Triphosphoric acid (also tripolyphosphoric acid), with formula H₅P₃O₁₀, is a condensed form of

phosphoric acid Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula . It is commonly encountered as an 85% aqueous solution, w ...

. In the family of

phosphoric acids Phosphoric may refer to: *Phosphoric acid *Phosphoric anhydride, see phosphorus pentoxide See also *Phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white ph ...

, it is the next polyphosphoric acid after

pyrophosphoric acid Pyrophosphoric acid, also known as diphosphoric acid, is the inorganic compound with the formula H4P2O7 or, more descriptively, HO)2P(O)sub>2O. Colorless and odorless, it is soluble in water, diethyl ether, and ethyl alcohol. The anhydrous acid c ...

, H₄P₂O₇, also called diphosphoric acid. Compounds such as ATP (

adenosine triphosphate Adenosine triphosphate (ATP) is an organic compound that provides energy to drive many processes in living cells, such as muscle contraction, nerve impulse propagation, condensate dissolution, and chemical synthesis. Found in all known forms o ...

) are

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides a ...

s 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 Sodium triphosphate (STP), also sodium tripolyphosphate (STPP), or tripolyphosphate (TPP),

, at 0 °C. Triphosporic acid is a pentaprotic acid, meaning that it can release five protons in basic enough conditions. Sources differ on the corresponding p''K''_a values: * 1.0; 2.2; 2.3; 5.7; 8.5 * 1.0; 2.2; 2.3; 3.7; 8.5 * small; small; 2.30; 6.50; 9.24

References

Phosphorus oxoacids Phosphorus(V) compounds {{Inorganic-compound-stub