Triphosphoric acid (also tripolyphosphoric acid), with formula H₅P₃O₁₀, is a condensed form of phosphoric acid. In the family of phosphoric acids, it is the next polyphosphoric acid after pyrophosphoric acid, H₄P₂O₇, also called diphosphoric acid.

Triphosphoric acid

Names
IUPAC name Diphosphono hydrogenphosphate
Systematic IUPAC name Triphosphoric acid Tripolyphosphoric acid
Other names Diphosphonophosphoric acid Phosphono trihydrogenpyrophosphate Phosphonopyrophosphoric acid
Identifiers
CAS Number	10380-08-2 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:39949 N
ChemSpider	958 N
ECHA InfoCard	100.030.752
EC Number	233-840-3
KEGG	C00404 N
PubChem CID	983
UNII	NU43IAG5BC Y
CompTox Dashboard (EPA)	DTXSID7047483
InChI InChI=1S/H5O10P3/c1-11(2,3)9-13(7,8)10-12(4,5)6/h(H,7,8)(H2,1,2,3)(H2,4,5,6) N Key: UNXRWKVEANCORM-UHFFFAOYSA-N N
SMILES OP(=O)(O)OP(=O)(O)OP(=O)(O)O
Properties
Chemical formula	H5P3O10
Molar mass	257.95 g/mol
Acidity (pKa)	See body
Conjugate base	Triphosphate
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Corrosive (C)
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

Compounds such as ATP (adenosine triphosphate) are esters of triphosphoric acid.

Triphosphoric acid has not been obtained in crystalline form. The equilibrium mixture with an overall composition corresponding to H₅P₃O₁₀ contains about 20% of triphosphoric acid. A solution of the pure species can be obtained by ion exchange of the sodium salt, sodium triphosphate, at 0 °C.^[1]

Triphosporic acid is a pentaprotic acid, meaning that it can release five protons in basic enough conditions. Sources differ on the corresponding pK_a values:

• 1.0; 2.2; 2.3; 5.7; 8.5^[1]
• 1.0; 2.2; 2.3; 3.7; 8.5^[2]
• small; small; 2.30; 6.50; 9.24^{[citation needed]}