Diammonium phosphate: Difference between revisions

| Watchedfields = changed

| verifiedrevid = 460781413

| ImageSize =

| OtherNames = ammonium monohydrogen phosphate, ammonium hydrogen phosphate, ammonium phosphate dibasic

| Reference = <ref name="hand">Pradyot Patnaik. ''Handbook of Inorganic Chemicals''. McGraw-Hill, 2002, {{ISBN|0-07-049439-8}}</ref>

|Section1={{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChEBI = 63051

| SMILES = [NH4+].[NH4+].OP([O-])([O-])=O

| 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) <br/> 106.7 g/100 mL (70 °C)

| SolubleOther = insoluble in [[ethanol|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]]<br/>[[Triammonium phosphate]]

| OtherCations = [[Disodium phosphate]]<br/>[[Dipotassium phosphate]]

| OtherCompounds = [[Ammonium nitrate]]<br/>[[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]] [[salt (chemistry)|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:<ref>{{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}}</ref>

:{{chem2|(NH4)2HPO4(s) <-> NH3(g) + (NH4)H2PO4(s)}}

At 100&nbsp;°C, the dissociation pressure of diammonium phosphate is approximately 5 mmHg.<ref>{{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}}</ref>

According to the diammonium phosphate [[Safety data sheet|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 oxide]]s and ammonia."

DAP is used as a [[fertilizer]].<ref name=IPNI2014>{{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

}}</ref> 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.<ref name='IPNI - DAP'>{{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 }}</ref> The typical formulation is 18-46-0 (18% N, 46% P₂O₅, 0% K₂O).<ref name="IPNI - DAP" />

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.<ref>{{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}}</ref> These are important effects in fighting [[wildfires]] as lowering the [[pyrolysis]] temperature and increasing the amount of [[Char (chemistry)|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.<ref name="phoscheck">[https://www.perimeter-solutions.com/wp-content/uploads/2021/08/PHOS-CHEK-259-Fx-Solution-EN-OSHA-WHMIS-GHS-SDS-2020-03-04.pdf Phos-Chek MSDS], Phos-Chek website.</ref>

DAP is also used as a [[yeast assimilable nitrogen|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 (metallurgy)|flux]] for soldering tin, copper, zinc and brass; and to control [[precipitation (chemistry)|precipitation]] of alkali-soluble and acid-insoluble colloidal dyes on [[wool]].<ref name="hand"/>

==Natural occurrence==

The compound occurs in the nature as the exceedingly rare mineral phosphammite.<ref name="auto2">{{Cite web|url=https://www.mindat.org/min-3197.html|title=Phosphammite|website=www.mindat.org|access-date=8 November 2020}}</ref><ref name="auto">{{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}}</ref> The related dihydrogen compound occurs as the mineral biphosphammite.<ref name="auto1">{{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}}</ref><ref name="auto"/> Both are related to guano deposits.<ref name="auto2"/><ref name="auto1"/>

==External links==

*[http://www.inchem.org/documents/icsc/icsc/eics0217.htm International Chemical Safety Card 0217]

{{Ammonium salts}}

{{Phosphates}}

[[Category:Ammonium compounds]]

[[Category:Phosphates]]

[[Category:Inorganic fertilizers]]