IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

Glass Ball as Bullet Solubility System: Ammonium dihydrogenphosphate with Diammonium hydrogenphosphate, Urea 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) Urea; CH4N2O; [57-13-6]  NIST Chemistry WebBook for detail
   (4) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail
Original Measurements:
   Ivanov, D.G.; Grantscharov, I.N., God. Vissh. Khimikotekhnol. Inst. Sofiya 1970, 15, 159.

 Variables:

   Concentration = Temperature and composition in solutions with a NH3/H3PO4 ratio = 1.4 and 1.5.

 Prepared By:
   J. Eysseltová

 Experimental Remarks:
   Data for some sections through the solubility polytherms at constant total salt concentration, and isotherms at 0 ºC, 15 ºC and 30 ºC are given in graphical form. The authors also give the following equations expressing the dependence of total plant food on both temperature and the P2O5/N ratio.

          N + P2O5 = a + bT (P2O5/N) is constant                      [1]             The equilibrium solid phase is constant
          N + P2O5 = c + d(P2O5/N) (t is constant)                       [2]            
          N + P2O5 = a1 + b1(P2O5/N) + c1T + d1T(P2O5/N)        [3]        "
          N + P2O5 = e + f(P2O5/N) + gT(P2O5/N)h            [4]      "

Equation (3) is used when the NH/P2O5 ratio is 1.4; Eq. (4) is used when the ratio is 1.5.

Experimental Data:   (Notes on the Nomenclature)
  

Table 1. Constants for Eqs. (1) - (4) values of constants a,b
t/°CMass Fraction w1Mole Fraction1Comment(s)
0-50Mass ratio P2O5/N = 3.62mol ratio of NH3/H3PO4 = 1.4a = 32.10; b = 0.271
0-602.74mol ratio of NH3/H3PO4 = 1.4a = 31.23; b = 0.263
0-602.10mol ratio of NH3/H3PO4 = 1.4a = 30.30; b = 0.273
0-551.62mol ratio of NH3/H3PO4 = 1.4a = 29.68; b = 0.283
0-551.23mol ratio of NH3/H3PO4 = 1.4a = 29.43; b = 0.274
0-430.68mol ratio of NH3/H3PO4 = 1.4a = 28.80; b = 0.303
0-470.47mol ratio of NH3/H3PO4 = 1.4a = 26.76; b = 0.269
0-500.29mol ratio of NH3/H3PO4 = 1.4a = 24.27; b = 0.259
0-550.13mol ratio of NH3/H3PO4 = 1.4a = 21.77; b = 0.252
0-403.37mol ratio of NH3/H3PO4 = 1.5a = 34.73; b = 0.325
0-402.58mol ratio of NH3/H3PO4 = 1.5a = 33.59; b = 0.310
0-402.00mol ratio of NH3/H3PO4 = 1.5a = 33.06; b = 0.277
0-401.55mol ratio of NH3/H3PO4 = 1.5a = 32.46; b = 0.254
2.5-401.19mol ratio of NH3/H3PO4 = 1.5a = 32.29; b = 0.199
0.250.66mol ratio of NH3/H3PO4 = 1.5a = 28.69; b = 0.289
0-350.45mol ratio of NH3/H3PO4 = 1.5a = 26.08; b = 0.284
0-400.28mol ratio of NH3/H3PO4 = 1.5a = 23.65; b = 0.275
0-420.13mol ratio of NH3/H3PO4 = 1.5a = 21.33; b = 0.264
Table 2. Constants for Eqs. (1) - (4) values of constants c,d
t/°CMole Fraction1Mass RatioComment(s)
0-50mol ratio of NH3/H3PO4 = 1.4Interval of the P2O5/N ratio = 1.23 - 3.62c = 28.14; d = 1.03
0-60mol ratio of NH3/H3PO4 = 1.41.23 - 3.62c = 30.95; d = 0.96
0-60mol ratio of NH3/H3PO4 = 1.41.23 - 3.62c = 33.40; d = 1.00
0-55mol ratio of NH3/H3PO4 = 1.41.23 - 3.62c = 36.13; d = 1.05
0-55mol ratio of NH3/H3PO4 = 1.41.23 - 3.62c = 38.71; d = 1.10
0-43mol ratio of NH3/H3PO4 = 1.40.10 - 0.97c = 22.19; d = 14.50
0-47mol ratio of NH3/H3PO4 = 1.40.10 - 0.90c = 24.75; d = 14.51
0-50mol ratio of NH3/H3PO4 = 1.40.10 - 0.84c = 27.30; d = 14.64
0-55mol ratio of NH3/H3PO4 = 1.51.18 - 3.37c = 30.85; d = 1.11
0-40mol ratio of NH3/H3PO4 = 1.50.98 - 3.37c = 32.32; d = 1.65
0-40mol ratio of NH3/H3PO4 = 1.50.80 - 3.37c = 34.17; d = 2.12
0-40mol ratio of NH3/H3PO4 = 1.50.68 - 3.37c = 35.33; d = 2.82
0-40mol ratio of NH3/H3PO4 = 1.50.10 - 0.90c = 19.53; d = 13.76
2.5-40mol ratio of NH3/H3PO4 = 1.50.10 - 0.90c = 22.09; d = 14.33
0.25mol ratio of NH3/H3PO4 = 1.50.10 - 0.77c = 24.52; d = 15.51
Table 3. Constants for Eqs. (1) - (4) values of constants a - h
Chemical1Mole Fraction1Comment(s)
Equilibrium solid phase NH4H2PO4mol ratio of NH3/H3PO4 = 1.4a1 = 28.14; b1 = 1.03; c1 = 0.282; d1 = 0.0044
CO(NH2)2mol ratio of NH3/H3PO4 = 1.4a1= 19.86; b1 = 13.84; c1 = 0.238; d1 = 0.086
Equilibrium solid phase NH4H2PO4mol ratio of NH3/H3PO4 = 1.5e = 30.82; f = 1.121; g = 0.196; h = 0.456
CO(NH2)2mol ratio of NH3/H3PO4 = 1.5e = 19.37; f = 14.48; g = 0.298; h = 0.065
 Method/Apparatus/Procedure:
   All experimental details have been described earlier.1

 Source and Purity of Materials:
   Reagent grade urea, NH4H2PO4 and (NH4)2HPO4 were recrystallized before being used.

 Estimated Errors:
   Solubility: Equations (1) and (2) describe the data with a relative error of ± 0.5-2%; for Eqs. (3) and (4) the error is ± 2.5% and ± 3.5%, respectively.

 References:
   1Ivanov, D.G.; Grantscharov, I.N. God. Vissh. Khimikotekhnol. Inst., Sofiya 1966, 13, 165.