Corrosion

When exposed to moist air for a long period of time, metals become corroded. This is known as CorrosionFor Example, Silver reacts with moist air and becomes black in colour due to silver sulphide coating.

                                   Iron + oxygen → Iron (III) oxide

                                               Fe + O2 → Fe2O3

Prevention of Corrosion

  • Rusting of iron can be prevented by oiling, galvanising, painting, greasing etc.
  • To protect steel and iron from rusting, a thin layer of zinc is coated on them, this is known as Galvanization.