Ammonium dihydrogenphosphate with Sodium dihydrogenphosphate, Sodium nitrate and Water (IUPAC SDS Volume 66)
Evaluator
Jitka Eysseltová Department of Inorganic Chemistry, Charles University
Evaluation
8.2. NH4+, Na+|| H2PO4-, NO3- - H2O

In contrast to other multicomponent systems involving ammonium dihydrogenphosphate, the NH4+, Na+ || H2PO4-, NO3- - H2O system has been studied in detail. Shpunt1-3 determined solubility isotherms of this system at 253 K, 258 K, 263 K, 273 K, 293 K and 303 K and also made a polythermal investigation of the stable diagonal NH4H2PO4 - NaNO3 - H2O system. Figure 21, Fig. 22, Fig. 23, and Fig. 24 show a comparison of some of these solubility values with those reported earlier by Shpunt7 as well as results reported by other investigators who studied the boundary ternary systems,4,5,7,8 (see pp 1343, 1351). It is obvious that the agreement is not very good even with results reported by a given author. Consequently, nothing definitive can be said about the shape of the respective phase diagram at this time.

Figures
Solubility graph
FIG. 21. The solid phases are NaH2PO4·2H2O and NaNO3.
Solubility graph
FIG. 22. The solid phases are NaH2PO4·2H2O and NH4H2PO4.
Solubility graph
FIG. 23. The solid phases are NH4H2PO4 and NH4NO3.
Solubility graph
FIG. 24. The solid phases are NH4H2PO4 and NaNO3.
Sources:

1 Shpunt, S. Ya.; Zh. Prikl. Khim. 20, 685 (1947).
2 Shpunt, S. Ya.; Zh. Prikl. Khim. 30, 984 (1957).
3 Shpunt, S. Ya.; Zh. Prikl. Khim. 30, 1148 (1957).
4 Bergman, A. G.; Bochkarev, P. F.; Izv. Akad. Nauk USSR, Otd. Mat. Estestv. Nauk 237-266 (1938).
5 Bochkarev, P. F.; Tr. Vostoch. -Sibir. Gosud. Inst. 3-22 (1935).
6 Shpunt, S. Ya.; Zh. Prikl. Khim. 13, 9 (1940).
7 Bergman, A. G.; Bochkarev, P. F.; Zh. Prikl. Khim. 10, 1531-1560 (1937).
8 Kol'ba, V. I.; Zhikarev, M. I.; Sukhanov, L. P.; Zh. Neorg. Khim. 26, 828 (1981).
9 Iovi, A.; Haiduc, C.; Rev. Roum. Chim. 16, 1743 (1971).