Ruthenium (44)

Ruthenium is a hard, white metal. It does not tarnish at room temperatures, but oxidizes in air at about 800°C. The metal is not attacked by hot or cold acids or aqua regia, but when potassium chlorate is added to the solution, it oxidizes explosively.

Ruthenium, rhodium, palladium, osmium, iridium, and platinum together make up a group of elements referred to as the platinum group metals (PGM).

•Name: Ruthenium
•Symbol: Ru
•Atomic number: 44
•Atomic weight: 101.07
•Standard state: solid at 298 K
•CAS Registry ID: 7440-18-8
•Group in periodic table: 8
•Group name: Precious metal or Platinum group metal
•Period in periodic table: 5
•Block in periodic table: d-block
•Color: silvery white metallic
•Classification: Metallic

Historical information

Ruthenium was discovered by Karl Karlovich Klaus at 1844 in Russia. Origin of name is from the Latin word "Ruthenia" meaning "Russia". Ruthenium was isolated in 1844 by Karl Karlovich Klaus, who obtained ruthenium from the part of crude platinum that is insoluble in aqua regia (very cool cleaning solution made up of two acids - nitric and hydrochloric). It is possible that a Polish chemist Jedrzej Sniadecki had in fact isolated ruthenium from some platinum ores rather earlier than this in 1807 but his work was not ratified, apparently as he withdrew his claims. He called it vestium.

Physical properties

•Melting point: 2607 [or 2334 °C (4233 °F)] K
•Boiling point: 4423 [or 4150 °C (7502 °F)] K
•Density of solid: 12370 kg m-3

Orbital properties

•Ground state electron configuration: [Kr].4d75s1
•Shell structure: 2.8.18.15.1
•Term symbol: 5F5

Isolation

It would not normally be necessary to make a sample of ruthenium in the laboratory as the metal is available, at a price, commercially. The industrial extraction of ruthenium 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 particular industrial operation while in other cases it is a byproduct. The extraction is complex because of the other metals present and only worthwhile since ruthenium 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 bisulfate (NaHSO4) and the resulting mixture extracted with water to give a solution containing rhodium sulphate, Rh2(SO4)3. The insoluble residue contains the ruthenium. The residue is melted with Na2O2 and extracted into water to extract the ruthenium and osmium salts (including [RuO4]2- and [OsO4(OH)2]2-). The residue contains iridium oxide, IrO2. Reaction of the salt with chlorine gas gives the volatile oxides RuO4 and OsO4. The ruthenium oxide is dissolved by treatment with hydrochloric acid to form H3RuCl6, and the ruthenium precipitated out as pure (NH4)3RuCl6 by treatment with NH4Cl. Evaporation to dryness and burning under hydrogen gas gives pure ruthenium.