DESCRIPTION

Sodium Polyphosphates, Glassy, occur as colorless or white, transparent platelets, granules, or powders. They belong to a class consisting of several amorphous, water-soluble polyphosphates composed of linear chains of metaphosphate units (NaPO₃) x for which × ≥ 2, terminated by Na₂PO₄–groups. They are usually identified by their Na₂O/P₂O₅ ratio or their phosphorus pentoxide (P₂O₅ ) content. The Na₂O/P₂O₅ ratios vary from about 1.5 for sodium tetrapolyphosphate, for which x = approximately 2 through about 1.1 for Graham's salt, commonly called sodium hexametaphosphate, for which x = 10 to 18; to about 1.0 for the higher molecular weight sodium polyphosphates, for which x = 20 to 100 or more. Glassy Sodium Polyphosphates are very soluble in water. The pH of their solutions varies from about 3.0 to 9.0.