Barium

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Barium
Chemical formula Ba
Atomic Number 56 
OTP appearance silver-grey solid 
Molar Mass(g/mol) 137.3 
Melting Point(°C) 727 
Boiling Point(°C) 1825 
Density(g/cc) 3.51
NFPA 704
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One of the few period-6 elements we deal with, relatively difficult to isolate, and producing a variety of very toxic soluble salts, barium is useful in oxygen production and electronic components.

Uses

Justification Questioned

Other

  • Brinn process for oxygen Production
  • Barium-Aluminum alloy (Ba•2Al) is an excellent "getter" for vacuum tubes.
  • -sulfide produces hydrogen sulfide gas from water
  • -sulfide has native phosphorescence
  • -hydroxide is a strong alkali and produces endothermic reactions with ammonium salts

Natural Occurrences

  • Elemental barium does not occur naturally
  • -sulfate occurs natively as the mineral barite
  • -carbonate occurs natively as the mineral witherite

Hazards

  • soluble salts of barium are very toxic

Production

  • Produced by electrolysis of molten -chloride using a mercury cathode, producing a barium-mercury amalgam, which is heated to evaporate the mercury, leaving barium.
    BaCl2(l)
    {Hg
    962°C}
    Ba + Cl2(g)
  • Produced by aluminothermic Reduction (or Silicothermic) of -oxide
    4 BaO + 2 Al 3 Ba + BaAl2O4
Sir H Davy tried to electrolyse baryta but was unsuccessful. Later attempts were made by him using barium chloride in the presence of mercury. In this way he obtained an amalgam from which on distilling off the mercury the barium was obtained as a silver white residue. R Bunsen in 1854 electrolysed a thick paste of barium chloride and dilute hydrochloric acid in the presence of mercury at 100 C obtaining a barium amalgam from which the mercury was separated by a process of distillation. AN Guntz Comptus rendus 1001 133 p 872 electrolyses a saturated solution of barium chloride using a mercury cathode and obtains a 3% barium amalgam. This amalgam is transferred to an iron boat in a wide porcelain tube and the tube slowly heated electrically a good yield of pure barium being obtained at about 1000 C. The metal when freshly cut possesses a silver white lustre is a little harder than lead and is extremely easily oxidized on exposure it is soluble in liquid ammonia and readily attacks both water and alcohol.[1]

See Also

References

  1.  (1910) "Barium"
    Encyclopedia Britannica 11(3) University Press, Cambridge, UK