Corrosion – Class 12 | Chapter – 3 | Chemistry Short Notes Series PDF for NEET & JEE

Corrosion: Corrosion is the deterioration of a material or metal due to a chemical or electrochemical reaction with its environment. Corrosion can occur in many forms, including rusting, tarnishing, and pitting, and it can have a significant impact on the lifespan and performance of materials and structures.

Forms of Corrosion

The most common form of corrosion is the oxidation of metals, such as iron and steel, which react with oxygen in the air to form iron oxide (rust). Other forms of corrosion include:

  • Galvanic corrosion: This occurs when two dissimilar metals are in contact with each other in the presence of an electrolyte, such as saltwater. The more active metal corrodes more quickly, while the less active metal remains intact.
  • Crevice corrosion: This occurs in small crevices or gaps between metals, where stagnant water or other corrosive substances can accumulate and cause localized corrosion.
  • Corrosion cracking: This occurs when a metal is subjected to tensile stresses and a corrosive environment, which can lead to cracking and failure of the material.
  • Environmental corrosion: This includes corrosion caused by exposure to chemicals, pollutants, and other environmental factors, such as acid rain and salt spray.

Methods of preventing Corrosion

Corrosion can have serious consequences, such as structural failure, loss of function, and safety hazards. Preventing or controlling corrosion is essential in many industries, including construction, transportation, and manufacturing. Some methods of preventing corrosion include:

  • Protective coatings: Applying a coating of paint, epoxy, or other materials can protect a metal surface from exposure to corrosive substances.
  • Cathodic protection: This involves using a sacrificial metal, such as zinc, to protect the more valuable metal from corrosion.
  • Alloying: Adding other metals to a base metal can improve its corrosion resistance.
  • Design modifications: Making design changes to eliminate crevices or other areas where corrosion can occur can help prevent corrosion.
  • Corrosion inhibitors: These are chemicals that can be added to a system to prevent or reduce corrosion.

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By Team Learning Mantras