Phase Diagram for the System Ammonium Oxalate + Hydrogen Peroxide + Water at 283.15 K and 293.15 K

Abstract

The solubility of the ternary system (NH 4 ) 2 C 2 O 4 + H 2 O 2 + H 2 O was determined experimentally at 283.15 K and 293.15 K, and the phase diagrams for the system were constructed. In addition, the density of the saturated aqueous solution was measured. The experimental results showed that, at 283.15 K and 293.15 K, two solid phases were formed in the ternary (NH 4 ) 2 C 2 O 4 + H 2 O 2 + H 2 O system which correspond to (NH 4 ) 2 C 2 O 4 ‚H 2 O and (NH 4 ) 2 C 2 O 4 •H 2 O 2 . The compound (NH 4 ) 2 C 2 O 4 ‚H 2 O 2 was further confirmed by Schreinemaker's wet residue method. The hydrate (NH 4 ) 2 C 2 O 4 ‚H 2 O has a bigger crystallization field than either (NH 4 ) 2 C 2 O 4 ‚H 2 O 2 or the mixture of (NH 4 ) 2 C 2 O 4 ‚H 2 O and (NH 4 ) 2 C 2 O 4 ‚H 2 O 2 . The solubilities of (NH 4 ) 2 C 2 O 4 ‚H 2 O increased sharply with an increase in the concentration of hydrogen peroxide and increased slightly with increasing temperature.