Anodizing of Aluminum

2Al + 3H2O → Al2O3 + 6H+ + 6e−

Overview

Anodizing grows a thick, porous aluminum oxide layer on aluminum surfaces by making the aluminum the anode in an acid electrolyte (typically 15–20% H₂SO₄). The oxide layer (5–25 μm for decorative, up to 150 μm for hard anodizing) provides corrosion resistance, wear resistance, and can absorb dyes for coloring.

Participants

Role Substance Coefficient State
Reactant Aluminum Al 2 (s)
Reactant Water H₂O 3 (l)
Product Aluminum Oxide Al₂O₃ 1 (s)

Everyday Example

Apple MacBooks, iPhones, and many premium electronics use anodized aluminum for the durable, colored finish.

Industrial Importance

Anodizing is used in aerospace, architecture, automotive, and consumer electronics. The market exceeds $4 billion annually.

Properties

Type
Electrochemical
Reversible
No
Energy
Endothermic
ΔH
871.0 kJ/mol

Related Reactions

Alkaline Battery Discharge Cathodic Protection (Zinc Sacrificial Anode) Chlor-Alkali Electrolysis Chrome Electroplating Copper Electroplating Daniell Cell (Zinc-Copper Galvanic Cell) Electrochemical CO₂ Reduction to CO Electrochemical Machining (ECM) Electrolysis of Molten NaCl (Downs Process) Electrolysis of Water

Frequently Asked Questions

What is the equation for Anodizing of Aluminum?
The balanced equation is: 2Al + 3H₂O → Al₂O₃ + 6H⁺ + 6e⁻.
What type of reaction is Anodizing of Aluminum?
Anodizing of Aluminum is a electrochemical reaction.
Is Anodizing of Aluminum exothermic or endothermic?
Anodizing of Aluminum is endothermic (absorbs energy). The enthalpy change (ΔH) is 871.0 kJ/mol.