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Barium carbonate
From Wikipedia, the free encyclopedia
| Barium carbonate | |
|---|---|
| Image:Barium carbonate.jpg | |
| General | |
| Other names | witherite |
| Molecular formula | BaCO3 |
| Molar mass | 197.336 g/mol |
| Appearance | white crystals |
| Crystal Structure | orthorhombic |
| CAS number | 513-77-9 |
| Properties | |
| Density and phase | 4.2865 g/cm3, solid |
| Solubility | insoluble in water soluble in acid |
| Melting point | 811 °C |
| Boiling point | 1555 °C |
| Refractive Index | 1.676 |
| Mohs hardness | 3.5 |
| Specific gravity | 4.3 |
| 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.
Wetherite 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 harytes. 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]
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.
- ^ Whitelaw, G.P. (2003-10-25). Standard Chrome Bath Control (English). finishing.com. Retrieved on November 29, 2006.
This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.