Monosodium phosphate

Monosodium phosphate

Names
IUPAC name Sodium dihydrogen phosphate
Other names anhydrous monobasic sodium phosphate sodium dihydrogen phosphate
Identifiers
CAS Number	7558-80-7 Y
ChEBI	CHEBI:37585 Y
ChEMBL	ChEMBL1368 Y
ChemSpider	22626 Y
Jmol interactive 3D	Image
PubChem	24204
UNII	KH7I04HPUU N
InChI InChI=1S/Na.H3O4P/c;1-5(2,3)4/h;(H3,1,2,3,4)/q+1;/p-1 Y Key: AJPJDKMHJJGVTQ-UHFFFAOYSA-M Y
SMILES [Na+].[O-]P(=O)(O)O
Properties
Chemical formula	NaH2PO4
Molar mass	119.98 g/mol
Appearance	White powder or crystals
Density	2.36 g/cm3 (anhydrous)
Solubility in water	59.90 g/100 mL (0°C)
Hazards
NFPA 704	0 1 0
Flash point	Non-flammable
Related compounds
Other cations	Monopotassium phosphate Monoammonium phosphate
Related compounds	Disodium phosphate Trisodium phosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
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

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

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

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

Notes