Monosodium phosphate

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Monosodium phosphate
Monosodium phosphate.png
Ball-and-stick model of the dihydrogenphosphate anion
Dihydrogenfosforečnan sodný.JPG
Names
IUPAC name
Sodium dihydrogen phosphate
Other names
anhydrous monobasic sodium phosphate
sodium dihydrogen phosphate
Identifiers
7558-80-7 YesY
ChEBI CHEBI:37585 YesY
ChEMBL ChEMBL1368 YesY
ChemSpider 22626 YesY
Jmol-3D images Image
PubChem 24204
UNII KH7I04HPUU N
Properties
NaH2PO4
Molar mass 119.98 g/mol
Appearance White powder or crystals
Density 2.36 g/cm3 (anhydrous)
59.9 g/100 mL (0°C)
Hazards
EU Index Not listed
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point Non-flammable
Related compounds
Other cations
Monopotassium phosphate
Monoammonium phosphate
Related compounds
Disodium phosphate
Trisodium phosphate
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Monosodium phosphate (MSP), also known as anhydrous monobasic sodium phosphate and sodium dihydrogen phosphate, is an inorganic compound of sodium with dihydrogen phosphate (H2PO4) anion. One of many sodium phosphates, it is a common industrial chemical. It exists as an anhydrous salt, as well as mono- and dihydrates.[1]

Production and reactions[edit]

The salt is obtained by partial neutralization of phosphoric acid. The pKa of monosodium phosphate is 6.8-7.2 (depending on the physicochemical characteristics during pKa determination).[2]

Heating this salt above 169 °C gives the corresponding sodium acid pyrophosphate:

2 NaH2PO4 → Na2H2P2O7 + H2O

Uses[edit]

Phosphates are often used in foods and in water treatment. The pH of such formulations is generally adjusted by mixtures of various sodium phosphates, such as this salt.[1] The sodium chloride equivalent value, or E-Value, is 0.49. It is soluble in 4.5 parts water.

Food additive[edit]

It is added in animal feed, toothpaste, and evaporated milk. It is used as an thickening agent and emulsifier.

Notes[edit]

  1. ^ a b Klaus Schrödter, Gerhard Bettermann, Thomas Staffel, Friedrich Wahl, Thomas Klein, Thomas Hofmann "Phosphoric Acid and Phosphates" in Ullmann’s Encyclopedia of Industrial Chemistry 2008, Wiley-VCH, Weinheim. doi:10.1002/14356007.a19_465.pub3
  2. ^ Salaun, F.: "Influence of mineral environment on the buffering capacity of casein micelles", "Milchwissenschaft", 62(1):3