Monosodium phosphate

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Monosodium phosphate
Monosodium phosphate.png
Ball-and-stick model of the dihydrogenphosphate anion
Identifiers
CAS number 7558-80-7 YesY
PubChem 24204
ChemSpider 22626 YesY
ChEBI CHEBI:37585 YesY
ChEMBL CHEMBL1368 YesY
Jmol-3D images Image 1
Properties
Molecular formula NaH2PO4
Molar mass 119.98 g/mol
Appearance White powder or crystals
Density 2.36 g/cm3 (anhydrous)
Solubility in water 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 are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Monosodium phosphate (NaH2PO4), 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.

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