Platinum

From NOWA-CL
Jump to navigation Jump to search
 
Platinum
Chemical formula Pt
Atomic Number 78 
OTP appearance silvery solid 
Molar Mass(g/mol) 195 
Melting Point(°C) 1769 
Boiling Point(°C) 4825 
Density(g/cc) 21.45 
Coefficient of Thermal Expansion(×10-6 °C-1) 8
NFPA 704
NFPA704.png
2
1
0
 

Along with gold, Platinum is classed as a noble metal because it is extremely unreactive. Platinum also has a very high melting point. This and its nonreactive nature make it an excellent catalyst and electrode. It is definitely not widely available.

Uses

Primary

Other

  • As an electrode
  • As a catalyst
  • As platinum black

Natural Sources

  • Elemental platinum does occur naturally
  • Elemental platinum occurs as an impurity in silver and gold
    • Platinum exists in virtually all placer gold, but in ppm quantities:
      • ... One dredging company, which recovered about 50,000 ounces of gold from 10,000,000 cubic yards of gravel, sold about 110 ounces of crude platinum metals; these contained 70 ounces of platinum (~1400ppm) and 6 or 8 (~140ppm) ounces each of iridium and osmium.[1]
  • Platinum appears as a minute impurity (3-6ppm, g/ton) in chalcopyrite and pentlandite.

Production

Extraction

From gold-platinum alloy

  1. Dissolve gold-platinum in aqua regia
  2. Slowly add enough iron (III) sulfate to precipitate all the gold
  3. Separate gold from solution and wash gold with hydrochloric acid
  4. Neutralize platinum solution, precipitating platinum.

See Also

  • gold, nickel, and copper, whose ores often contain a small percentage of platinum

References

  1. Gardner, E. D.; Johnson, C. H. (1934) "Placer Mining in the Western United States"
    United States Bureau of Mines Information Circular(6786)