Disodium phosphate

Disodium phosphate
IUPAC name Sodium hydrogen phosphate
Other names Disodium hydrogen orthophosphate Sodium hydrogen phosphate Sodium phosphate dibasic
Identifiers
CAS number	7558-79-4 Y,  10028-24-7 (dihydrate) 7782-85-6 (heptahydrate) 10039-32-4 (dodecahydrate)
ChemSpider	22625 Y
UNII	22ADO53M6F Y
EC number	231-448-7
ChEBI	CHEBI:34683 Y
ChEMBL	CHEMBL1060 Y
RTECS number	WC4500000
Jmol-3D images	Image 1
SMILES [Na+].[Na+].[O-]P([O-])([O-])=O
InChI InChI=1S/2Na.H3O4P/c;;1-5(2,3)4/h;;(H3,1,2,3,4)/q2*+1;/p-3 N Key: BNIILDVGGAEEIG-UHFFFAOYSA-K N InChI=1/2Na.H3O4P/c;;1-5(2,3)4/h;;(H3,1,2,3,4)/q2*+1;/p-3 Key: BNIILDVGGAEEIG-DFZHHIFOAK
Properties
Molecular formula	Na2HPO4
Molar mass	141.96 g/mol
Appearance	White crystalline solid
Density	0.5–1.2 g/cm3
Melting point	250 ºC decomp.
Solubility in water	7.7 g/100 ml (20 ºC)
Hazards
MSDS	ICSC 1129
EU Index	Not listed
Main hazards	Irritant
NFPA 704	0 1 0
Flash point	Non-flammable
Related compounds
Other anions	sodium phosphite
Other cations	Dipotassium phosphate Diammonium phosphate
Related compounds	Monosodium phosphate Trisodium phosphate
N phosphate (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Disodium hydrogen phosphate (Na₂HPO₄) is a sodium salt of phosphoric acid. It is a white powder that is highly hygroscopic and water soluble.^[1] It is therefore used commercially as an anti-caking additive in powdered products. It is also known as disodium hydrogen orthophosphate, sodium hydrogen phosphate or sodium phosphate dibasic. It is commercially available in both the hydrated and anhydrous forms.^[2] pH of disodium hydrogen phosphate water solution is between 8.0 and 11.0.

Preparation

It may be formed by reaction of stoichiometric quantities of sodium hydroxide and phosphoric acid:

2 NaOH + H₃PO₄ → Na₂HPO₄ + 2 H₂O

Other uses

• Disodium phosphate is used in Cream of Wheat to quicken cook time, as described on the ingredients panel of the product package.
• Disodium phosphate is used in conjunction with trisodium phosphate in many steam-boiler applications. It supplies the inventory of free phosphates to retard calcium scale formation.
• Monobasic and dibasic sodium phosphate is used as a saline laxative to treat constipation or to clean the bowel before a colonoscopy.

References

1. ^ Physical data (pdf)
2. ^ MSDS