Corrosion and Rancidity

Corrosion and Rancidity (Daily Life Importance)

Corrosion

When metal reacts with air + moisture (mainly oxygen + water vapor)
➡️ Forms a layer of oxide, which damages the metal.

Example:
Rusting of iron
4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃ → Fe₂O₃·xH₂O (rust)

Prevention:

• Painting

• Galvanization (coating with zinc)

• Oil/grease layer

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Rancidity

Fats and oils in food get oxidized when exposed to air.
➡️ They smell and taste bad.

Causes:

• Light

• Oxygen

• Heat

Prevention:

• Airtight packing

• Using antioxidants (like BHA/BHT)

• Refrigeration