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A phosphate, an inorganic chemical, is a salt of phosphoric acid
Phosphoric acid

Phosphoric acid, also known as orthophosphoric acid or phosphoric acid, is a mineral acid having the chemical formula Hydrogen3PhosphorusOxygen4....
. Inorganic phosphates are mined
Mining

Mining is the extraction of value minerals or other geology materials from the earth, usually from an ore body, vein or seam. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, Sodium chloride and potash....
 to obtain phosphorus
Phosphorus

Phosphorus is the chemical element that has the symbol P and atomic number 15. The name comes from the and . A Valency nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate minerals....
 for use in agriculture and industry. In organic chemistry
Organic chemistry

Organic chemistry is a discipline within chemistry which involves the science study of the structure, properties, composition, chemical reaction, and preparation of chemical compounds that contain carbon....
, a phosphate, or organophosphate
Organophosphate

An organophosphate is the general name for esters of phosphoric acid. Phosphates are probably the most pervasive organophosphorus compounds. Many of the most important biochemicals are organophosphates, including DNA and RNA as well as many cofactor s that are essential for life....
, is an ester
Ester

An ester is an often Aroma compound organic chemistry or partially organic compound formed by the reaction between an acid and an alcohol or aromatic alcohol with the elimination of water....
 of phosphoric acid. Organic phosphates are important in biochemistry
Biochemistry

Biochemistry is the study of the chemistry processes in living organisms. It deals with the structure and function of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules....
 and biogeochemistry
Biogeochemistry

The field of biogeochemistry involves science of the chemistry, physics, geology, and biology processes and reactions that govern the composition of the natural environment , and the cycles of matter and energy that transport the Earth's chemical components in time and space....
.

phosphate ion is a polyatomic ion
Polyatomic ion

A polyatomic ion, also known as a molecular ion, is a charged species composed of two or more atoms Covalent bond or of a complex that can be considered as acting as a single unit in the context of acid and Base chemistry or in the formation of salt ....
 with the empirical formula
Empirical formula

In chemistry, the empirical formula of a chemical compound is a complex expression of the relative numbers of each type of atom in it. An empirical formula makes references to isomerism, structure, or absolute number of atoms....
 P
Phosphorus

Phosphorus is the chemical element that has the symbol P and atomic number 15. The name comes from the and . A Valency nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate minerals....
O
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
43- and a molar mass
Molar mass

Molar mass, symbol M, is the mass of one mole of a substance . It is a physical property which is characteristic of each pure substance. The base SI unit for mass is the kilogram but, for both practical and historical reasons, molar masses are almost always quoted in grams per mole , especially in chemistry....
 of 94.973 g/mol; it consists of one central phosphorus
Phosphorus

Phosphorus is the chemical element that has the symbol P and atomic number 15. The name comes from the and . A Valency nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate minerals....
 atom surrounded by four identical oxygen atoms in a tetrahedral
Tetrahedron

A tetrahedron is a polyhedron composed of four triangle faces, three of which meet at each vertex . A regular tetrahedron is one in which the four triangles are regular, or "equilateral", and is one of the Platonic solids....
 arrangement.






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A phosphate, an inorganic chemical, is a salt of phosphoric acid
Phosphoric acid

Phosphoric acid, also known as orthophosphoric acid or phosphoric acid, is a mineral acid having the chemical formula Hydrogen3PhosphorusOxygen4....
. Inorganic phosphates are mined
Mining

Mining is the extraction of value minerals or other geology materials from the earth, usually from an ore body, vein or seam. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, Sodium chloride and potash....
 to obtain phosphorus
Phosphorus

Phosphorus is the chemical element that has the symbol P and atomic number 15. The name comes from the and . A Valency nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate minerals....
 for use in agriculture and industry. In organic chemistry
Organic chemistry

Organic chemistry is a discipline within chemistry which involves the science study of the structure, properties, composition, chemical reaction, and preparation of chemical compounds that contain carbon....
, a phosphate, or organophosphate
Organophosphate

An organophosphate is the general name for esters of phosphoric acid. Phosphates are probably the most pervasive organophosphorus compounds. Many of the most important biochemicals are organophosphates, including DNA and RNA as well as many cofactor s that are essential for life....
, is an ester
Ester

An ester is an often Aroma compound organic chemistry or partially organic compound formed by the reaction between an acid and an alcohol or aromatic alcohol with the elimination of water....
 of phosphoric acid. Organic phosphates are important in biochemistry
Biochemistry

Biochemistry is the study of the chemistry processes in living organisms. It deals with the structure and function of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules....
 and biogeochemistry
Biogeochemistry

The field of biogeochemistry involves science of the chemistry, physics, geology, and biology processes and reactions that govern the composition of the natural environment , and the cycles of matter and energy that transport the Earth's chemical components in time and space....
.

Chemical properties


Phosphate Group
The phosphate ion is a polyatomic ion
Polyatomic ion

A polyatomic ion, also known as a molecular ion, is a charged species composed of two or more atoms Covalent bond or of a complex that can be considered as acting as a single unit in the context of acid and Base chemistry or in the formation of salt ....
 with the empirical formula
Empirical formula

In chemistry, the empirical formula of a chemical compound is a complex expression of the relative numbers of each type of atom in it. An empirical formula makes references to isomerism, structure, or absolute number of atoms....
 P
Phosphorus

Phosphorus is the chemical element that has the symbol P and atomic number 15. The name comes from the and . A Valency nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate minerals....
O
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
43- and a molar mass
Molar mass

Molar mass, symbol M, is the mass of one mole of a substance . It is a physical property which is characteristic of each pure substance. The base SI unit for mass is the kilogram but, for both practical and historical reasons, molar masses are almost always quoted in grams per mole , especially in chemistry....
 of 94.973 g/mol; it consists of one central phosphorus
Phosphorus

Phosphorus is the chemical element that has the symbol P and atomic number 15. The name comes from the and . A Valency nonmetal of the nitrogen group, phosphorus is commonly found in inorganic phosphate minerals....
 atom surrounded by four identical oxygen atoms in a tetrahedral
Tetrahedron

A tetrahedron is a polyhedron composed of four triangle faces, three of which meet at each vertex . A regular tetrahedron is one in which the four triangles are regular, or "equilateral", and is one of the Platonic solids....
 arrangement. The phosphate ion carries a negative three formal charge and is the conjugate base
Conjugate acid

Within the Johannes Nicolaus Br?nsted-Martin Lowry theory of acid-base reaction theories, a conjugate acid is the acid member, HX, of a pair of two compounds that transform into each other by gain or loss of a proton....
 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
Phosphoric acid

Phosphoric acid, also known as orthophosphoric acid or phosphoric acid, is a mineral acid having the chemical formula Hydrogen3PhosphorusOxygen4....
. It is a hypervalent molecule
Hypervalent molecule

A hypervalent molecule is a molecule that contains one or more typical elements formally bearing more than eight electrons in their valence shells....
 (the phosphorus atom has 10 electrons in its valence shell). Phosphate is also an organophosphorus
Organophosphorus

Organophosphorus compounds are chemical compounds containing carbon-phosphorus chemical bond, primarily used in pest control and are often persistent organic pollutants....
 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
Chemical compound

A chemical compound is a Chemical substance consisting of two or more different chemical element Chemical bond together in a fixed mass ratio that can be split into simpler substances....
. Many phosphates are not soluble
Solubility

Solubility is often seen as a property of a substance; for instance the solubility of a solid substance usually refers to the concentration of the substance in a liquid that has reached equilibrium with the substance in solid phase ....
 in water
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
 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 pyrophosphate
Pyrophosphate

In chemistry, the anion, the salts, and the esters of pyrophosphoric acid are called pyrophosphates. Pyrophosphates were originally prepared by heating phosphates: the prefix pyro- derived from Greek, means "fire" in this context....
s 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.

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
Phosphoric acid

Phosphoric acid, also known as orthophosphoric acid or phosphoric acid, is a mineral acid having the chemical formula Hydrogen3PhosphorusOxygen4....
):

(pKa1 2.16)


(pKa2 7.21)
(pKa3 12.32)


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



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

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



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



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

Phosphate can form many polymeric ions such as diphosphate (also pyrophosphate
Pyrophosphate

In chemistry, the anion, the salts, and the esters of pyrophosphoric acid are called pyrophosphates. Pyrophosphates were originally prepared by heating phosphates: the prefix pyro- derived from Greek, means "fire" in this context....
), P2O74-, and triphosphate, P3O105-. The various metaphosphate
Metaphosphate

A metaphosphate is a salt or an ester of metaphosphoric acid, HPO3.Metaphosphates are condensation products of orthophosphoric acid with the sum formula n....
 ions have an empirical formula of PO3- and are found in many compounds.

Phosphate deposits can contain significant amounts of naturally occurring uranium
Uranium

Uranium is a silvery-gray metallic chemical element in the actinide series of the periodic table that has the chemical symbol U and atomic number 92....
. Uptake of these substances by plants can lead to high uranium concentrations in crops.

Cellular function


Phosphate is useful in animal cells
Cell (biology)

The cell is the structural and functional unit of all known Life organisms. It is the smallest unit of an organism that is classified as living, and is often called the building bricks of life....
 as a buffering agent
Buffering agent

A buffering agent adjusts the pH of a solution. The function of a buffering agent is to drive an acidic or basic solution to a certain pH state and prevent a change in this pH....
. Phosphate salts that are commonly used for preparing buffer solutions at cell pHs include Na2HPO4 , NaH2PO4 , and the corresponding potassium salts.

Mining

Rock phosphate
Rock phosphate

Rock phosphate is a general term for rock that contains a high concentration of phosphate minerals, which commonly belong to the apatite group. Phosphate rock minerals are the only significant global resources of phosphorus....
 or phosphorite
Phosphorite

A phosphorite or phosphate rock is a non-detrital sedimentary rock which contains high amounts of phosphate bearing minerals. The phosphate content of phosphorite is at least 20% which is a large enrichment over the typical sedimentary rock content of less than 0.2%....
 mines are primarily found in: North America
  • United States of America, especially Florida
    Florida

    Florida is a U.S. state located in the Southeastern United States of the United States, bordering Alabama to the northwest and Georgia to the northeast....
    , with lesser deposits in North Carolina
    North Carolina

    North Carolina is a U.S. state located on the Atlantic Seaboard in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north....
    , Idaho
    Idaho

    The State of Idaho is a U.S. state in the Pacific Northwest region of the United States of America. The state's largest city and Capital is Boise, Idaho....
     and Tennessee
    Tennessee

    Tennessee is a U.S. state located in the Southern United States United States. In 1796, it became the sixteenth state to join the United States....
    .


Africa
  • Morocco
    Morocco

    Morocco , officially the Kingdom of Morocco , is a country located in North Africa with a population of nearly 34 million and an area just under 447,000 km2....
     mainly near Khouribga
    Khouribga

    Khouribga is a city in the Chaouia-Ouardigha region of Morocco with a population of approximately 172,000. Khouribga owes its growth to the phosphate deposits nearby....
     and Youssoufia and Western Sahara
    Western Sahara

    Western Sahara is a territory of North Africa, bordered by Morocco to the north, Algeria in the northeast, Mauritania to the east and south, and the Atlantic Ocean on the west....
  • Senegal
    Senegal

    Senegal , officially the Republic of Senegal, is a country south of the S?n?gal River in West Africa. Senegal is bounded by the Atlantic Ocean to the west, Mauritania to the north, Mali to the east, and Guinea and Guinea-Bissau to the south....
  • Tunisia
    Tunisia

    Tunisia , officially the Tunisian Republic , is a country located in North Africa. It is bordered by Algeria to the west and Libya to the southeast....


Oceania
  • Australia
    Australia

    Australia, officially the Commonwealth of Australia, is a country in the southern hemisphere comprising the Australia of the world's smallest continent, the major island of Tasmania, and numerous list of islands of Australia in the Indian Ocean and Pacific Oceans....
  • Makatea
    Makatea

    Makatea, or Mangaia-te-vai-tamae, is a Tectonic uplift coral island in the northwestern part of the Tuamotus. It is located 79 km southwest from Rangiroa to the west of the Palliser Islands group....
  • Nauru
    Nauru

    Nauru , officially the Republic of Nauru and formerly known as Pleasant Island, is an island nation in the Micronesian Pacific Ocean....
  • Ocean Island
    Ocean Island

    Ocean Island is a name given to two unrelated islands in the Pacific Ocean:* Kure Atoll, the last atoll in the Hawaiian Islands chain.* Banaba Island, in Kiribati, an island mined until recently for its phosphate....


See also



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.


External links