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Barium carbonate



Barium carbonate
Other names witherite
Identifiers
CAS number 513-77-9
Properties
Molecular formula BaCO3
Molar mass 197.336 g/mol
Appearance white crystals
Density 4.2865 g/cm3, solid
Melting point

811 °C

Boiling point

1555 °C

Solubility in water .002 g/100 ml (20 °C)
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Barium carbonate (BaCO3), also known as witherite, is a chemical compound used in rat poison, bricks and cement.

Additional recommended knowledge

Witherite crystallizes in the orthorhombic system. The crystals are invariably twinned together in groups of three, giving rise to pseudo-hexagonal forms somewhat resembling bipyramidal crystals of quartz, the faces are usually rough and striated horizontally.

The mineral is named after William Withering, who in 1784 recognized it to be chemically distinct from barytes. It occurs in veins of lead ore at Hexham in Northumberland, Alston in Cumbria, Anglezarke, near Chorley in Lancashire and a few other localities. Witherite is readily altered to barium sulfate by the action of water containing calcium sulfate in solution and crystals are therefore frequently encrusted with barytes. It is the chief source of barium salts and is mined in considerable amounts in Northumberland. It is used for the preparation of rat poison, in the manufacture of glass and porcelain, and formerly for refining sugar. It is also used for controlling the chromate to sulfate ratio in chromium electroplating baths.[1]

Reactions

Barium carbonate reacts with many acids to soluble barium salts, for example barium chloride:

BaCO3(s) + 2 HCl(aq) → BaCl2(aq) + CO2(g) + H2O(l)

However the reaction with sulfuric acid is poor, because barium sulfate is highly insoluble.

References

  1. ^ Whitelaw, G.P. (2003-10-25). Standard Chrome Bath Control (English). finishing.com. Retrieved on 2006-11-29.
  • This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Barium_carbonate". A list of authors is available in Wikipedia.
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