Chromium

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Chromium
Chemical formula {{#Chem:Cr}}
Atomic Number 24 
OTP appearance solid 
Density(g/cc) 7.2 
Melting Point(°C) 1907 
Boiling Point(°C) 2671 
Coefficient of Thermal Expansion(×10-6 °C-1) 4.9
NFPA 704
1
2
1
 

Uses

Primary

  • Stainless steel
  • High speed steel
  • Electroplating

Secondary

  • Tanning
  • Cleaning glassware via chromic acid
  • Combined with Nickel for heating elements

Natural Occurrence

  • Elemental chromium does not occur naturally
  • Iron chromium oxide ({{#Chem: FeCr2O4}}) occurrs as the mineral Chromite
  • Lead chromium oxide ({{#Chem: PbCrO4}}) occurrs as the mineral Crocoite

Hazards

Chromium is toxic and carcinogenic in its hexavalent state. Production of chromium metal often takes a path through (VI) to separate other materials, only to reduce it to (III) later. This makes chromium production via this path very dangerous.

Production

Extraction

See chromium processing for details on extracting both the pure metal and its various salts from naturally occurring chromite

Purification

Testing

Storage

Disposal

See Also

Referencexs