Specification :

Sodium tripolyphosphate is produced by heating a stoichiometric mixture of disodium phosphate, Na2HPO4, and monosodium phosphate, NaH2PO4, under carefully controlled conditions.[ 2]

2 Na2HPO4 + NaH2PO4 ’ Na5P3O10 + 2 H2O
In this way, approximately 2 million tons are produced annually.

STPP is a colourless salt, which exists both in anhydrous form and as the hexahydrate. The anion can be described as the pentanionic chain [ O3POP( O) 2OPO3] 5-.[ 3] [ 4] Many related di-, tri-, and polyphosphates are known including the cyclic triphosphate P3O93-. It binds strongly to metal cations as both a bidentate and tridentate chelating agent