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Rhodium

Rhodium was identified in 1804 by Wollaston in a platinum ore from South America.

The name is derived from the Greek ροδον (pink) on account of the pinkish-red colour of rhodium salts.

Properties

  • A silvery white, shiny metal.
  • Does not tarnish in air.
  • Exhibits outstanding resistance to corrosion.
  • Endowed with high light-reflecting power and is very hard. Mechanically, it is one of the strongest metals.
  • Brought to red-hot temperature in air, it converts slowly to the sesquioxide Rh2O3.

Applications

  • An important component of car catalysts in that it contributes to the reduction of the nitrogen oxides NOx.
  • Used in the manufacture of thermocouples, laboratory crucibles and bushings for drawing glass fibres, as well as in the production of high-grade glass (for computer screens).
  • Electrodeposition of rhodium gives extremely hard coatings used in the manufacture of mirrors for optical instruments.
  • In the form of very fine films, rhodium protects silverware against tarnishing.
  • Rhodium used in jewelry, for example in the production of white gold

Recycling

Rhodium is mainly recycled from spent automotive catalysts.