View source for Phosphoric acid

{{Compound|chemf=H3PO4|nfpa_h=3|mm=97.995|mp=42.35|bp=158 (decomp)|group=Mineral Acids|decomp={{DecompRow|input=Phosphoric acid|temp=158|output={{#Chem: H2O + HPO3}}}}|stp_p=solid|stp_q=white|industrial=yes|sol_aq=3922|sol_et=misc|ior=1.4320 (85% aq. soln, 25°C)}}
==Uses==
===Primary===
* Industrial chemical (early accessible mineral acid)
* Fertilizer
===Secondary===
* Can be used to produce [[hydrochloric acid|hydrochloric]] and [[nitric acid]]s.
*: {{#Chem: H3PO4 + 3NaCl { = 110&deg;C } Na3PO4 + 3HCl(g) // Escaping HCl  vapors keep reaction moving to the right}}
*: {{#Chem: H3PO4 + 3NaNO3 { = 120.5&deg;C } Na3PO4 + 3 HNO3(g) // Escaping HNO<sub>3</sub> vapors keep reaction moving to the right}}

==Natural Occurrence==
* Phosphoric '''does not''' occur naturally in quantity. If generated (by volcano, lightening, etc) it rapidly reacts with nearby materials and becomes phosphate.
==Hazards==
==Character==
* 85% phosphoric acid has a density of approximately 1.65g/cc
==Production==
===Synthesis===
====From phosphorus====
# Burn [[phosphorus]], producing ''phosphorus pentoxide''
#: {{#Chem:  P4 + 5O2 --> 2P2O5 }}
# Dissolve ''phosphorus pentoxide'' in water producing phosphoric acid
#: {{#Chem:  3 H2O + P2O5 = 2 H3PO4 }}
====From copper sulfate====
Combine phosphorus with a [[copper sulfate]] solution leaving sulfuric and phosphoric acid along with metallic copper.
<ref name=Bird>{{cite pub
|title=POSITIVE IONS FROM NON METALLIC ELEMENTS|subtitle=A STUDY OF THE PRECIPITATION OF METALS FROM SOLUTIONS OF THEIR SALTS BY YELLOW PHOSPHORUS|year=1914|first1=R.M.|last1=Bird|first2=S.H.|last2=Diggs|publication=Journal of the American Chemical Society|volume=XXXVI|pages=1383|url=http://books.google.com/books?id=PCo1AQAAMAAJ&pg=PA1383#v=onepage&q&f=false}}</ref>
Combine white [[phosphorus]] with a solution of [[copper sulfate]]
: {{#Chem: 5 CuSO4 + 2P + 8H2O --> 5Cu+5H2SO4+2H3PO4}}
===Extraction===
====From apatite====
Phosphoric acid is synthesized by treating [[apatite]] (mostly calcium triphosphate) with [[sulfuric acid]], producing phosphoric acid, water, and [[gypsum]].
:{{#Chem: Ca5(PO4)3X+5H2SO4+10H2O --> 3H3PO4+5CaSO4*2H2O+HX}} where X &isin; {OH, F, Cl, Br}
Thus if fluorapatite is used, '''hydrofluoric acid''' will be produced in recoverable amounts.
====From bone black====
Phosphoric acid is synthesized by treating [[bone black]] with [[sulfuric acid]], producing phosphoric acid, and calcium sulfate (dihydrate)
:{{#Chem: Ca3(PO4)2+3H2SO4+6H2O-->2H3PO4+3CaSO4*2H2O}}
==Purification==
Much like '''sulfur trioxide''' can be introduced into dilute [[sulfuric acid]] to concentrate it, burnt [[phosphorus]] introduced into dilute phosphoric acid produces more concentrated phosphoric acid.
: {{#Chem: 3H2O + P2O5 --> 2H3PO4}} (Catalyzed by existing phosphoric acid)
==Testing==
==Storage==
==Disposal==

==See Also==
*{{Cite pub|title=Ueber die Reduction der Quecksilbersalze durch Kupfer.|last1=Vogel|first1=A.|year=1836|publication=J. Prakt. Chem.|volume=8|issue=1|pages=107–109|doi=10.1002/prac.18360080118}}
*{{cite pub|title=Phosphorus, reactions between copper and yellow|last1=Straub|first1=Walther|year=1903|publication=Journal of the Chemical Society|volume=84|issue=2|publisher=Gurney & Jackson|url=http://books.google.com/books?id=8r0wAAAAYAAJ&lpg=PA593&ots=tkut6O_qb5&pg=PA593#v=onepage&q&f=false}}
==References==
<references/>