Barium carbonate
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2008-07-11T10:14:48Z
Metodicar
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/* References */ Interwiki-sr
{{Chembox new
| Name = Barium carbonate
| ImageFile=Barium carbonate.png
| ImageSize=120px
| OtherNames = witherite
| Section1 = {{Chembox Identifiers
| CASNo = 513-77-9
}}
| Section2 = {{Chembox Properties
| Formula = BaCO<sub>3</sub>
| MolarMass = 197.336 g/mol
| Appearance = white crystals
| Density = 4.2865 g/cm<sup>3</sup>, solid
| Solubility = .002 g/100 ml (20 °C)
| MeltingPt = 811 °C
| BoilingPt = 1555 °C
}}
}}
'''Barium carbonate''' ([[Barium|Ba]][[Carbonate|CO]]<sub>3</sub>), also known as '''witherite''', is a [[chemical]] compound used in [[rat poison]], [[brick]]s and [[cement]].
Witherite crystallizes in the orthorhombic system. The [[crystal]]s 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, Cumbria|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 [[salt]]s 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 [[chrome plating|chromium]] [[electroplating]] baths.<ref>{{cite web
| last = Whitelaw
| first = G.P.
| coauthors =
| title = Standard Chrome Bath Control
| work =
| pages =
| language = English
| publisher = finishing.com
| date = [[2003-10-25]]
| url = http://www.finishing.com/Library/Whitelawchrome.html
| accessdate = 2006-11-29 }}</ref>
==Reactions==
Barium carbonate reacts with many acids to soluble barium salts, for example [[barium chloride]]:
:BaCO<sub>3</sub>([[Solid|s]]) + 2 [[Hydrochloric acid|HCl]]([[Aqueous|aq]]) → [[Barium chloride|BaCl<sub>2</sub>]](aq) + [[Carbon dioxide|CO<sub>2</sub>]]([[Gas|g]]) + [[Water (molecule)|H<sub>2</sub>O]]([[Liquid|l]])
However the reaction with [[sulfuric acid]] is poor, because [[barium sulfate]] is highly [[Solubility|insoluble]].
==References==
<references />
* {{1911}}
[[Category:Barium compounds]]
[[Category:Carbonates]]
[[Category:Pyrotechnic colorants]]
[[ar:كربونات باريوم]]
[[bs:Barijum karbonat]]
[[de:Bariumcarbonat]]
[[it:Carbonato di bario]]
[[lv:Bārija karbonāts]]
[[nl:Bariumcarbonaat]]
[[ja:炭酸バリウム]]
[[pt:Carbonato de bário]]
[[sr:Баријум-карбонат]]
[[zh:碳酸钡]]