- Diammonium phosphate
-
Diammonium phosphate[1] 
diammonium hydrogen phosphateOther namesammonium monohydrogen phosphate, ammonium phosphate dibasicIdentifiers CAS number 7783-28-0 
PubChem 24540 ChemSpider 22946 UNII 10LGE70FSU Jmol-3D images Image 1 - [NH4+].[NH4+].[O-]P([O-])([O-])=O
- InChI=1S/2H3N.H3O4P/c;;1-5(2,3)4/h2*1H3;(H3,1,2,3,4)/p-1
Key: MNNHAPBLZZVQHP-UHFFFAOYSA-M
InChI=1/2H3N.H3O4P/c;;1-5(2,3)4/h2*1H3;(H3,1,2,3,4)/p-1
Key: MNNHAPBLZZVQHP-REWHXWOFAG
Properties Molecular formula (NH4)2HPO4 Molar mass 132.07 g/mol Appearance white powder Density 1.619 g/cm3 Melting point 155 ºC decomp.
Solubility in water 57.5 g/100 mL (10 ºC)
106.7 g/100 mL (100 °C)Solubility insoluble in alcohol, acetone and liquid ammonia Refractive index (nD) 1.52 Thermochemistry Std enthalpy of
formation ΔfHo298-1566.91 kJ/mol Hazards MSDS ICSC 0217 EU Index Not listed NFPA 704 
021Flash point Non-flammable Related compounds Other anions Monoammonium phosphate
Triammonium phosphateOther cations Disodium phosphate
Dipotassium phosphateRelated compounds Ammonium nitrate
Ammonium sulfate
phosphate (verify) (what is: 
/
?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)Infobox references Diammonium phosphate (DAP) (chemical formula (NH4)2HPO4, IUPAC name diammonium hydrogen phosphate) is one of a series of water-soluble ammonium phosphate salts which can be produced when ammonia reacts with phosphoric acid. Solid diammonium phosphate shows a dissociation pressure of ammonia as given by the following expression and equation:[2]
- (NH4)2HPO4(s)
NH3(g) + NH4H2PO4(s)
- log PmmHg = -3063 / T + 175 log T + 3.3
where:
- P = the resultant dissociation pressure of ammonia
- T = absolute temperature (K)
At 100ºC, the dissociation pressure of diammonium phosphate is approximately 5 mmHg.[3]
Uses
DAP is used as a fertilizer. When applied as plant food, it temporarily increases the soil pH, but over a long term the treated ground becomes more acidic than before upon nitrification of the ammonium. It is incompatible with alkaline chemicals because its ammonium ion is more likely to convert to ammonia in a high-pH environment.
DAP can be used as a fire retardant. It lowers the combustion temperature of the material, decreases maximum weight loss rates, and causes an increase in the production of residue or char.[4] These are important effects in fighting wildfires as lowering the pyrolysis temperature and increasing the amount of char formed reduces that amount of available fuel and can lead to the formation of a firebreak. It is the largest component of some popular commercial firefighting products.[5]
DAP is also used as a yeast nutrient in winemaking and brewing mead; as an additive in some brands of cigarettes purportedly as a nicotine enhancer; to prevent afterglow in matches, in purifying sugar; as a Flux for soldering tin, copper, zinc and brass; and to control precipitation of alkali-soluble and acid-insoluble colloidal dyes on wool. [1]
External links
References
- ^ a b Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0070494398
- ^ John R Van Wazer (1958). Phosphorus And Its Compounds - Volume I: Chemistry. New York: Interscience Publishers, Inc. p. 503.
- ^ McKetta Jr, John J., ed (1990). Encyclopedia of Chemical Processing and Design (Chemical Processing and Design Encyclopedia). New York: Marcel Dekker, Inc. p. 478. ISBN 0824724852. http://books.google.com/?id=z2NLRf0ROx0C&lpg=PA478&dq=%22dissociation%20pressure%22%20ammonium%20phosphate&pg=PA478#v=onepage&q=%22dissociation%20pressure%22%20ammonium%20phosphate.
- ^ George, C.W.; Susott, R.A. (April 1971). "Effects of Ammonium Phosphate and Sulfate on the Pyrolysis and Combustion of Cellulose". Research Paper INT-90 (Intermountain Forest and Range Experiment Station: USDA Forest Service). http://openlibrary.org/b/OL16022833M/Effects_of_ammonium_phosphate_and_sulfate_on_the_pyrolysis_and_combustion_of_cellulose
- ^ Phos-Chek MSDS, Phos-Chek website
Categories:- Ammonium compounds
- Phosphates
- Fertilizers
- Inorganic compound stubs
Wikimedia Foundation. 2010.
