IUPAC-NIST Solubility Database
NIST Standard Reference Database 106

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 Solubility System: Ammonium dihydrogenphosphate with Diammonium hydrogenphosphate, Urea, Potassium chloride and Water

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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 chloride; KCl; [7747-40-7]  NIST Chemistry WebBook for detail
   (4) Urea; CH4N2O; [57-13-6]  NIST Chemistry WebBook for detail
   (5) Water; H2O; [7732-18-5]  NIST Chemistry WebBook for detail

Original Measurements:
   Slack, A.V.; Hatfield, J.D.; Shaffer, H.B.; Driskell, J.C., J. Agr. Food Chem. 1959, 7, 404.

Variables:

   Concentration = Temperature and composition.

Prepared By:
   J. Eysseltová

Experimental Remarks:

   Remarks: Solubility isotherms at 0 ºC are given only graphically as contours of constant plant nutrient content in the saturated solutions with the nutrient ratios as the variables. Numerically, the data are expressed by Eq. [1] y = a + bt     [1] where y is the percent total plant nutrient (% N + %P₂O₅ + %K₂O) in the saturated solution at temperature t (ºC), and a and b are constants for each combination of nutrient ratio and ammoniation level. These constants are given in the table below.

Experimental Data:   (Notes on the Nomenclature)
(Please see footnotes following the table(s).)   

Mol ratio NH₃/H₃PO₄

Chemical1	Mole Fraction1	Comment(s)
Nutrient ratio (1-3-0) (a)	1.5 Mol ratio	Constants a = 34.6 (b), b = 0.342
Nutrient ratio (1-3-0) (a)	1.6	Constants a = 36.9 (c), b =0.141
Nutrient ratio (1-3-0) (a)	1.7	Constants a = 34.1 (c), b = 0.119
Nutrient ratio (1-2-0) (a)	1.5	Constants a = 35.8 (b), b = 0.244
Nutrient ratio (1-2-0) (a)	1.6	Constants a = 34.7 (c), b = 0.123
Nutrient ratio (1-2-0) (a)	1.7	Constants a = 32.1 (c), b = 0.119
Nutrient ratio (1-1-0) (a)	1.5	Constants a = 32.7 (d), b = 0.241
Nutrient ratio (1-1-0) (a)	1.6	Constants a = 31.8 (e), b = 0.082
Nutrient ratio (1-1-0) (a)	1.7	Constants a = 29.1 (c), b = 0.119
Nutrient ratio (1-1-0) (a)	1.5	Constants a = 34.6 (f), b = 0.065
Nutrient ratio (2-1-0) (a)	1.5	Constants a = 26.2 (g), b = 0.283
Nutrient ratio (2-1-0) (a)	1.6	Constants a = 26.1 (h), b = 0.281
Nutrient ratio (2-1-0) (a)	1.7	Constants a = 26.1 (i), b = 0.262
Nutrient ratio (2-1-0) (a)	1.6	Constants a = 30.3 (kj), b = 0.071
Nutrient ratio (2-1-0) (a)	1.6	Constants a = 28.6 (k), b = 0.070
Nutrient ratio (1-3-1) (a)	1.5	Constants a = 31.2 (b), b = 0.233
Nutrient ratio (1-3-1) (a)	1.6	Constants a = 34.9 (c), b = 0.133
Nutrient ratio (1-3-1) (a)	1.7	Constants a = 32.1 (c), b = 0.115
Nutrient ratio (1-2-1) (a)	1.5	Constants a = 28.2 (b), b = 0.245
Nutrient ratio (1-2-1) (a)	1.6	Constants a = 32.5 (m), b = 0.130
Nutrient ratio (1-2-1) (a)	1.7 Mol ratio	Constants a = 31.3 (c), b = 0.117
Nutrient ratio (1-1-1) (a) (m)	1.5	Constants a = 25.9, b = 0.156
Nutrient ratio (1-1-1) (a) (m)	1.6 Mol ratio	Constants a = 27.6, b = 0.155
Nutrient ratio (1-1-1) (a) (m)	1.7	Constants a = 27.9, b = 0.131
Nutrient ratio (2-1-2) (a) (m)	1.5 Mol ratio	Constants a = 25.2, b = 0.118
Nutrient ratio (2-1-2) (a) (m)	1.6	Constants a = 25.2, b = 0.121
Nutrient ratio (2-1-2) (a) (m)	1.7	Constants a = 25.2, b = 0.118
Nutrient ratio (1-3-3) (a) (m)	1.5	Constants a = 24.7, b = 0.138
Nutrient ratio (1-3-3) (a) (m)	1.6	Constants a = 24.8, b = 0.135
Nutrient ratio (1-3-3) (a) (m)	1.7	Constants a = 24.5, b = 0.139
Nutrient ratio (1-2-3) (a) (m)	1.5	Constants a = 22.7, b = 0.124
Nutrient ratio (1-2-3) (a) (m)	1.6	Constants a = 22.6, b = 0.134
Nutrient ratio (1-2-3) (a) (m)	1.7	Constants a = 22.6, b = 0.129
Nutrient ratio (1-1-3) (a) (m)	1.5	Constants a = 20.0, b = 0.121
Nutrient ratio (1-1-3) (a) (m)	1.6	Constants a = 19.9, b = 0.125
Nutrient ratio (1-1-3) (a) (m)	1.7	Constants a = 20.0, b = 0.121
Nutrient ratio (2-1-6) (a) (m)	1.5	Constants a = 18.3, b = 0.121
Nutrient ratio (2-1-6) (a) (m)	1.6	Constants a = 18.5, b = 0.117
Nutrient ratio (2-1-6) (a) (m)	1.7	Constants a = 18.5, b = 0.117

Notes:
   Table 1  ^a  The nutrient ratio is the weight ratio N:P₂O₅·K₂O. Symbol solid phase.
   Table 1  ^b  NH₄H₂PO₄
   Table 1  ^c  (NH₄)₂HPO₄
   Table 1  ^d  CO(NH₂)₂ (t<10.8 °C)
   Table 1  ^e  (NH₄)₂HPO₄ (t>–1.5 °C), urea crystallized below –1.5 °C.
   Table 1  ^f  (NH₄)₂HPO₄ (t>10.8 °C)
   Table 1  ^g  CO(NH₂)₂
   Table 1  ^h  CO(NH₂)₂ (t>20.0 °C)
   Table 1  ⁱ  CO(NH₂)₂(t<12.9 °C)
   Table 1  ^j  (NH₄)₂HPO₄ (t>20.0 °C)
   Table 1  ^k  (NH₄)₂HPO₄ (t>12.9 °C)
   Table 1  ^m  KCl

Method/Apparatus/Procedure:
   The solubility was determined by a polythermal method. The solutions were cooled until crystallization occurred and then warmed (2 °C per hour) with continuous stirring until the last crystals disappeared. The crystalline phases were identified petrographically.

Source and Purity of Materials:
   All the salts used were reagent grade. The water was deionized.

Estimated Errors:
   Solubility: The standard deviation of equation [1] from the measured values was 0.12 % in plant nutrient.

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Last updated: February 18, 2015 (Created: August 17, 2007)