Boron

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Boron
Chemical formula {{#Chem:B}}
Atomic Number
OTP appearance solid 
Molar Mass(g/mol) 10.81 
Density(g/cc) 2.33 to 2.53 
Melting Point(°C) 2076 
Boiling Point(°C) 3927
NFPA 704
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: {{#Chem: Na2B4O7(H2O)10 + 2 HCl = 5 H2O + 2 NaCl + 4 H3BO3 }}
    Kernite: {{#Chem: Na2B4O6(OH)2(H2O)3 + 2 HCl+ H2O = 2 NaCl + 4 H3BO3}}
    Colemanite: {{#Chem: CaB3O4(OH)3(H2O) + H2SO4 + H2O = CaSO4 + 3 H3BO3}}
    Howlite: {{#Chem: Ca2B5SiO9(OH)5 + 2 H2SO4 + 3 H2O = SiO2 + 2 CaSO4 + 5 H3BO3}}
  2. Produce boric oxide via thermal decomposition of boric acid
    {{#Chem: 2H3BO3 { = 300°C } B2O3 + 3H2O}}
  3. Produce elemental boron via magnesiothermic reduction of boric oxide
    {{#Chem: B2O3 + 3Mg = 2B + 3MgO}}

Purification

Testing

Storage

Disposal

See Also

References