Magnesium carbonate 383220 223887897 2008-07-06T10:16:00Z 222.166.160.141 /* Forms */ {{Chembox new | Name = Magnesium carbonate | ImageFile=Magnesium carbonate.png | ImageSize=120px | OtherNames = [[Magnesite]]<br />dihydrate: [[Barringtonite]]<br />trihydrate: [[Nesequehonite]]<br />pentahydrate: [[Lansfordite]]<Br/>White gold: | Name = Safety data | Section1 = {{Chembox Identifiers | CASNo = 546-93-0 | RTECS = OM2470000 }} | Section2 = {{Chembox Properties | Formula = MgCO<sub>3</sub> | MolarMass = 84.32 g/mol | Appearance = white solid | Density = 2.958 g/cm<sup>3</sup>, solid | Solubility = 10.6 mg/100 ml | MeltingPt = 350 °C ''decomp.'' }} | Section3 = {{Chembox Structure | Coordination = | CrystalStruct = [[Trigonal]] }} | Section4 = {{Chembox Thermochemistry | DeltaHf = -1111.69 kJ/mol | Entropy = 65.84 J.K<sup>&minus;1</sup>.mol<sup>&minus;1</sup> }} | Section8 = {{Chembox Related | OtherCations = [[Calcium carbonate]]<br />[[Strontium carbonate]]<br />[[Barium carbonate]] | OtherCpds = [[Artinite]]<br />[[Hydromagnesite]]<br />[[Dypingite]]}} }} '''Magnesium carbonate''', MgCO<sub>3</sub>, is a white [[solid]] that occurs in nature as a [[mineral]]. Several [[hydrated]] and [[Base (chemistry)|basic]] forms of magnesium carbonate also exist as [[mineral]]s. In addition, MgCO<sub>3</sub> has a variety of applications. ==Forms== The most common magnesium carbonate forms are the [[anhydrous]] salt called ''[[magnesite]]'' (MgCO<sub>3</sub>) and the di, tri, and pentahydrates known as ''barringtonite'' (MgCO<sub>3</sub>·2H<sub>2</sub>O), ''nesquehonite'' (MgCO<sub>3</sub>·3H<sub>2</sub>O), and ''lansfordite'' (MgCO<sub>3</sub>·5H<sub>2</sub>O), respectively. Some basic forms such as ''artinite'' (MgCO<sub>3</sub>·Mg(OH)<sub>2</sub>·3H<sub>2</sub>O), ''hydromagnestite'' (4MgCO<sub>3</sub>·Mg(OH)<sub>2</sub>·4H<sub>2</sub>O), and ''dypingite'' (4MgCO<sub>3</sub>· Mg(OH)<sub>2</sub>·5H<sub>2</sub>O) also occur as [[minerals]]. Magnesite consists of white [[trigonal]] [[crystals]]. The [[anhydrous]] salt is practically [[insoluble]] in [[water]], [[acetone]], and [[ammonia]]. All forms of magnesium carbonate react in [[acids]]. Magnesium carbonate crystallizes in the [[calcite]] structure where in [[magnesium|Mg<sup>2+</sup>]] is surrounded by six [[oxygen]] atoms. The dihydrate one has a [[triclinic]] structure, while the trihydrate has a [[monoclinic]] structure. References to 'light' and 'heavy' magnesium carbonates actually refer to the magnesium hydroxy carbonates [[hydromagnesite]] and [[dypingite]] (respectively)<ref>A. BOTHA and C. A. STRYDOM; “Preparation of a magnesium hydroxy carbonate from magnesium hydroxide;” Hydrometallurgy; Elsevier Science; December 2001; 62 (3): pp. 175–183.</ref>. <!-- ==Properties== Magnesium carbonate has properties as given in this article. --> ==Reactions== Although magnesium carbonate is ordinarily obtained by mining the mineral magnesite, the trihydrate salt, MgCO<sub>3</sub>·3H<sub>2</sub>O, can be prepared by mixing [[solutions]] of [[magnesium]] and [[carbonate]] [[ions]] under an atmosphere of [[carbon dioxide]]. Magnesium carbonate can also be synthesized by exposing a [[magnesium hydroxide]] slurry to [[carbon dioxide]] under [[pressure]] (3.5 to 5 atm) below 50 °C, which gives soluble magnesium bicarbonate: ::Mg(OH)<sub>2</sub> + 2 CO<sub>2</sub> → Mg(HCO<sub>3</sub>)<sub>2</sub><br /> Following the filtration of the solution, the filtrate is dried under vacuum to produce magnesium carbonate as a hydrated salt: ::Mg<sup>2+</sup> + 2 HCO<sub>3</sub><sup>-</sup> → MgCO<sub>3</sub> + CO<sub>2</sub> + H<sub>2</sub>O<br /> When dissolved with [[acid]], magnesium carbonate decomposes with release of [[carbon dioxide]]: ::MgCO<sub>3</sub> + 2 HCl → MgCl<sub>2</sub> + CO<sub>2</sub> + H<sub>2</sub>O<br /> ::MgCO<sub>3</sub> + H<sub>2</sub>SO<sub>4</sub> → MgSO<sub>4</sub> + CO<sub>2</sub> + H<sub>2</sub>O<br /> At high temperatures (800C-1000C), MgCO<sub>3</sub> decomposes to [[magnesium oxide]] and [[carbon dioxide]] with reaction [[enthalpy]] 118 kJ / mole, this process is called [[calcining]]: ::MgCO<sub>3</sub> → MgO + CO<sub>2</sub><br /> ==Uses== Magnesite and [[dolomite]] [[minerals]] are used to produce [[magnesium]] metal and basic refractory bricks. MgCO<sub>3</sub> is also used in flooring, fireproofing, fire extinguishing compositions, cosmetics, dusting powder, and toothpaste. Other applications are as filler material, smoke suppressant in plastics, a reinforcing agent in neoprene rubber, a drying agent, a laxative to loosen the bowels, and color retention in foods. In addition, high purity magnesium carbonate is used as [[antacid]] and as an additive in table salt to keep it free flowing. Because of its water-insoluble, [[hygroscopy|hygroscopic]] properties MgCO<sub>3</sub> was first added to salt in [[1911]] to make the salt flow more freely. The [[Morton Salt]] company adopted the slogan "When it rains it pours" in reference to the fact that its MgCO<sub>3</sub>-containing salt would not stick together in wet weather.<ref>{{cite web |title=Morton Salt FAQ |url=http://www.mortonsalt.com/faqs/index.html#q3 |access-date = 2007-05-14 }}</ref> Magnesium carbonate, most often referred to as 'chalk', is used as a drying agent for hands in [[rock climbing]], [[gymnastics]], and [[weight lifting]]. == Food additive == As a food additive it's known as E504. And the only known side effect is that it may work as a [[laxative]] in high concentrations. <ref>{{cite web|title=Food-Info.net : E-numbers : E504: Magnesium carbonates|url=http://www.food-info.net/uk/e/e504.htm}} 080419 food-info.net</ref> == References == <references/> *{{cite web | title = Magnesium Carbonate Light | work = Safety Data Sheet | publisher = Vet Way Limited | format = pdf | url = http://www.vet-way.com/liq-pow-pdfs-eng/Magnesium%20Carbonate%20Light.pdf | accessdate = 2008-01-06 }}<br /> *{{cite book | first = Pradyot | last = Patnaik | year = 2003 | title = Handbook of Inorganic Chemicals | publisher = McGraw Hill | location = New York }}<br /> *{{cite book | first = A.F "(ed.)" | last = Trotman-Dickenson | year = 1973 | title = Comprehensive Inorganic Chemistry | publisher = Pergamon Press | location = Oxford }}<br /> ==External links== *[http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc09/icsc0969.htm International Chemical Safety Card 0969] *[http://webbook.nist.gov/chemistry/ NIST Standard Reference Database] [[Category:Magnesium compounds]] [[Category:Carbonates]] [[cs:Uhličitan hořečnatý]] [[da:Magnesiumcarbonat]] [[de:Magnesiumcarbonat]] [[ja:炭酸マグネシウム]] [[pl:Węglan magnezu]] [[ru:Карбонат магния]] [[sk:Magnezit]] [[sr:Магнезијум карбонат]]