|Name: iridium||Group number: 9|
|Symbol: Ir||Group name: Precious metal or Platinum group metal|
|Atomic number: 77||Period number: 6|
|Atomic weight: 192.217 (3)||Block: d-block|
|CAS Registry ID: 7439-88-5||Voice: |
|Standard state: solid at 298 K||Colour: silvery white|
|Classification: Metallic||Availability: iridium is available in many forms inclu|
Nearing Zero cartoon included by kind permission of Nick Kim.
IsolationHere is a brief summary of the isolation of iridium.
It would not normally be necessary to make a sample of iridium in the laboratory as the metal is available, at a price, commercially. The industrial extraction of iridium is complex as the metal occurs in ores mixed with other metals such as rhodium, palladium, silver, platinum, and gold. Sometimes extraction of the precious metals such as iridium, rhodium, platinum and palladium is the main focus of a partiular industrial operation while in other cases it is a byproduct. The extraction is complex because of the other metals present and only worthwhile since iridium is useful as a specialist metal and is the basis of some catalysts in industry.
Preliminary treatment of the ore or base metal byproduct is required to remove silver, gold, palladium, and platinum. The residue is melted with sodium bisulphate (NaHSO4) and the resulting mixture extracted with water to give a solution containing rhodium sulphate, Rh2(SO4)3. The insoluble residue contains the iridium. The residue is melted with Na2O2 and extracted into water to remove ruthenium and osmium salts. The residue contains iridium oxide, IrO2. Dissolution of the oxide in regia (a mixture of hydrochloric acid, HCl, and nitric acid, HNO3) gives a solution containing pure (NH4)3IrCl6. Evaporation to dryness and burning under hydrogen gas gives pure iridium.