Monocalcium phosphate

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Monocalcium phosphate
Calcium dihydrogen phosphate.png
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IUPAC name
Calcium dihydrogen phosphate
Other names
Acid calcium phosphate
Calcium acid phosphate
Calcium diorthophosphate
Calcium biphosphate
Calcium superphosphate
Monobasic calcium phosphate
Monocalcium orthophosphate
Phosphoric acid, calcium salt (2:1)
3D model (JSmol)
ECHA InfoCard 100.028.943
E number E341(i) (antioxidants, ...)
PubChem CID
Molar mass 234.05 g/mol
AppearanceWhite powder
Density 2.220 g/cm3
Melting point 109 °C (228 °F; 382 K)
Boiling point 203 °C (397 °F; 476 K)(decomposes)
2 g/100 mL
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeMonocalcium phosphate
Flash point Non-flammable
Related compounds
Other anions
Calcium pyrophosphate
Other cations
Magnesium phosphate
Dicalcium phosphate
Tricalcium phosphate
Strontium phosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Monocalcium phosphate is an inorganic compound with the chemical formula Ca(H2PO4)2 ("AMCP" or "CMP-A" for anhydrous monocalcium phosphate). It is commonly found as the monohydrate ("MCP" or "MCP-M"), Ca(H2PO4)2·H2O. Both salts are colourless solids. They are used mainly as superphosphate fertilizers and are also popular leavening agents.. [1]



Material of relatively high purity, as required for baking, is produced by treating calcium hydroxide with phosphoric acid:

Ca(OH)2 + 2 H3PO4 → Ca(H2PO4)2 + 2 H2O

Samples of Ca(H2PO4)2 tend to convert to dicalcium phosphate:

Ca(H2PO4)2 → Ca(HPO4) + H3PO4


Use in fertilizers

Superphosphate fertilizers are produced by treatment of "phosphate rock" with acids. Using phosphoric acid, fluorapatite is converted to Ca(H2PO4)2:

Ca5(PO4)3F + 7 H3PO4 → 5 Ca(H2PO4)2 + HF

This solid is called triple superphosphate. Several million tons are produced annually for use as fertilizers. Residual HF typically reacts with silicate minerals co-mingled with the phosphate ores to produce hexafluorosilicic acid (H2SiF6). The majority of the hexafluorosilicic acid is converted to aluminium fluoride and cryolite for the processing of aluminium. [1] These materials are central to the conversion of aluminium ore into aluminium metal.

When sulfuric acid is used, the product contains phosphogypsum ( CaSO4·2H2O) and is called single superphosphate. [2]

Use as leavening agent

Calcium dihydrogen phosphate is used in the food industry as a leavening agent, i.e., to cause baked goods to rise. Because it is acidic, when combined with an alkali ingredient, commonly sodium bicarbonate (baking soda) or potassium bicarbonate, it reacts to produce carbon dioxide and a salt. Outward pressure of the carbon dioxide gas causes the rising effect. When combined in a ready-made baking powder, the acid and alkali ingredients are included in the right proportions such that they will exactly neutralize each other and not significantly affect the overall pH of the product. AMCP and MCP are fast acting, releasing most carbon dioxide within minutes of mixing. It is popularly used in pancake mixes. In double acting baking powders, MCP is often combined with the slow acting acid sodium acid pyrophosphate (SAPP). [3]

See also

Related Research Articles

Phosphoric acid chemical compound

Phosphoric acid is a weak acid with the chemical formula H
. Orthophosphoric acid refers to phosphoric acid, which is the IUPAC name for this compound. The prefix ortho- is used to distinguish the acid from related phosphoric acids, called polyphosphoric acids. Orthophosphoric acid is a non-toxic acid, which, when pure, is a solid at room temperature and pressure. The conjugate base of phosphoric acid is the dihydrogen phosphate ion, H
, which in turn has a conjugate base of hydrogen phosphate, HPO2−
, which has a conjugate base of phosphate, PO3−
. Phosphates are essential for life, being building blocks for both DNA and RNA.

Baking powder Dry chemical leavening agent

Baking powder is a dry chemical leavening agent, a mixture of a carbonate or bicarbonate and a weak acid. The base and acid are prevented from reacting prematurely by the inclusion of a buffer such as cornstarch. Baking powder is used to increase the volume and lighten the texture of baked goods. It works by releasing carbon dioxide gas into a batter or dough through an acid-base reaction, causing bubbles in the wet mixture to expand and thus leavening the mixture. The first single-acting baking powder was developed by Birmingham based food manufacturer Alfred Bird in England in 1843. The first double-acting baking powder was developed by Eben Norton Horsford in America in the 1860s.

A leaven, often called a leavening agent, is any one of a number of substances used in doughs and batters that cause a foaming action that lightens and softens the mixture. An alternative or supplement to leavening agents is mechanical action by which air is incorporated. Leavening agents can be biological or synthetic chemical compounds. The gas produced is often carbon dioxide, or occasionally hydrogen.

Ammonium bicarbonate chemical compound

Ammonium bicarbonate is an inorganic compound with formula (NH4)HCO3, simplified to NH5CO3. The compound has many names, reflecting its long history. Chemically speaking, it is the bicarbonate salt of the ammonium ion. It is a colourless solid that degrades readily to carbon dioxide, water and ammonia.

Bone ash is a white material produced by the calcination of bones. Typical bone ash consists of about 55.82% calcium oxide, 42.39% phosphorus pentoxide, and 1.79% water. The exact composition of these compounds varies depending upon the type of bones being used, but generally the formula for bone ash is: Ca5(OH)(PO4)3. Bone ash usually has a density around 3.10 g/mL and a melting point of 1670 °C (3038 °F). Most bones retain their cellular structure through calcination.

Calcium phosphate is a family of materials and minerals containing calcium ions (Ca2+) together with inorganic phosphate anions. Some so-called calcium phosphates contain oxide and hydroxide as well. They are white solids of nutritious value. Calcium phosphates are found in many living organisms, e.g., bone mineral and tooth enamel. In milk, it exists in a colloidal form in micelles bound to casein protein with magnesium, zinc, and citrate - collectively referred to as colloidal calcium phosphate (CCP). Various calcium phosphate minerals are used in the production of phosphoric acid and fertilizers. Overuse of certain forms of calcium phosphate can lead to nutrient-containing surface runoff and subsequent adverse effects upon receiving waters such as algal blooms and eutrophication.

Ammonium carbonate chemical compound

Ammonium carbonate is a salt with the chemical formula (NH4)2CO3. Since it readily degrades to gaseous ammonia and carbon dioxide upon heating, it is used as a leavening agent and also as smelling salt. It is also known as baker's ammonia and was a predecessor to the more modern leavening agents baking soda and baking powder. It is a component of what was formerly known as sal volatile and salt of hartshorn.

Monopotassium phosphate chemical compound

Monopotassium phosphate, MKP, (also potassium dihydrogenphosphate, KDP, or monobasic potassium phosphate) is the inorganic compound with the formula KH2PO4. Together with dipotassium phosphate (K2HPO4.(H2O)x) it is often used as a fertilizer, food additive, and buffering agent. The salt often cocrystallizes with the dipotassium salt as well as with phosphoric acid.

Acid salts are a class of salts that produce an acidic solution after being dissolved in a solvent. Its formation as a substance has a greater electrical conductivity than that of the pure solvent. An acidic solution formed by acid salt is made during partial neutralization of diprotic or polyprotic acids. A half-neutralization occurs due to the remaining of replaceable hydrogen atoms from the partial dissociation of weak acids that have not been reacted with hydroxide ions (OH) to create water molecules. Acid salt is an ionic compound consisted of an anion, contributed from a weak parent acid, and a cation, contributed from a strong parent base.

Carbothermic reactions involve the reduction of substances, often metal oxides, using carbon as the reducing agent. These chemical reactions are usually conducted at temperatures of several hundred degrees Celsius. Such processes are applied for production of the elemental forms of many elements. Carbothermic reactions are not useful for some metal oxides, such as those of sodium and potassium. The ability of metals to participate in carbothermic reactions can be predicted from Ellingham diagrams.

Dicalcium phosphate chemical compound CaHPO₄

Dicalcium phosphate is the calcium phosphate with the formula CaHPO4 and its dihydrate. The "di" prefix in the common name arises because the formation of the HPO42– anion involves the removal of two protons from phosphoric acid, H3PO4. It is also known as dibasic calcium phosphate or calcium monohydrogen phosphate. Dicalcium phosphate is used as a food additive, it is found in some toothpastes as a polishing agent and is a biomaterial.

Hexafluorosilicic acid Hexafluorosilicic acid

Hexafluorosilicic acid is an inorganic compound with the chemical formula (H
. It is a colorless liquid rarely encountered undiluted. Hexafluorosilicic acid has a distinctive sour taste and pungent smell. It is produced naturally on a large scale in volcanoes. It is manufactured as a coproduct in the production of phosphate fertilizers. The resulting hexafluorosilicic acid is almost exclusively consumed as a precursor to aluminum trifluoride and synthetic cryolite, which are used in aluminium processing. Salts derived from hexafluorosilicic acid are called hexafluorosilicates.

Dihydrogen phosphate

Dihydrogenphosphate or Dihydrogen phosphate or dihydrogenphosphate ion is an inorganic ion with the formula [H2PO4]-. Its formula can also be written as [PO2(OH)2]-, which shows the presence of two O-H bonds. Together with monohydrogen phosphate, dihydrogen phosphate occurs widely in natural systems. Their salts are used in fertilizers and in cooking. Most dihydrogenphosphate salts are colorless, water soluble, and nontoxic.

Dipotassium phosphate chemical compound

Dipotassium phosphate (K2HPO4) (also dipotassium hydrogen orthophosphate; potassium phosphate dibasic) is the inorganic compound with the formula K2HPO4.(H2O)x (x = 0, 3, 6). Together with monopotassium phosphate (KH2PO4.(H2O)x) it is often used as a fertilizer, food additive, and buffering agent.

Disodium pyrophosphate chemical compound

Disodium pyrophosphate or sodium acid pyrophosphate (SAPP) is an inorganic compound consisting of sodium cations and pyrophosphate anion. It is a white, water-soluble solid that serves as a buffering and chelating agent, with many applications in the food industry. When crystallized from water, it forms a hexahydrate, but it dehydrates above room temperature. Pyrophosphate is a polyvalent anion with a high affinity for polyvalent cations, e.g. Ca2+.

Disodium phosphate chemical compound Na2HPO4

Disodium phosphate (DSP), or sodium hydrogen phosphate, or sodium phosphate dibasic, is the inorganic compound with the formula Na2HPO4. It is one of several sodium phosphates. The salt is known in anhydrous form as well as forms with 2, 7, 8, and 12 hydrates. All are water-soluble white powders; the anhydrous salt being hygroscopic.

Monomagnesium phosphate chemical compound H₄MgO₈P₂

Monomagnesium phosphate is one of the forms of magnesium phosphate. It is a magnesium acid salt of phosphoric acid with the chemical formula Mg(H2PO4)2. Di- and tetrahydrates are known also. It dissolves in water, forming phosphoric acid and depositing a solid precipitate of Mg(HPO4).3H2O, dimagnesium phosphate.

Dimagnesium phosphate chemical compound HMgO₄P

Dimagnesium phosphate is a compound with formula MgHPO4. It is a Mg2+ salt of monohydrogen phosphate. The trihydrate is well known, occurring as a mineral.

Monohydrogen phosphate

Monohydrogen phosphate is the inorganic ion with the formula [HPO4]2-. Its formula can also be written as [PO3(OH)]2-, which shows the presence of a O-H bond. Together with dihydrogen phosphate, monhydrogen phosphate occurs widely in natural systems. Their salts are used in fertilizers and in cooking. Most monohydrogenphosphate salts are colorless, water soluble, and nontoxic.

Sodium aluminium phosphate (SAlP) describes the inorganic compounds consisting of sodium salts of aluminium phosphates. The most common SAlP has the formulas NaH14Al3(PO4)8·4H2O and Na3H15Al2(PO4)8. These materials are prepared by combining alumina, phosphoric acid, and sodium hydroxide.


  1. 1 2 Schrödter, Klaus; Bettermann, Gerhard; Staffel, Thomas; Wahl, Friedrich; Klein, Thomas; Hofmann, Thomas (2008). "Phosphoric Acid and Phosphates". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_465.pub3.
  2. Gunnar Kongshaug et al. "Phosphate Fertilizers" in Ullmann's Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim. doi : 10.1002/14356007.a19_421.pub2
  3. John Brodie, John Godber "Bakery Processes, Chemical Leavening Agents" in Kirk-Othmer Encyclopedia of Chemical Technology 2001, John Wiley & Sons. doi : 10.1002/0471238961.0308051303082114.a01.pub2

Further reading