Magnesium carbonate
You don't need to be Editor-In-Chief to add or edit content to WikiDoc. You can begin to add to or edit text on this WikiDoc page by clicking on the edit button at the top of this page. Next enter or edit the information that you would like to appear here. Once you are done editing, scroll down and click the Save page button at the bottom of the page.
| Safety data | |
|---|---|
| Image:Magnesium carbonate.png | |
| Other names | Magnesite dihydrate: Barringtonite trihydrate: Nesequehonite pentahydrate: Lansfordite White gold: |
| Identifiers | |
| CAS number | |
| RTECS number | OM2470000 |
| Properties | |
| Molecular formula | MgCO3 |
| Molar mass | 84.32 g/mol |
| Appearance | white solid |
| Density | 2.958 g/cm3, solid |
| Melting point |
350 °C decomp. |
| Solubility in water | 10.6 mg/100 ml |
| Structure | |
| Crystal structure | Trigonal |
| Thermochemistry | |
| Std enthalpy of formation ΔfH | -1111.69 kJ/mol |
| Standard molar entropy S | 65.84 J.K−1.mol−1 |
| Related Compounds | |
| Other cations | Calcium carbonate Strontium carbonate Barium carbonate |
| Related compounds | Artinite Hydromagnesite Dypingite |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references | |
Magnesium carbonate, MgCO3, is a white solid that occurs in nature as a mineral. Several hydrated and basic forms of magnesium carbonate also exist as minerals. In addition, MgCO3 has a variety of applications.
Properties
The most common magnesium carbonate forms are the anhydrous salt called magnesite (MgCO3) and the di, tri, and pentahydrates known as barringtonite (MgCO3·2H2O), nesquehonite (MgCO3·3H2O), and lansfordite (MgCO3·5H2O), respectively. Some basic forms such as artinite (MgCO3·Mg(OH)2·3H2O), hydromagnestite (4MgCO3·Mg(OH)2·4H2O), and dypingite (4MgCO3· Mg(OH)2·5H2O) 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 dissolve in acids. Magnesium carbonate crystallizes in the calcite structure wherein Mg2+ is surrounded by six oxygen atoms. The dihydrate has a triclinic structure, while the trihydrate has a monoclinic structure. The pentahydrate is a white crystalline solid with monoclinic crystals.
Reactions
Although magnesium carbonate is ordinarily obtained by mining the mineral magnesite, the trihydrate salt, MgCO3·3H2O, 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)2 + 2 CO2 → Mg(HCO3)2
- Mg(OH)2 + 2 CO2 → Mg(HCO3)2
Following the filtration of the solution, the filtrate is dried under vacuum to produce magnesium carbonate as a hydrated salt:
- Mg2+ + 2 HCO3- → MgCO3 + CO2 + H2O
- Mg2+ + 2 HCO3- → MgCO3 + CO2 + H2O
When dissolved with acid, magnesium carbonate decomposes with release of carbon dioxide:
- MgCO3 + 2 HCl → MgCl2 + CO2 + H2O
- MgCO3 + H2SO4 → MgSO4 + CO2 + H2O
- MgCO3 + 2 HCl → MgCl2 + CO2 + H2O
At high temperatures, MgCO3 decomposes to magnesium oxide and carbon dioxide, this process is called calcining:
- MgCO3 → MgO + CO2
- MgCO3 → MgO + CO2
Uses
Magnesite and dolomite minerals are used to produce magnesium metal and basic refractory bricks. MgCO3 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, hygroscopic properties MgCO3 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 MgCO3-containing salt would not stick together in wet weather.[1]
Magnesium carbonate, most often referred to as 'chalk', is used as a drying agent for hands in rock climbing, gymnastics, and weight lifting.
References
- Magnesium Carbonate Light (pdf). Safety Data Sheet. Vet Way Limited. Retrieved on 2008-01-06.
- Patnaik, Pradyot (2003). Handbook of Inorganic Chemicals. New York: McGraw Hill.
- Trotman-Dickenson, A.F "(ed.)" (1973). Comprehensive Inorganic Chemistry. Oxford: Pergamon Press.
External links
da:Magnesiumcarbonat de:Magnesiumcarbonat ja:炭酸マグネシウムsk:Magnezit sr:Магнезијум карбонат
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
