Corrosion is a naturally occurring electrochemical process that degrades metals. It changes the appearance and properties of familiar materials, from iron that rusts to copper that develops the blue-green patina seen on the Statue of Liberty.
Corrosion is the degradation of a metal through a naturally occurring electrochemical process. In these reactions, metal atoms are generally oxidized—they lose electrons. A reduction reaction occurs alongside oxidation, consuming those electrons.
All flashcards
What is corrosion?
The degradation of a metal through a naturally occurring electrochemical process, generally involving oxidation of the metal.
How does copper develop a blue-green patina?
Copper first forms oxides by reacting with oxygen; these oxides then react with atmospheric substances such as carbon dioxide, water, and sulfur-containing compounds.
How is rust represented, and why can its composition vary?
Rust is hydrated iron(III) oxide, represented as Fe2O3⋅xH2O; the amount of water varies.
What is galvanization?
Protecting iron or steel by coating it with a more readily oxidized metal, usually zinc.
What is a sacrificial anode?
A more active metal that oxidizes preferentially to protect another metal in cathodic protection.
Quiz questions
Which atmospheric substances can react with copper(II) oxide to form blue-green patina compounds?Answer: Carbon dioxide, water, and sulfur-containing substances.
What occurs at the anode when iron corrodes?Answer: Iron atoms form iron(II) ions and release electrons.
For iron corrosion under acidic standard conditions, what standard cell potential is given for the overall reaction?Answer: +1.67 V.
In cathodic protection, what role does the protected iron structure serve?Answer: It serves as the cathode in the electrochemical cell.
When a zinc coating on iron is locally damaged, how can zinc help protect the exposed iron?Answer: Zinc oxidizes preferentially and supplies electrons that help protect the iron.
Based on Chemistry 2e by Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson, PhD (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.