Corrosion reactions

Spontaneous redox reactions in which a metal is attacked by some substance in its environment and converted into an unwanted compound.
Oxidation
For nearly all metals, oxidation is thermodynamically favorable in air at room temperature.
  • Oxidation can form an insulating protective oxide layer; however, that prevents further reaction of the underlying metal.
  • Oxidation of the metal protects it from corrosion
  • Ex: stainless steel forms a protective impervious oxide coat to protect the underlying metal from further corrosion.
  • Corrosion of Iron (Rusting)
  • Requires both Oxygen and Water.
  • Involves oxidation and reduction
  • Cathodic Protection
    Used to prevent corrosion of metal by having a sacrificial anode be oxidized instead.
  • For example, to prevent iron rusting, a coat of Zinc can be applied. Even if the coating is chipped and the Fe is exposed, corrosion occurs to the Zn as the Zn has a lower standard reduction potential.
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