IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

Glass Ball as Bullet Solubility System: Ammonium dihydrogenphosphate with Diammonium hydrogenphosphate, Potassium dihydrogenphosphate and Water
Components:
   (1) Ammonium dihydrogenphosphate; NH4H2PO4; [7722-76-1]  NIST Chemistry WebBook for detail
   (2) Diammonium hydrogenphosphate; (NH4)2HPO4; [7783-28-0]  NIST Chemistry WebBook for detail
   (3) Potassium dihydrogenphosphate; KH2PO4; [7778-77-0]  NIST Chemistry WebBook for detail
   (4) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail
Original Measurements:
   Vogel, L.; Figurski, G.; Vohland, P., Z. Chem. 1963, 23, 331.

 Variables:

   Concentration = Composition and temperature.

 Prepared By:
   J. Eysseltová

 Experimental Remarks:
   Remarks: The solubilities are presented in graphical form only. The data can be represented by the following equation: ln x = A + B/T + C lnT. Where x is the mol fraction of the salt in the saturated solution. The values of the constants are given below:
Salt component A B/K C Median error of smoothing (x)
NH4H2PO4 36.422 -3370.284 -4.901 0.156
(NH4)2HPO4 -31.639 697.129 4.718 0.072
KH2PO4 -4.810 -1510.549 1.128 0.094


 Experimental Data:   (Notes on the Nomenclature)
  
Salt component | Constants: A, B/K, C | Median error of smoothing (x)
Chemical1Comment(s)
NH4H2PO4A = 36.422; B/K = -3370.284; C = -4.901; median error of smoothing = 0.156
(NH4)2HPO4A = -31.639; B/K = 697.129; C = 4.718; median error of smoothing = 0.072
KH2PO4A = -4.810; B/K = -1510.549; C = 1.128; median error of smoothing = 0.094
 Method/Apparatus/Procedure:
   The method and apparatus have been described previously.1 However, plastic stoppers with glass caps were used instead of sealing the vessels.

 Source and Purity of Materials:
   No information is given.

 Estimated Errors:
   Solubility: The precision of the weights was ± 0.0001 g.
   Temperature: The temperature was accurate to within ± 0.05 K.

 References:
   1H. Schuberth, Abhandlung der Deutschen Akademie der Wissenschaften zu Berlin, Klasse fur Chemie, Geologie u. Biologie, Jg. Nr. 3 , p.40 (1960).