... -21-4 Appearance: White crystal powder 1-Hydroxy Ethylidene-1,1-DiphosphonicAcid (HEDP)CAS No. 2809-21 ... max100.0maxpH (1% solution)2.0 max2.0 maxDensity (20°C)g/cm31.43-1.47-Fe ... 1-Hydroxy Ethylidene-1,1-Diphosphonic Acid; Hydroxyethylidene-1,1-diphosphonicacid(HEDP); 1-HYDROXYETHYLIDENEDIPHOSPHONIC ACID;Hydroxyethylidene Diphosphonic acid(HEDP); 1-hydroxy-1,1-Ethanediyl ester 1-Hydroxy Ethylidene-1,1 ...