:Zinc pyrophosphate
{{chembox
| Verifiedfields = changed
| verifiedrevid = 470636803
| Name = Zinc pyrophosphate
{{Citation
| last = Lide
| first = David R.
| year = 1998
| title = Handbook of Chemistry and Physics
| edition = 87
| location = Boca Raton, Florida
| publisher = CRC Press
| isbn = 0-8493-0594-2
| pages = 4–96
}}
| ImageFile = Zinc_pyrophosphate.svg
| ImageSize = 200px
| ImageName = Zinc pyrophosphate
| OtherNames = Dizinc diphosphate
| Section1 = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 56393
| PubChem = 62641
| InChI = 1/H4O7P2.2Zn/c1-8(2,3)7-9(4,5)6;;/h(H2,1,2,3)(H2,4,5,6);;/q;2*+2/p-4
| InChIKey = OMSYGYSPFZQFFP-XBHQNQODAA
| SMILES = [Zn+2].[Zn+2].[O-]P([O-])(=O)OP([O-])([O-])=O
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/H4O7P2.2Zn/c1-8(2,3)7-9(4,5)6;;/h(H2,1,2,3)(H2,4,5,6);;/q;2*+2/p-4
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = OMSYGYSPFZQFFP-UHFFFAOYSA-J
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 7446-26-6
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 6ERT96A621
}}
| Section2 = {{Chembox Properties
| Formula = Zn2P2O7
| MolarMass = 304.72 g/mol
| Appearance = White crystalline powder
| Density = 3.75 g/cm3
| MeltingPt =
| BoilingPt =
| Solubility = Insoluble
| SolubleOther = Soluble in dilute acids
}}
| Section3 = {{Chembox Structure
| CrystalStruct =
}}
| Section7 = {{Chembox Hazards
| HPhrases =
| PPhrases =
}}
}}
Zinc pyrophosphate (Zn2P2O7) is an ionic inorganic chemical compound composed of Zn2+ cations and pyrophosphate anions.
Preparation
Zinc pyrophosphate can be obtained from the thermal decomposition of zinc ammonium phosphate.{{Cite journal|last=Calvo|first=Crispin|date=1965-05-01|title=THE CRYSTAL STRUCTURE AND PHASE TRANSITIONS OF β-Zn 2 P 2 O 7|journal=Canadian Journal of Chemistry|language=en|volume=43|issue=5|pages=1147–1153|doi=10.1139/v65-152|issn=0008-4042|doi-access=free}}
:2 ZnNH4PO4 → Zn2P2O7 + 2 NH3 + H2O
It can also be obtained from the reaction between sodium carbonate, zinc oxide, and ammonium dihydrogen phosphate.{{Cite journal|last1=Jarboui|first1=A.|last2=Ben Rhaeim|first2=A.|last3=Hlel|first3=F.|last4=Guidara|first4=K|last5=Gargouri|first5=M.|date=2010|title=NMR study and electrical properties investigation of Zn2P2O7|url=http://link.springer.com/10.1007/s11581-009-0333-5|journal=Ionics|language=en|volume=16|issue=1|pages=67–73|doi=10.1007/s11581-009-0333-5|s2cid=94790682 |issn=0947-7047|url-access=subscription}}
:Na2CO3 + 2 ZnO + 2 (NH4)H2PO4 → Zn2P2O7 + 2 NaOH + 2 NH3 + 2 H2O + CO2
It is also produced when a strongly acidic solution of zinc sulfate is heated with sodium pyrophosphate.{{Cite book|last=Ochs|first=Rudolf|url=https://books.google.com/books?id=1hmBBwAAQBAJ&pg=PA117|title=Praktikum der Qualitativen Analyse Für Chemiker · Pharmazeuten und Mediziner|publisher=Springer-Verlag|year=2013|isbn=978-3-662-28315-8|location=Berlin, Heidelberg|pages=117|oclc=860357745}}
:2 ZnSO4 + Na4P2O7 → Zn2P2O7 + 2 Na2SO4
Another method is precipitating zinc as a phosphate, then heating over 1123 K.{{Citation needed|date=May 2009}}
Properties
Zinc pyrophosphate is a white crystalline solid that is insoluble in water.{{Cite book|last=Perry|first=Dale L.|url=https://books.google.com/books?id=SFD30BvPBhoC&pg=PA469|title=Handbook of Inorganic Compounds|publisher=CRC Press|year=2016|isbn=978-1-4398-1462-8|edition=2nd|location=Boca Raton, FL|pages=469|oclc=759865801}} On heating in water, it decomposes to form Zn3(PO4)2 and ZnHPO4. It crystallizes in the monoclinic system. The α-form crystallizes at low temperatures and the β-form crystallizes at high temperatures.
Uses
Zinc pyrophosphate is used as a pigment. It is useful in gravimetric analysis of zinc.{{Cite book|last1=Holleman|first1=Arnold F.|title=Lehrbuch der anorganischen Chemie|last2=Wiberg|first2=Egon|last3=Wiberg|first3=Nils|publisher=de Gruyter|year=1995|isbn=978-3-11-012641-9|edition=102nd|location=Berlin|pages=1493|oclc=237142268}}