Compilation - Ammonium dihydrogenphosphate with Diammonium hydrogenphosphate, Urea and Water (IUPAC SDS Volume 66)
SDS Volume (2986)
Volume 66. Ammonium Phosphates, p None
Original Measurements
Ivanov, D. G.; Grantscharov, I. N.; God. Vissh. Khimikotekhnol. Inst. Sofiya 1966, 13, 165.
Variables:
Temperature and composition in solutions with a NH3/H3PO4 ratio = 1.8.
Prepared by:
Method/Apparatus/Procedure:
A visual polythermic method was used. The apparatus consisted of two thermostated reaction vessels, the contents of which were stirred vigorously. The appearance/disappearance of the last crystal was observed with a stereomicroscope. The composition of the equilibrium solid phases was determined analytically. Nitrogen (total and ammoniacal) was determined by the Kjeldahl method. Phosphate ions were precipitated as $\ce{NH4MgPO4.6H2O}$ and the excess $\ce{Mg}$ was titrated complexometrically using Eriochrome black T as indicator.
Source and Purity of Materials:
- Reagent grade urea, $\ce{NH4H2PO4}$ and $\ce{(NH4)2HPO4}$ were recrystallized before being used.
Estimated Errors:
Ambient temperature: The reproducibility of the crystallization temperature was within 0.3 K. For the correlations see EXPERIMENTAL VALUES.
Components:
- Ammonium dihydrogenphosphate, $\ce{ NH4H2PO4 }$; [7722-76-1] NIST WebBook
- Diammonium hydrogenphosphate, $\ce{ (NH4)2HPO4 }$; [7783-28-0] NIST WebBook
- Urea, $\ce{ CH4N2O }$; [57-13-6] NIST WebBook
- Water, $\ce{ H2O }$; [7732-18-5] NIST WebBook
Experimental Data
Part 3. Comments and Additional Data:
The authors presented the following equations relating total plant food to temperature and to the P2O5/N ratio.
N + P2O5 = a + b(T-273.16) P2O5/N is constant[1] the equilibrium solid phase is constant
N + P2O5 = c + d(P2O5/N) T is constant[2]
N + P2O5 = e + f(P2O5/N) + g(T-273.16)
(P2O5/N)h[3]
The values of the constants are summarized in the Table below.
Comment: The equations describe the experimental data with a relative error of ±0.5%.
Part 2. The compiler has recalculated the data in Part 1 to give the following concentration values.
| 100w1 | 100w2 | 100w3 | 100w4 | m1 (mol/kg) | m2 (mol/kg) | m3 (mol/kg) |
|---|---|---|---|---|---|---|
| 50.43 | 10.33 | 2.27 | 36.98 | 22.71 | 2.11 | 0.53 |
| 56.74 | 5.13 | 1.16 | 36.98 | 25.54 | 1.05 | 0.27 |
| 63.06 | 0.00 | 0.00 | 36.94 | 28.43 | 0.00 | 0.00 |
| 48.84 | 9.98 | 2.21 | 38.97 | 20.87 | 1.94 | 0.49 |
| 54.93 | 5.03 | 1.08 | 38.96 | 23.48 | 0.98 | 0.24 |
| 61.13 | 0.00 | 0.00 | 38.87 | 26.19 | 0.00 | 0.00 |
| 41.31 | 14.33 | 3.50 | 40.86 | 16.83 | 2.66 | 0.74 |
| 47.23 | 9.64 | 2.15 | 40.97 | 19.19 | 1.78 | 0.46 |
| 53.13 | 4.78 | 1.10 | 40.99 | 21.58 | 0.88 | 0.23 |
| 58.99 | 0.00 | 0.00 | 41.01 | 23.95 | 0.00 | 0.00 |
| 34.23 | 18.68 | 4.11 | 42.97 | 13.26 | 3.29 | 0.83 |
| 39.94 | 13.98 | 3.12 | 42.96 | 15.48 | 2.46 | 0.63 |
| 45.65 | 9.30 | 2.10 | 42.96 | 17.69 | 1.64 | 0.42 |
| 51.33 | 4.69 | 1.02 | 42.96 | 19.89 | 0.83 | 0.21 |
| 57.06 | 0.00 | 0.00 | 42.94 | 22.12 | 0.00 | 0.00 |
| 0.00 | 45.04 | 9.95 | 45.01 | 0.00 | 7.58 | 1.92 |
| 5.51 | 40.53 | 8.95 | 45.01 | 2.04 | 6.82 | 1.73 |
| 11.00 | 35.99 | 7.99 | 45.01 | 4.07 | 6.06 | 1.54 |
| 16.52 | 31.48 | 7.00 | 45.01 | 6.11 | 5.30 | 0.35 |
| 22.01 | 27.04 | 5.95 | 45.00 | 8.14 | 4.55 | 1.15 |
| 27.52 | 22.53 | 4.96 | 44.99 | 10.18 | 3.79 | 0.96 |
| 33.03 | 18.02 | 3.96 | 44.99 | 12.23 | 3.03 | 0.77 |
| 38.52 | 13.48 | 3.00 | 44.99 | 14.26 | 2.27 | 0.58 |
| 44.04 | 8.95 | 2.04 | 44.97 | 16.30 | 1.51 | 0.39 |
| 49.53 | 4.53 | 0.96 | 44.98 | 18.33 | 0.76 | 0.19 |
| 54.91 | 0.00 | 0.00 | 45.09 | 20.28 | 0.00 | 0.00 |
| 0.00 | 42.57 | 9.41 | 48.02 | 0.00 | 6.71 | 1.70 |
| 5.21 | 38.31 | 8.47 | 48.01 | 1.81 | 6.04 | 1.53 |
| 10.40 | 34.04 | 7.54 | 48.02 | 3.61 | 5.37 | 1.36 |
| 15.62 | 29.62 | 6.74 | 48.03 | 5.41 | 4.67 | 1.22 |
| 20.81 | 25.51 | 5.66 | 48.02 | 7.21 | 4.02 | 1.03 |
| 26.02 | 21.25 | 4.73 | 48.00 | 9.02 | 3.35 | 0.86 |
| 31.21 | 17.08 | 3.71 | 48.00 | 10.83 | 2.69 | 0.67 |
| 36.42 | 12.79 | 2.81 | 47.98 | 12.64 | 2.02 | 0.51 |
| 41.63 | 8.53 | 1.87 | 47.96 | 14.45 | 1.35 | 0.34 |
| 46.83 | 4.26 | 0.94 | 47.97 | 16.25 | 0.67 | 0.17 |
| 52.12 | 0.00 | 0.00 | 47.88 | 18.13 | 0.00 | 0.00 |
| 0.00 | 40.97 | 9.01 | 50.03 | 0.00 | 6.20 | 1.57 |
| 5.00 | 36.85 | 8.13 | 50.01 | 1.66 | 5.58 | 1.41 |
| 10.0 | 32.76 | 7.23 | 50.02 | 3.33 | 4.96 | 1.26 |
| 15.02 | 28.67 | 6.32 | 50.0 | 5.00 | 4.34 | 1.10 |
| 20.01 | 24.58 | 5.41 | 50.0 | 6.66 | 3.72 | 0.94 |
| 25.01 | 20.48 | 4.50 | 50.0 | 8.33 | 3.10 | 0.78 |
| 30.01 | 16.39 | 3.60 | 50.0 | 9.99 | 2.48 | 0.63 |
| 35.03 | 12.30 | 2.69 | 49.99 | 11.67 | 1.86 | 0.47 |
| 40.03 | 8.19 | 1.81 | 49.97 | 13.34 | 1.24 | 0.32 |
| 45.02 | 4.09 | 0.91 | 49.98 | 15.00 | 0.62 | 0.16 |
| 49.98 | 0.00 | 0.00 | 50.02 | 16.64 | 0.00 | 0.00 |
| 0.00 | 39.34 | 8.64 | 52.02 | 0.00 | 5.73 | 1.44 |
| 4.80 | 35.40 | 7.80 | 52.00 | 1.54 | 5.15 | 1.30 |
| 9.61 | 31.39 | 7.00 | 52.01 | 3.08 | 4.57 | 1.17 |
| 14.41 | 27.46 | 6.12 | 52.00 | 4.62 | 4.00 | 1.02 |
| 19.22 | 23.54 | 5.24 | 52.00 | 6.15 | 3.43 | 0.88 |
| 24.02 | 19.62 | 4.36 | 51.99 | 7.69 | 2.86 | 0.73 |
| 28.83 | 15.70 | 3.48 | 51.99 | 9.23 | 2.29 | 0.58 |
| 33.63 | 11.76 | 2.64 | 51.97 | 10.78 | 1.71 | 0.44 |
| 38.44 | 7.84 | 1.76 | 51.96 | 12.32 | 1.14 | 0.29 |
| 43.22 | 3.92 | 0.88 | 51.98 | 13.85 | 0.57 | 0.15 |
| 48.05 | 0.00 | 0.00 | 51.95 | 15.40 | 0.00 | 0.00 |
| 0.00 | 36.91 | 8.12 | 54.97 | 0.00 | 5.08 | 1.28 |
| 4.50 | 33.14 | 7.38 | 54.97 | 1.36 | 4.57 | 1.17 |
| 9.01 | 29.49 | 6.53 | 54.97 | 2.73 | 4.06 | 1.03 |
| 13.51 | 25.82 | 5.71 | 54.96 | 4.09 | 3.56 | 0.90 |
| 18.02 | 22.17 | 4.85 | 54.96 | 5.46 | 3.05 | 0.77 |
| 22.54 | 18.42 | 4.08 | 54.95 | 6.83 | 2.54 | 0.65 |
| 27.05 | 14.75 | 3.26 | 54.94 | 8.20 | 2.03 | 0.52 |
| 31.55 | 11.09 | 2.41 | 54.94 | 9.56 | 1.53 | 0.38 |
| 36.06 | 7.72 | 0.99 | 55.23 | 10.87 | 1.06 | 0.16 |
| 40.56 | 3.67 | 0.82 | 54.95 | 12.29 | 0.51 | 0.13 |
| 45.05 | 0.00 | 0.00 | 54.96 | 13.65 | 0.00 | 0.00 |
| 0.00 | 35.23 | 7.77 | 57.00 | 0.00 | 4.68 | 1.18 |
| 4.31 | 31.65 | 7.03 | 57.01 | 1.26 | 4.20 | 1.07 |
| 8.60 | 28.15 | 6.23 | 57.01 | 2.51 | 3.74 | 0.95 |
| 13.99 | 24.65 | 5.44 | 55.92 | 4.16 | 3.34 | 0.85 |
| 34.43 | 7.08 | 1.53 | 56.96 | 10.06 | 0.94 | 0.23 |
| 38.74 | 3.50 | 0.79 | 56.97 | 11.32 | 0.47 | 0.12 |
(a) This is a number characterizing the respective section. It is close to, but not identical with the total salt content of the system.
(b) This is the temperature of crystallization.
