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phosphate

  (fŏs'fāt') pronunciation
n.
  1. A salt or ester of phosphoric acid.
  2. A fertilizer containing phosphorus compounds.
  3. A soda fountain drink made by blending carbonated water with flavored syrup.

[PHOSPH(O)– + –ATE2.]

phosphatic phos·phat'ic (fŏs-făt'ĭk) adj.
 
 
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

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.

 

Any of numerous chemical compounds related to phosphoric acid (H3PO4). Phosphate salts are inorganic compounds containing the phosphate ion (PO43-), the hydrogen phosphate ion (HPO42-), or the dihydrogen phosphate ion (H2PO4-), along with any cation. Phosphate esters are organic compounds in which the hydrogens of phosphoric acid are replaced by organic groups (e.g., methyl, ethyl, phenyl), with one of their carbon atoms bonding to an oxygen atom in the phosphate group. Nucleic acids and ATP both contain phosphate; bones and teeth contain calcium phosphate. Phosphate rock (mainly calcium phosphate) is one of the four most important basic chemical commodities. Phosphates were formerly used in detergents, which washed into rivers and lakes, causing water blooms of algae and bacteria (see eutrophication); such use is now generally outlawed or regulated. Phosphates are still used in fertilizers, baking powder, and toothpaste.

For more information on phosphate, visit Britannica.com.

 

(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.

 
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.


 

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, in inorganic chemistry, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Phosphates are important in biochemistry and biogeochemistry.

Chemical properties

The general chemical structure of a phosphate
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The general chemical structure of a phosphate
This is the structural formula of the phosphoric acid functional group as found in a weakly acidic aqueous solution. In more basic aqueous solutions, the group will donate the two hydrogen atoms and ionize as a phosphate group with a negative charge of 2. [1]
Enlarge
This is the structural formula of the phosphoric acid functional group as found in a weakly acidic aqueous solution. In more basic aqueous solutions, the group will donate the two hydrogen atoms and ionize as a phosphate group with a negative charge of 2. [1]

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 hydrogenphosphate 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 insoluble in water at standard temperature and pressure, except for the alkali metal salts.

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.

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}

K_{a2}=\frac{[\mbox{H}^+][\mbox{HPO}_4^{2-}]}{[\mbox{H}_2\mbox{PO}_4^-]}\simeq 6.2\times10^{-8}

K_{a3}=\frac{[\mbox{H}^+][\mbox{PO}_4^{3-}]}{[\mbox{HPO}_4^{2-}]}\simeq 2.14\times10^{-13}

For a strongly-basic pH (pH=13), we find

\frac{[\mbox{H}_2\mbox{PO}_4^-]}{[\mbox{H}_3\mbox{PO}_4]}\simeq 7.5\times10^{10}  \mbox{ , }\frac{[\mbox{HPO}_4^{2-}]}{[\mbox{H}_2\mbox{PO}_4^-]}\simeq 6.2\times10^5 \mbox{ , } \frac{[\mbox{PO}_4^{3-}]}{[\mbox{HPO}_4^{2-}]}\simeq 2.14

showing that only PO43− and HPO42− are in significant amounts.

For a neutral pH (for example the cytosol pH=7.0), we find

\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}

so that only H2PO4 and HPO42− ions are in significant amounts (62% H2PO4, 38% HPO42−). Note that in the extracellular fluid (pH=7.4), this proportion is inverted (61% HPO42−, 39% H2PO4).

For a strongly-acid pH (pH=1), we find

\frac{[\mbox{H}_2\mbox{PO}_4^-]}{[\mbox{H}_3\mbox{PO}_4]}\simeq 0.075 \mbox{ , }\frac{[\mbox{HPO}_4^{2-}]}{[\mbox{H}_2\mbox{PO}_4^-]}\simeq 6.2\times10^{-7} \mbox{ , } \frac{[\mbox{PO}_4^{3-}]}{[\mbox{HPO}_4^{2-}]}\simeq 2.14\times10^{-12}

showing that H3PO4 is dominant with respect to H2PO4. HPO42− and PO43− are practically absent.

Phosphate can form many polymeric ions, diphosphate (also pyrophosphate), P2O74−, triphosphate, P3O105−, et cetera. The various metaphosphate ions have an empirical formula of PO3 and are found in many compounds.

Phosphate deposits can contain significant amounts of naturally-occurring uranium. Subsequent uptake of such soil amendments can lead to crops containing puppy concentrations.

Occurrence

Shown is a sample of phosphate rock alongside a United States one-cent coin (for scale).
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Shown is a sample of phosphate rock alongside a United States one-cent coin (for scale).

Phosphates are the naturally-occurring form of the element phosphorus, found in many phosphate minerals. Elemental phosphorus and phosphides are not found (rare phosphide minerals may be found in meteorites). In mineralogy and geology, phosphate refers to a rock or ore containing phosphate ions.

The largest rock phosphate deposits in North America lie in the Bone Valley region of central Florida, United States, the Soda Springs region of Idaho, and the coast of North Carolina. Smaller deposits are located in Montana, Tennessee, Georgia, and South Carolina near Charleston along Ashley Phosphate road. The small island nation of Nauru and its neighbor Banaba Island, which used to have massive phosphate deposits of the best quality, have been mined excessively. Rock phosphate can also be found on Egypt, Israel, Morocco, Navassa Island, Tunisia, Togo, and Jordan have large phosphate mining industries as well.

In biological systems, phosphorus is found as a free phosphate ion in solution, and is called inorganic phosphate, to distinguish it from phosphates bound in various phosphate esters. Inorganic phosphate is generally denoted Pi, and can be created by the hydrolysis of pyrophosphate, which is denoted PPi:

P2O74− + H2O → 2HPO42−

However, phosphates are most commonly found in the form of adenosine phosphates (AMP, ADP, and ATP) and in DNA and RNA, and can be released by the hydrolysis of ATP or ADP. Similar reactions exist for the other nucleoside diphosphates and triphosphates. Phosphoanhydride bonds in ADP and ATP, or other nucleoside diphosphates and triphosphates, contain high amounts of energy, which give them their vital role in all living organisms. They are generally referred to as high-energy phosphate, as are the phosphagens in muscle tissue. Compounds, such as substituted phosphines, have uses in organic chemistry, but do not seem to have any natural counterparts.

In ecological terms, because of its important role in biological systems, phosphate is a highly-sought-after resource. As a consequence, it is often a limiting reagent in environments, and its availability may govern the rate of growth of organisms. Addition of high levels of phosphate to environments and to micro-environments in which it is typically rare can have significant ecological consequences, for example, booms in the populations of some organisms at the expense of others and the collapse of populations deprived of resources such as oxygen (see eutrophication). In the context of pollution, phosphates are a principal component of total dissolved solids, a major indicator of water quality.

Uses

The image above shows the annual mean sea surface phosphate concentrations for the World Ocean.  Data from the World Ocean Atlas 2001.[1]
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The image above shows the annual mean sea surface phosphate concentrations for the World Ocean. Data from the World Ocean Atlas 2001.[1]

Phosphates were once commonly used in laundry detergent in the form trisodium phosphate (TSP), but, because of algae boom-bust cycles tied to emission of phosphates into watersheds, phosphate detergent sale or usage is restricted in some areas.

In agriculture, phosphate is one of the three primary plant nutrients, and it is a component of fertilizers. Rock phosphate is quarried from phosphate beds in sedimentary rocks. In former times, it was simply crushed and used as is, but the crude form is now used only in organic farming. Normally, it is chemically treated to make superphosphate, triple superphosphate, or ammonium phosphates, which have higher concentration of phosphate and are also more soluble, therefore more quickly usable by plants.

Fertilizer grades have three numbers; the first is the available nitrogen, the second is the available phosphate (expressed on a P2O5 basis), and the third is the available potash (expressed on a K2O basis). Thus a 10-10-10 fertilizer would contain ten percent of each, with the remainder being filler.

Surface runoff of phosphates from excessively-fertilized farmland can be a cause of phosphate pollution, leading to eutrophication (nutrient enrichment), algal bloom, and consequent oxygen deficit. This can lead to anoxia for fish and other aquatic organisms in the same manner as phosphate-based detergents.

Phosphate compounds are occasionally added to the public drinking water supply to counter plumbosolvency.

The food industry uses phosphates to perform several different functions. For example, in meat products, it solubilizes the protein. This improves its water-holding ability and increases its moistness and succulence. In baked products, such as cookies and crackers, phosphate compounds can act as part of the leavening system when it reacts with an alkalai, usually sodium bicarbonate (baking soda).[1]

See also

caca moulu

References

  1. ^ On-line Objective Analyses and Statistics (HTML/ASCII). World Ocean Atlas 2001. National Oceanographic Data Center, National Oceanographic and Atmospheric Administration (2003).

3. "Figuring Out Phosphates," Food Product Design, June 2006, Lynn A. Kuntz

Further reading

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.


 
Translations: Translations for: Phosphate

Dansk (Danish)
n. - fosfat

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.)

Русский (Russian)
фосфат

Español (Spanish)
n. - fosfato

Svenska (Swedish)
n. - fosfat

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
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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Veterinary Dictionary. Saunders Comprehensive Veterinary Dictionary 3rd Edition. Copyright © 2007 by D.C. Blood, V.P. Studdert and C.C. Gay, Elsevier. All rights reserved.  Read more
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