- A salt or ester of phosphoric acid.
- A fertilizer containing phosphorus compounds.
- A soda fountain drink made by blending carbonated water with flavored syrup.
[PHOSPH(O)– + –ATE2.]
phosphatic phos·phat'ic (fŏs-făt'ĭk) adj.
phosphate
Dictionary:
phos·phate (fŏs'fāt')  |
| Food and Nutrition: phosphates |
Salts of phosphoric acid; the form in which the element phosphorus is normally present in foods and body tissues. See also polyphosphates.
| Dental Dictionary: phosphates |
(fos′fāts)
n.pl
n.pl
The organic compounds of phosphorus. The blood phosphate level is normally 2.5 mg to 5 mg/100 mL. It is low in rickets and early hyperparathyroidism and high in tetany and nephritis.
| Britannica Concise Encyclopedia: phosphate |
For more information on phosphate, visit Britannica.com.
| Archaeology Dictionary: phosphate |
(phosphorus) [Ma]
Phosphates are naturally present in all soils at varying levels. Anthropogenically derived phosphates have their sources in a wide range of organic materials with the result that in occupation areas, burials, food-processing areas, latrine areas and animal compounds and droveways the phosphate levels in the soil can be considerably enhanced. Once in the soil, phosphate is generally fixed in an insoluble form to inorganic aluminium, calcium, and iron components, or associates with organic molecules to form insoluble complexes. Fixed in this way it can survive for long periods. In archaeology, identifying concentrations of phosphates through phosphate analysis is extremely useful for the recognition and definition of settlement sites, and mapping the different levels of activity within a site. Phosphates can also be used to identify the presence of burials in ground where all physical traces have vanished.
| Columbia Encyclopedia: phosphate |
phosphate, salt or ester of phosphoric acid, H3PO4. Because phosphoric acid is tribasic (having three replaceable hydrogen atoms), it forms monophosphate, diphosphate, and triphosphate salts in which one, two, or three of the hydrogens of the acid are replaced, respectively. Because replaceable hydrogens remain in monophosphates and diphosphates, they are sometimes called acid phosphates. The most important inorganic phosphate is calcium phosphate, Ca3(PO4)2. It makes up the larger part of phosphate rock, a mineral that is abundantly distributed throughout the world. Since calcium phosphate is only slightly soluble in water, it is not very suitable as a source of the phosphorus necessary for plant life; however, by treating it with sulfuric acid the soluble calcium acid phosphate known as superphosphate of lime is formed. Other important inorganic phosphates include ammonium phosphate, important as a fertilizer; trisodium phosphate, used in detergents and for softening water; and disodium phosphate, used to some extent in medicine and in preparing baking powders. Various acid phosphates, e.g., those of calcium, magnesium, and sodium, are sometimes present in carbonated beverages. Microcosmic salt, used in certain bead tests in chemical analysis, is sodium ammonium phosphate. Organic phosphates play an important role in metabolism. For example, in the metabolism of sugars (which have hydroxyl groups, [sbond]OH, in their molecules), phosphate esters are often formed as an intermediate compound. Formation of these esters is called phosphorylation. Nucleotides are phosphate esters that play an important role in the conservation and use of the energy released in the metabolism of foods in the body; adenosine triphosphate is an important nucleotide. DNA and RNA (see nucleic acid) are complex polymeric organic phosphates.
| Veterinary Dictionary: phosphate |
Any salt or ester of phosphoric acid.
1. Phosphates are widely distributed in the body, the largest amounts being in the bones and teeth. They are continually excreted in the urine and feces, and must be replaced in the diet. Inorganic phosphates function as buffer salts to maintain the acid–base balance in blood, saliva, urine and other body fluids. The principal phosphates in this buffer system are monosodium and disodium phosphate. Organic phosphates, in particular adenosine triphosphate (ATP), are used to store the chemical bond energy released during the oxidation of compounds such as glycogen or fatty acids, which may later be expended in muscle contraction. This is thought to occur through the hydrolysis of the so-called high-energy phosphate bond present in ATP, phosphocreatine and certain other body compounds. See also hypophosphatemia, hyperphosphatemia.
2. used extensively in agricultural industry as fertilizers and organic compounds as cleaning agents.
- p. binders — usually aluminum carbonate or hydroxide preparations, used to bind phosphates and limit their absorption from the intestine. Used in the treatment of the hyperphosphatemia of renal failure.
- p. buffer — important phosphate-containing buffers.
- p. buffered saline — a special phosphate buffered saline used in tissue cultures and for the storage and transport of bovine embryos. Abbreviated PBS.
- p. calculi — see struvite urolith.
- dietary p. — supplementation of the diet with phosphate in some form is a very common practice in farm animals. Materials used include rock phosphate (defluorination may be necessary), sodium dihydrogen phosphate produced by the agricultural chemical industry, calcium triphosphate and bone meal or flour.
- inorganic p. — any salt of phosphoric acid.
- p. retention — a phenomenon resulting from reduced glomerular filtration; contributes to a chronic hypocalcemic state.
- p. ridge — see mineralization front.
- p. rock — see rock phosphate.
- p. yielding endonucleases — a class of ribonuclease involved in the usually fairly rapid turnover of RNA in the cell that degrades RNA by cleavage of the phosphodiester bonds within the molecule.
| Wikipedia: Phosphate |
A phosphate, an inorganic chemical, is a salt of phosphoric acid. Inorganic phosphates are mined to obtain phosphorus for use in agriculture and industry.[1][2] In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry.
Contents |
Chemical properties
The phosphate ion is a polyatomic ion with the empirical formula PO43− and a molar mass of 94.973 g/mol. It consists of one central phosphorus atom surrounded by four identical oxygen atoms in a tetrahedral arrangement. The phosphate ion carries a negative three formal charge and is the conjugate base of the hydrogen phosphate ion, HPO42−, which is the conjugate base of H2PO4−, the dihydrogen phosphate ion, which in turn is the conjugate base of H3PO4, phosphoric acid. It is a hypervalent molecule (the phosphorus atom has 10 electrons in its valence shell). Phosphate is also an organophosphorus compound with the formula OP(OR)3. A phosphate salt forms when a positively-charged ion attaches to the negatively-charged oxygen atoms of the ion, forming an ionic compound. Many phosphates are not soluble in water at standard temperature and pressure. The sodium, potassium, rubidium, caesium and ammonium phosphates are all water soluble. Most other phosphates are only slightly soluble or are insoluble in water. As a rule, the hydrogenphosphates and the dihydrogenphosphates are slightly more soluble than the corresponding phosphates. The pyrophosphates are mostly water soluble.
In dilute aqueous solution, phosphate exists in four forms. In strongly-basic conditions, the phosphate ion (PO43−) predominates, whereas in weakly-basic conditions, the hydrogen phosphate ion (HPO42−) is prevalent. In weakly-acid conditions, the dihydrogen phosphate ion (H2PO4−) is most common. In strongly-acid conditions, aqueous phosphoric acid (H3PO4) is the main form.
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More precisely, considering the following three equilibrium reactions:
- H3PO4
H+ + H2PO4−
- H2PO4− H+ + HPO42−
- HPO42− H+ + PO43−
the corresponding constants at 25°C (in mol/L) are (see phosphoric acid):
![K_{a1}=\frac{[\mbox{H}^+][\mbox{H}_2\mbox{PO}_4^-]}{[\mbox{H}_3\mbox{PO}_4]}\simeq 7.5\times10^{-3}](http://wpcontent.answers.com/math/e/6/9/e699884edcac6d95070a845c0c762a2d.png)
(pKa1 2.12)
![K_{a2}=\frac{[\mbox{H}^+][\mbox{HPO}_4^{2-}]}{[\mbox{H}_2\mbox{PO}_4^-]}\simeq 6.2\times10^{-8}](http://wpcontent.answers.com/math/4/6/6/466635c0bdeda7b6835c81ed05521c58.png)
(pKa2 7.21)![K_{a3}=\frac{[\mbox{H}^+][\mbox{PO}_4^{3-}]}{[\mbox{HPO}_4^{2-}]}\simeq 2.14\times10^{-13}](http://wpcontent.answers.com/math/5/c/c/5cc79605352c42f338e007c5d4c32db1.png)
(pKa3 12.67)
The speciation diagram obtained using these pK values shows three distinct regions. In effect H3PO4, H2PO4- and HPO42- behave as separate weak acids. This is because the successive pK values differ by more than 4. For each acid the pH at half-neutralization is equal to the pK value of the acid. The region in which the acid is in equilibrium with its conjugate base is defined by pH ≈ pK ± 2. Thus the three pH regions are approximately 0-4, 5-9 and 10-14. This is idealized as it assumes constant ionic strength, which will not hold in reality at very low and very high pH values.
For a neutral pH as in the cytosol, pH=7.0
![\frac{[\mbox{H}_2\mbox{PO}_4^-]}{[\mbox{H}_3\mbox{PO}_4]}\simeq 7.5\times10^4 \mbox{ , }\frac{[\mbox{HPO}_4^{2-}]}{[\mbox{H}_2\mbox{PO}_4^-]}\simeq 0.62 \mbox{ , } \frac{[\mbox{PO}_4^{3-}]}{[\mbox{HPO}_4^{2-}]}\simeq 2.14\times10^{-6}](http://wpcontent.answers.com/math/d/5/9/d5974fad8b424a36ef554a11bfe2243c.png)
so that only H2PO4− and HPO42− ions are present in significant amounts (62% H2PO4−, 38% HPO42−). Note that in the extracellular fluid (pH=7.4), this proportion is inverted (61% HPO42−, 39% H2PO4−).
Phosphate can form many polymeric ions such as diphosphate (also known aspyrophosphate), P2O74−, and triphosphate, P3O105−. The various metaphosphate ions (which are usually long linear polymers) have an empirical formula of PO3− and are found in many compounds.
Phosphate deposits can contain significant amounts of naturally occurring uranium. Uptake of these substances by plants can lead to high uranium concentrations in crops.
Cellular function
See also phosphorylation for more information on the use of phosphate by cells.
The addition and removal of phosphate from proteins in all cells is a pivotal strategy in the regulation of metabolic processes.
Phosphate is useful in animal cells as a buffering agent. Phosphate salts that are commonly used for preparing buffer solutions at cell pHs include Na2HPO4 , NaH2PO4 , and the corresponding potassium salts.
Mining
Rock phosphate or phosphorite mines are primarily found in:
- North America
- United States of America, especially North Carolina, with lesser deposits in Florida, Idaho and Tennessee.
- Africa
- Middle East
- Oceania
In 2007, at the current rate of consumption, the supply of phosphorus was estimated to run out in 345 years.[4] However, scientists are now claiming that a "Peak Phosphorus" will occur in 30 years and that "At current rates, reserves will be depleted in the next 50 to 100 years."[5]
See also
- Organophosphorus compounds
- Phosphate conversion coating
- Phosphine - PR3
- Phosphine oxide - OPR3
- Phosphinite - P(OR)R2
- Phosphonite - P(OR)2R
- Phosphite - P(OR)3
- Phosphinate - OP(OR)R2
- Phosphonate - OP(OR)2R
- Phosphate - OP(OR)3, such as triphenyl phosphate
- Polyphosphate - Pn
Further reading
 |
This article is in need of attention from an expert on the subject. WikiProject Chemicals may be able to help recruit one. (November 2008) |
- Schmittner Karl-Erich and Giresse Pierre, 1999. Micro-environmental controls on biomineralization: superficial processes of apatite and calcite precipitation in Quaternary soils, Roussillon, France. Sedimentology 46/3: 463-476.
References
- ^ Phosphate Primer, website of the Florida Institute of Phosphate Research
- ^ "Figuring Out Phosphates," Food Product Design, June 2006, Lynn A. Kuntz
- ^ Campbell, Neil A.; Reece, Jane B. (2005). Biology (Seventh ed.). San Francisco, California: Benjamin Cummings. pp. 65. ISBN 0-8053-7171-0.
- ^ "How Long Will it Last?". New Scientist 194 (2605): 38–39. May 26, 2007. ISSN 4079 0262 4079.
- ^ Leo Lewis (2008-06-23). "Scientists warn of lack of vital phosphorus as biofuels raise demand". The Times. http://business.timesonline.co.uk/tol/business/industry_sectors/natural_resources/article4193017.ece.
External links
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
| Translations: Phosphate |
Nederlands (Dutch)
fosfaat, (mv) fosfaatmest, prik (drank) met kleine hoeveelheid fosfaat
Français (French)
n. - (Chim) phosphate, (Agric) phosphates, engrais phosphatés
Deutsch (German)
n. - Phosphat
Ελληνική (Greek)
n. - (χημ.) φωσφορικό άλας
Italiano (Italian)
fosfato, concime fosfatico
Português (Portuguese)
n. - fosfato (m) (Quím.)
Español (Spanish)
n. - fosfato
中文（简体）(Chinese (Simplified))
磷酸盐, 磷酸果汁汽水, 磷肥
中文（繁體）(Chinese (Traditional))
n. - 磷酸鹽, 磷酸果汁汽水, 磷肥
한국어 (Korean)
n. - 인산염 , 인산 비료, 탄산수
日本語 (Japanese)
n. - リン酸塩, リン酸肥料, 炭酸飲料
العربيه (Arabic)
(الاسم) فسفات : ملح حامض الفسفوريك, سماد الفسفات
עברית (Hebrew)
n. - זרחה, פוספט
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 | Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved. Read more |
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| Food and Nutrition. A Dictionary of Food and Nutrition. Copyright © 1995, 2003, 2005 by A. E. Bender and D. A. Bender. All rights reserved. Read more |
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| Archaeology Dictionary. The Concise Oxford Dictionary of Archaeology. Copyright © 2002, 2003 by Oxford University Press. All rights reserved. Read more |
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