Calcium oxalate
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| Calcium oxalate | |
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| General | |
| Systematic name | calcium ethanedioate |
| Molecular formula | CaC2O4 |
| Molar mass | 128.10 g/mol, anhydrous 146.12 g/mol, monohydrate |
| Appearance | colourless solid |
| Properties | |
| Density and phase | 2.2 g/cm³, anhydrous 2.2 g/cm³, monohydrate |
| Solubility in water | 0.00067 g/100 ml (20 °C) |
| Melting point | decomposes |
| Heat of formation | -1360.6 kJ/mol (anyhdrous)[1] |
| Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references |
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Calcium oxalate is a chemical compound that forms needle-shaped crystals. Large quantities are found in the painfully poisonous plant dumb cane. It is also found in rhubarb leaves, various species of Oxalis, and agaves, and (in lower amounts) in spinach. Most kidney stones are caused by calcium oxalate.
Nonsoluble calcium oxalate crystals are found in plant stems, roots, and leaves. The stalk of the Dieffenbachia produces the most severe reactions. These needle-like crystals produce pain and edema when they contact lips, tongue, oral mucosa, conjunctiva, or skin. Oedema primarily is due to direct trauma from the needle-like crystals and, to a lesser extent, by other plant toxins (e.g. bradykinins, enzymes).
Even small doses of oxalate toxin is enough to cause intense sensations of burning in the mouth and throat, swelling, and choking. In larger doses, however, Oxalate causes severe digestive upset, breathing difficulties and - if enough is consumed - convulsions, coma and death. Recovery from severe oxalate poisoning is possible, but permanent liver and kidney damage may have occurred.
Calcium oxalate also forms a major component of beerstone, a brownish precipitate that tends to accumulate within vats, barrels and other containers used in the brewing of beer.[2] Beerstone is composed of calcium and magnesium salts and various organic compounds left over from the brewing process; it promotes the growth of unwanted microorganisms that can adversely affect or even ruin the flavor of a batch of beer.
Calcium oxalate crystal formation is also one of the toxic effects of ethylene glycol poisoning.
[edit] See also
[edit] References
- ^ Weast, R.C. 1974. Handbook of Chemistry and Physics, 54th edition. Chemical Rubber Publishing Company.
- ^ Johnson, Dana (1998-03-23). Removing Beerstone. Modern Brewery Age. Birko Corporation R&D. Retrieved on 2007-08-06.
[edit] External links
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