RU_KLO - 18-10-2023 at 11:36
hi,
Bought some diammonium phosfate (DAP) from a gardening store in order to make some phosfates. (of course buying phosforic acid would have been
better....)
I want:
1) to obtain phosforic acid. Is there a wet chemical way?
one idea is to:
Decomposes to ammonia and monoammonium phosphate (MAP) at around 70 °C (158 °F). At 155 °C (311 °F), DAP emits phosphorus oxides, nitrogen oxides
and ammonia.
then MAP will decompose when heated to yield water and ammonia vapors, leaving behind polyphosphoric acid residue.
2) is there a risk of phosfine generation? What should be avoided?
from wiki: not to much heat.
"It is prepared in the laboratory by disproportionation of phosphorous acid:[16]
4 H3PO3 → PH3 + 3 H3PO4 Phosphine evolution occurs at around 200 °C."
3) Could be used directly for phosfates production? (as most phosfates are insoluble)
ex: CaCl2 + (NH4)2HPO4(s) -> Ca3(PO4)2 + NH4Cl
(not balanced - dont know if this is correct or other substances are made)
Edit: after reading "SOLUBILITIES OF PHOSPHATES AND OTHER
SPARINGLY SOLUBLE COMPOUNDS - U.S. DEPARTMENT OF COMMERCE
NATIONAL BUREAU OF STANDARDS, it seams that a lots of other Calcium phosfate salts exist, so its not so easy
"The other sparingly soluble calcium phosphates include CaHPO4*2H20,
CaHPO4 , Ca8H2(PO4)6*5H2O and BETA-Ca3(PO4)2 ; two others, tetracalcium phosphate, Ca4O(PO4)2 , and alpha-tricalcium phosphate,
a-Ca3(PO4)2 , do not persist when in contact with aqueous solutions."
but the question is: Could be used directly for phosfates production?
thanks
[Edited on 18-10-2023 by RU_KLO]
Hexabromobenzene - 20-10-2023 at 10:38
Diammonium phosphate decomposes to polyphosphoric acid and ammonia. Polyphosphoric acid may be easy transformated to phosphoric acid. No phosphine
emmited during this.
It also can be used as flux to soldering stainless stell
Also you can prepare Monocalcium phosphate for white phosphorus syntesis. It works well with calcium chloride. Monocalcium phosphate precipitates
Diammonium phosphate, together with ammonia sulfate, can be obtained free in large quantities from old dry powder fire extinguishers. Maybe I'll write
an article
RU_KLO - 21-10-2023 at 15:04
thanks,
This " Polyphosphoric acid may be easy transformated to phosphoric acid."
just by adding water?