{{Chembox | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 462253577 | ImageFile1 = monosodium phosphate.png | ImageSize1 = 150px | ImageFile2 = Sodium-dihydrogen-phosphate-3D-vdW.png | ImageSize2 = 140px | ImageCaption2 = {{legend|orange|Phosphorus, P}}{{legend|red|Oxygen, O}}{{legend|white|Hydrogen, H}}{{legend|rgb(160, 84, 232)|Sodium, Na}} | ImageName2 = Ball-and-stick model of the dihydrogenphosphate anion | ImageFile3 = Dihydrogenfosforečnan sodný.JPG | IUPACName = Sodium dihydrogen phosphate | OtherNames = {{ubl|Monobasic sodium phosphate|Sodium biphosphate}} | Section1 = {{Chembox Identifiers | CASNo = 7558-80-7 | CASNo_Ref = {{cascite|correct|CAS}} | UNII_Ref = {{fdacite|changed|FDA}} | UNII = KH7I04HPUU | ChEMBL_Ref = {{ebicite|correct|EBI}} | ChEMBL = 1368 | PubChem = 24204 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 22626 | ChEBI_Ref = {{ebicite|correct|EBI}} | ChEBI = 37585 | SMILES = [Na+].[O-]P(=O)(O)O | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/Na.H3O4P/c;1-5(2,3)4/h;(H3,1,2,3,4)/q+1;/p-1 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = AJPJDKMHJJGVTQ-UHFFFAOYSA-M }} | Section2 = {{Chembox Properties | Formula = {{chem2|NaH2PO4}} | Na=1|H=2|P=1|O=4 | Appearance = White powder or crystals | Density = 2.36 g/cm<sup>3</sup> (anhydrous) | MeltingPt = | BoilingPt = | Solubility = 59.90 g/(100 mL) (0°C) }} | Section7 = {{Chembox Hazards | ExternalSDS = | NFPA-H = 0 | NFPA-F = 0 | NFPA-R = 0 | MainHazards = | FlashPt = Non-flammable }} | Section8 = {{Chembox Related | OtherAnions = | OtherCations = {{ubl|Monopotassium phosphate|Monoammonium phosphate}} | OtherCompounds = {{ubl|Disodium phosphate|Trisodium phosphate}} }} }} '''Monosodium phosphate''' ('''MSP'''), also known as '''monobasic sodium phosphate''' and '''sodium dihydrogen phosphate''', is an inorganic compound with the chemical formula {{chem2|NaH2PO4|auto=1}}. It is a sodium salt of phosphoric acid. It consists of sodium cations ({{chem2|Na+}}) and dihydrogen phosphate anions ({{chem2|H2PO4−}}). One of many sodium phosphates, it is a common industrial chemical. The salt exists in an anhydrous form, as well as monohydrate and dihydrate ({{chem2|NaH2PO4*H2O}} and {{chem2|NaH2PO4*2H2O}} respectively).<ref name=Ullmann>{{Ullmann|first1=Klaus|last1=Schrödter|first2=Gerhard|last2=Bettermann|first3=Thomas |last3=Staffel|first4=Friedrich|last4=Wahl|first5=Thomas|last5=Klein||first6=Thomas|last6=Hofmann|title=Phosphoric Acid and Phosphates|year=2008|doi=10.1002/14356007.a19_465.pub3}}</ref>
==Production and reactions== The salt is obtained by partial neutralization of phosphoric acid.
The p''K''<sub>a</sub> of monosodium phosphate is 6.8-7.2 (depending on the physicochemical characteristics during p''K''<sub>a</sub> determination).<ref>Salaun, F.: [http://www.prodinra.inra.fr/prodinra/pinra/data/2008/04/PROD2008990fa814_20080417115100287.pdf "Influence of mineral environment on the buffering capacity of casein micelles"] {{Webarchive|url=https://web.archive.org/web/20120313062736/http://www.prodinra.inra.fr/prodinra/pinra/data/2008/04/PROD2008990fa814_20080417115100287.pdf |date=2012-03-13}}, "Milchwissenschaft", 62(1):3</ref>
Heating this salt above 169 °C gives disodium pyrophosphate: :{{chem2|2 NaH2PO4 → Na2H2P2O7 + H2O}}
When heated at 550 °C, anhydrous trisodium trimetaphosphate is formed:<ref>{{cite book |doi=10.1002/9780470132340.ch26|chapter=Sodium Metaphosphates |year=1950 |last1=Bell |first1=R. N. |title=Inorganic Syntheses |pages=103–106 |volume=3}}</ref> :{{chem2|3 NaH2PO4 → Na3P3O9 + 3 H2O}}
==Uses== Phosphates are often used in foods and in water treatment. The pH of such formulations is adjusted by mixtures of various sodium phosphates, such as this salt.<ref name=Ullmann/> It is added in animal feed for its nutritional value.<ref name=Ullmann/>
==References== {{reflist}}
{{Sodium compounds}} {{Phosphates}} {{Mineral supplements}}
Category:Phosphates Category:Sodium compounds Category:Edible thickening agents