Beginner Topic 585 of 1102 Acids, Bases & Electrochemistry
Corrosion
Gradual destruction of metals by electrochemical reaction with the environment.
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In-depth explanation of Corrosion
Corrosion is the electrochemical deterioration of metals caused by their reaction with the environment, most commonly oxygen and water. The metal surface acts as a mosaic of tiny anodic and cathodic regions, with a thin moisture film serving as the electrolyte that completes the circuit. Oxidation occurs at the anodic sites, releasing metal ions, while reduction of oxygen or hydrogen ions occurs at cathodic sites. Corrosion costs many billions of dollars each year in damaged structures, vehicles and pipelines. Understanding the electrochemistry allows engineers to design protection strategies.
Going deeper: Corrosion
Key ideas: Corrosion is the electrochemical oxidation of a metal by its environment. It needs an anode, a cathode, an electrolyte and metallic contact. Anodic: M giving Mn+ + ne-. Cathodic: O2 + 2H2O + 4e- giving 4OH-, or 2H+ + 2e- giving H2 in acid. Types: uniform, galvanic, pitting, crevice, stress.
Common mistakes and connections: Mistake: thinking corrosion needs a separate piece of metal as the cathode; one piece with different regions suffices. Rate depends on moisture, salt (raises conductivity), pH and oxygen. Passivation protects Al, Cr and stainless steel. Concepts link to galvanic cell, Nernst equation and protective methods.
Visualization of Corrosion
Corrosion is a tiny galvanic cell: iron oxidizes at an anodic site while oxygen is reduced at a cathodic site, with a water film as the electrolyte. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Iron rusting, silver tarnishing and copper turning green are all examples of corrosion.
Frequently asked questions about Corrosion
What is Corrosion?
Gradual destruction of metals by electrochemical reaction with the environment.
Is Corrosion a beginner, intermediate or advanced topic?
Corrosion is a beginner topic in Acids, Bases & Electrochemistry. It needs no earlier chemistry lessons and is a good starting point.
What should I learn before Corrosion?
Study these earlier topics in Acids, Bases & Electrochemistry first: Nickel-Metal Hydride Battery, Fuel Cells, Solid-State Batteries.
What comes after Corrosion?
The next topics in Acids, Bases & Electrochemistry are Rusting of Iron and Prevention of Corrosion.
Can I practise Corrosion with quizzes?
Yes. The interactive lesson includes a self-check question on Corrosion, and the Acids, Bases & Electrochemistry quiz draws on every topic in this area.
Where Corrosion fits in Acids, Bases & Electrochemistry
Corrosion is topic 75 of 105 in Acids, Bases & Electrochemistry.