Boron

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Boron
Chemical formula B
Atomic Number
OTP appearance solid 
Molar Mass(g/mol) 10.81 
Melting Point(°C) 2076 
Boiling Point(°C) 3927 
Density(g/cc) 2.33 to 2.53
NFPA 704
NFPA704.png
3
2
0
 

Elemental Boron is rarely required. Normally it is used in a reduced state.

Uses

Justification Questioned

Primary

Secondary

  • Detergents (as sodium tetraborate)
  • Fire retardants for wood and cloth
  • Semiconductor dopant
  • High-hardness metal alloys

Natural Occurrence

  • Elemental boron does not occur naturally.
  • sodium boron hydroxide occurrs in the minerals kernite and borax
  • calcium boron hydroxide occurrs as the mineral colemanite

Hazards

Production

Extraction

  1. Produce boric acid by combining the boron ore with a mineral acid such as hydrochloric, sulfuric or phosphoric
    Borax: Na2B4O7(H2O)10 + 2 HCl 5 H2O + 2 NaCl + 4 H3BO3
    Kernite: Na2B4O6(OH)2(H2O)3 + 2 HCl + H2O 2 NaCl + 4 H3BO3
    Colemanite: CaB3O4(OH)3(H2O) + H2SO4 + H2O CaSO4 + 3 H3BO3
    Howlite: Ca2B5SiO9(OH)5 + 2 H2SO4 + 3 H2O SiO2 + 2 CaSO4 + 5 H3BO3
  2. Produce boric oxide via thermal decomposition of boric acid
    2 H3BO3
    {
    300°C}
    B2O3 + 3 H2O
  3. Produce elemental boron via magnesiothermic reduction of boric oxide
    B2O3 + 3 Mg 2 B + 3 MgO

Purification

Testing

Storage

Disposal

See Also

References