Tetrasodium pyrophosphate

Tetrasodium pyrophosphate

Names
IUPAC name Tetrasodium diphosphate
Other names Pyrophosphate, Sodium pyrophosphate, Tetrasodium pyrophosphate (anhydrous), TSPP[1]
Identifiers
CAS Number	7722-88-5 Y 13472-36-1 (decahydrate) Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:71240
ECHA InfoCard	100.028.880
EC Number	231-767-1
E number	E450(iii) (thickeners, ...)
PubChem CID	24403
RTECS number	UX7350000
UNII	O352864B8Z Y IY3DKB96QW (decahydrate) Y
CompTox Dashboard (EPA)	DTXSID9042465
InChI InChI=1S/4Na.H4O7P2/c;;;;1-8(2,3)7-9(4,5)6/h;;;;(H2,1,2,3)(H2,4,5, 6)/q4*+1;/p-4
SMILES [O-]P(=O)([O-])OP(=O)([O-])[O-].[Na+].[Na+].[Na+].[Na+]
Properties
Chemical formula	Na4O7P2
Molar mass	265.900 g·mol−1
Appearance	Colorless or white crystals[2]
Odor	odorless
Density	2.534 g/cm3
Melting point	988 °C (1,810 °F; 1,261 K) (anhydrous) 79.5 °C (decahydrate)
Boiling point	decomposes
Solubility in water	2.61 g/100 mL (0 °C) 6.7 g/100 mL (25 °C) 42.2 g/100 mL (100 °C)
Solubility	insoluble in ammonia, alcohol
Refractive index (nD)	1.425
Structure
Crystal structure	monoclinic (decahydrate)
Thermochemistry
Heat capacity (C)	241 J/mol K
Std molar entropy (S⦵298)	270 J/mol K
Std enthalpy of formation (ΔfH⦵298)	-3166 kJ/mol
Gibbs free energy (ΔfG⦵)	-3001 kJ/mol
Hazards
Flash point	Non-flammable
NIOSH (US health exposure limits):
PEL (Permissible)	none[2]
REL (Recommended)	TWA 5 mg/m3[2]
IDLH (Immediate danger)	N.D.[2]
Related compounds
Other anions	Trisodium phosphate Pentasodium triphosphate Sodium hexametaphosphate
Other cations	Tetrapotassium pyrophosphate
Related compounds	Disodium pyrophosphate
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

Tetrasodium pyrophosphate, also called sodium pyrophosphate, tetrasodium phosphate or TSPP, is an inorganic compound with the formula Na₄P₂O₇. As a salt, it is a white, water-soluble solid. It is composed of pyrophosphate anion and sodium ions. Toxicity is approximately twice that of table salt when ingested orally.^[3] Also known is the decahydrate Na₄P₂O₇ · 10(H₂O).^[4]