ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

(NH₄)₂HPO₃-H₃PO₃-H₂O System

M. Ebert and J. Grospietsch

Department of Inorganic Chemistry, Faculty of Natural Sciences, Charles University, Prague

Abstract: The system (NH₄)₂-HPO₃-H₃PO₃-H₂O was 1st studied in the solid phase by the soly. method at 25° and then in the liq. phase by the elec. cond. method at concns. of 0.05, 0.1, and 0.5M and temps. of 25, 35 and 45°. A soly. diagram was constructed. It was detd. that only the congruently sol. NH₄H₂PO₃ was formed. The part in the range 63.5-79.9 wt. % H₃PO₃ is missing because the equil. of the liq. and solid phases could not be attained even after several months standing at 25° or after cooling down to 3°. Anal. of the deviations of the elec. cond. from additivity shows that there are in the soln. in addn. to NH₄H₂PO₃, the following three unknown polyorthophosphites: NH₄H₅P₂O₆, NH₄H₈P₃O₉, and (NH₄)₂H₇P₃O₉. The formation of these polyorthophosphites increases with increasing concn., but the effect of temp. is almost nil. It was detd. that NH₄H₅P₂O₆ is the most stable at all concns. and temps. The stabilities of NH₄H₈P₃O₉ and (NH₄)₂H₇P₃O₉ are about the same except that at 0.5M and 45°, the stability of (NH₄₎₂H₇P₃O₉ is higher than that of NH₄H₈P₃O₉.

Full paper in Portable Document Format: 228a578.pdf (in Czech)

Chemical Papers 22 (8) 578–583 (1968)