Diammonium phosphate
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| Watchedfields = changed
| verifiedrevid = 460781413
| ImageFile = Diammonium phosphate.png
| ImageSize =
| IUPACName = diammonium hydrogen phosphate
| OtherNames = ammonium monohydrogen phosphate, ammonium hydrogen phosphate, ammonium phosphate dibasic
| Reference = Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, {{ISBN|0-07-049439-8}}
|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 22946
| ChEBI = 63051
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 10LGE70FSU
| InChI = 1/2H3N.H3O4P/c;;1-5(2,3)4/h2*1H3;(H3,1,2,3,4)/p-1
| SMILES = [NH4+].[NH4+].OP([O-])([O-])=O
| InChIKey = MNNHAPBLZZVQHP-REWHXWOFAG
| StdInChI = 1S/2H3N.H3O4P/c;;1-5(2,3)4/h2*1H3;(H3,1,2,3,4)
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = MNNHAPBLZZVQHP-UHFFFAOYSA-N
| CASNo = 7783-28-0
| CASNo_Ref = {{cascite|correct|CAS}}
| PubChem = 24540
}}
|Section2={{Chembox Properties
| Formula = (NH4)2HPO4
| MolarMass = 132.06 g/mol
| Appearance = colorless monoclinic crystals
| Density = 1.619 g/cm3
| MeltingPtC = 155
| MeltingPt_notes = decomposes
| Solubility = 57.5 g/100 mL (10 °C)
106.7 g/100 mL (70 °C)
| SolubleOther = insoluble in alcohol, acetone and liquid ammonia
| RefractIndex = 1.52
}}
|Section4={{Chembox Thermochemistry
| DeltaHf = −1566.91 kJ/mol
| DeltaHc =
| Entropy =
| HeatCapacity =}}
|Section7={{Chembox Hazards
| ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics0217.htm ICSC 0217]
| NFPA-H = 2
| NFPA-F = 0
| NFPA-R = 1
| MainHazards =
| FlashPt = Non-flammable
}}
|Section8={{Chembox Related
| OtherAnions = Monoammonium phosphate
Triammonium phosphate
| OtherCations = Disodium phosphate
Dipotassium phosphate
| OtherCompounds = Ammonium nitrate
Ammonium sulfate
}}
}}
Diammonium phosphate (DAP; IUPAC name diammonium hydrogen phosphate; chemical formula (NH4)2(HPO4)) is one of a series of water-soluble ammonium phosphate salts that 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:{{cite book |title=Phosphorus And Its Compounds - Volume I: Chemistry |page=503 |author=John R Van Wazer |year=1958 |publisher=Interscience Publishers, Inc |place=New York}}
:{{chem2|(NH4)2HPO4(s) <-> NH3(g) + (NH4)H2PO4(s)}}
At 100 °C, the dissociation pressure of diammonium phosphate is approximately 5 mmHg.{{cite book |title=Encyclopedia of Chemical Processing and Design (Chemical Processing and Design Encyclopedia) |editor1-first=John J.|editor1-last=McKetta Jr |year= 1990|publisher=Marcel Dekker, Inc|location= New York|isbn= 0-8247-2485-2|page=478|url= https://books.google.com/books?id=z2NLRf0ROx0C&q=%22dissociation+pressure%22+ammonium+phosphate&pg=PA478}}
According to the diammonium phosphate MSDS from CF Industries, Inc., decomposition starts as low as 70 °C: "Hazardous Decomposition Products: Gradually loses ammonia when exposed to air at room temperature. Decomposes to ammonia and monoammonium phosphate at around 70 °C (158 °F). At 155 °C (311 °F), DAP emits phosphorus oxides, nitrogen oxides and ammonia."
Uses
DAP is used as a fertilizer.{{cite web
| last1 =IPNI
| title =Diammonium Phosphate
| url =http://www.ipni.net/publication/nss.nsf/0/66D92CC07C016FA7852579AF00766CBD/$FILE/NSS-17%20Diammonium%20Phosphate.pdf
| website =www.ipni.net
| publisher =International Plant Nutrition Institute
| access-date =21 July 2014
| archive-url =https://web.archive.org/web/20150924035955/http://www.ipni.net/publication/nss.nsf/0/66D92CC07C016FA7852579AF00766CBD/$FILE/NSS-17%20Diammonium%20Phosphate.pdf
| archive-date =24 September 2015
| url-status =live
}} When applied as plant fertilizer, 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. The average pH in solution is 7.5–8.{{cite web |url= http://www.ipni.net/publication/nss.nsf/0/66D92CC07C016FA7852579AF00766CBD/$FILE/NSS-17%20Diammonium%20Phosphate.pdf |title= Nutrient Source Specifics: Diammonium Phosphate |access-date= 2012-12-10 |author= International Plant Nutrition Institute |archive-url= https://web.archive.org/web/20121021041202/http://www.ipni.net/publication/nss.nsf/0/66D92CC07C016FA7852579AF00766CBD/$FILE/NSS-17%20Diammonium%20Phosphate.pdf |archive-date= 2012-10-21 |url-status= live }} The typical formulation is 18-46-0 (18% N, 46% P2O5, 0% K2O).
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.{{cite journal |last1=George |first1=C.W. |last2=Susott |first2=R.A. |title=Effects of Ammonium Phosphate and Sulfate on the Pyrolysis and Combustion of Cellulose |publisher=USDA Forest Service |journal=Research Paper INT-90 |place=Intermountain Forest and Range Experiment Station |date=April 1971 |ol=16022833M |url=https://openlibrary.org/b/OL16022833M/Effects_of_ammonium_phosphate_and_sulfate_on_the_pyrolysis_and_combustion_of_cellulose}} 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.
DAP is also used as a yeast nutrient in winemaking and mead-making; 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.
Natural occurrence
The compound occurs in the nature as the exceedingly rare mineral phosphammite.{{Cite web|url=https://www.mindat.org/min-3197.html|title=Phosphammite|website=www.mindat.org|access-date=8 November 2020}}{{Cite web|url=https://www.ima-mineralogy.org/Minlist.htm|title=List of Minerals|date=21 March 2011|website=www.ima-mineralogy.org|access-date=8 November 2020}} The related dihydrogen compound occurs as the mineral biphosphammite.{{Cite web |date=3 April 2024 |title=DAP Fertilizer |url=https://thesciencepool.com/dap-fertilizer-a-nutrient-rich-fertilizer/ |access-date=5 April 2024 |website=thesciencepool.com}} Both are related to guano deposits.
References
{{Reflist}}
External links
- [http://www.inchem.org/documents/icsc/icsc/eics0217.htm International Chemical Safety Card 0217]
{{Ammonium salts}}
{{Phosphates}}