Chemical elements
  Iridium
    Isotopes
    Energy
    Production
    Application
    Physical Properties
    Chemical Properties
      Iridium Monochloride
      Iridium Dichloride
      Iridium Trichloride
      Potassium Chloriridite
      Sodium Chloriridite
      Ammonium Chloriridite
      Aquo Chloriridites
      Iridium Tetrachloride
      Potassium Chloriridate
      Sodium Chloriridate
      Ammonium Chloriridate
      Silver Chloriridate
      Thallium Chloriridate
      Iridium Tribromide
      Iridium Tetrabromide
      Potassium Bromiridate
      Sodium Bromiridate
      Ammonium Bromiridate
      Iridium Oxybromide
      Iridium Tri-iodide
      Potassium Iodiridite
      Iridium Tetra-iodide
      Potassium Iodiridate
      Iridium Monoxide
      Iridium Sesquioxide
      Iridium Dioxide
      Iridium Trioxide
      Iridium Monosulphide
      Iridium Sesquisulphide
      Iridium Disulphide
      Iridium Sesquisulphite
      Potassium Iridium Sulphite
      Iridium Sesquisulphate
      Potassium Iridium Alum
      Ammonium Iridium Alum
      Caesium Iridium Alum
      Rubidium Iridium Alum
      Iridium Disulphate
      Iridium Sesquiselenide
      Hydrogen Iridi-nitrite
      Potassium Iridi-nitrite
      Sodium Iridi-nitrite
      Ammonium Iridi-nitrite
      Hydrogen Iridicyanide
      Potassium Iridicyanide
      Barium Iridicyanide
    PDB 1c1k-4enb

Chemical Properties of Iridium






Iridium is not attacked by fluorine in the cold, but on warming to dull redness, vapours of the fluoride are evolved. Also, when employed as anode in the preparation of fluorine, it is rapidly attacked. Chlorine at red heat unites with iridium to form the trichloride; a mixture of chlorine and carbon monoxide at 240° C. has no action on the metal although platinum is attacked by it.

Finely divided iridium, when heated to redness in air, absorbs a certain amount of oxygen, forming an indefinite mixture of oxides. It is attacked by sulphur vapour at red heat, and under similar conditions phosphorus combines with it to form a fusible phosphide, which decomposes at white heat in a lime furnace, yielding the free metal.

Acids, even aqua regia, have no action on iridium, unless it is very finely divided, in which case it is very slowly attacked.

Fusion with a mixture of potassium hydroxide and nitrate results in the formation of iridates. Fused with potassium hydrogen sulphate it yields the sesquioxides. Alkalis alone have no action when fused with iridium.

Heated for some hours in a Bunsen burning with a smoky flame, an iridium crucible is unharmed, since the deposit of carbon can be entirely burnt away. Sulphur in the gas is likewise without effect. Prolonged ignition with copper renders the metal brittle, but the copper can be burnt off.

When strips of iridium are heated to high temperatures in carbon monoxide or in nitrogen, no loss in weight occurs. In carbon dioxide and in nitrogen containing oxygen appreciable losses in weight occur at 1500° C. upwards. This is attributed to the formation of oxide, which is volatile at these high temperatures.


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