidizes in moist air containing CO₂ to form basic copper carbonate, the green patina known as verdigris. Copper is oxidized from Cu⁰ to Cu²⁺. Unlike iron rust, the copper patina forms a protective layer that prevents further corrosion, which is why copper roofs last centuries.
Participants
| Role | Substance | Coefficient | State |
|---|---|---|---|
| Reactant | Oxygen O | 1 | (g) |
| Reactant | Water H₂O | 1 | (l) |
| Reactant | Carbon Dioxide CO₂ | 1 | (g) |
| Reactant | Copper Cu | 2 | (s) |
Everyday Example
The Statue of Liberty's green color is copper patina formed over decades of exposure to New York's atmosphere.
Industrial Importance
Copper patination is deliberately accelerated in architecture for aesthetic purposes. Understanding copper corrosion is essential for building material selection.
Properties
- Type
- Redox
- Reversible
- No
- Energy
- Exothermic
- ΔH
- -720.0 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 Reduction of Silver Ion
Dichromate Oxidation of Ethanol
Frequently Asked Questions
What is the equation for Copper Patina Formation (Verdigris)?
The balanced equation is: 2Cu + O₂ + H₂O + CO₂ → Cu₂(OH)₂CO₃.
What type of reaction is Copper Patina Formation (Verdigris)?
Copper Patina Formation (Verdigris) is a redox reaction.
Is Copper Patina Formation (Verdigris) exothermic or endothermic?
Copper Patina Formation (Verdigris) is exothermic (releases energy). The enthalpy change (ΔH) is -720.0 kJ/mol.