potassium pyrosulfate
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 429083580
| ImageFile=Potassium pyrosulfate.png
| ImageClass = skin-invert-image
| ImageSize=
| IUPACName=dipotassium (sulfonatooxy)sulfonate
| OtherNames=Potassium pyrosulphate; potassium disulfate
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|??}}
| CASNo=7790-62-7
| PubChem=62681
| EINECS = 232-216-8
| UNII = AVJ6ZST7L6
| SMILES=[O-]S(=O)(=O)OS(=O)(=O)[O-].[K+].[K+]
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 56432
| InChI = 1/2K.H2O7S2/c;;1-8(2,3)7-9(4,5)6/h;;(H,1,2,3)(H,4,5,6)/q2*+1;/p-2
| InChIKey = KAQHZJVQFBJKCK-NUQVWONBAQ
| StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| StdInChI = 1S/2K.H2O7S2/c;;1-8(2,3)7-9(4,5)6/h;;(H,1,2,3)(H,4,5,6)/q2*+1;/p-2
| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| StdInChIKey = KAQHZJVQFBJKCK-UHFFFAOYSA-L
}}
|Section2={{Chembox Properties
| K=2 | S=2 | O=7
| Appearance=
| Density= 2.28 g/cm3
| MeltingPtC= 325
| BoilingPtC=
| Solubility= 25.4 g/100 mL (20 °C)
}}
|Section3={{Chembox Hazards
| AutoignitionPt =
| FlashPt=
| MainHazards=
| NFPA-H =
| NFPA-F =
| NFPA-R =
| NFPA-S =
| PEL =
| GHSPictograms = {{GHS05}}{{GHS06}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|314|331}}
| PPhrases = {{P-phrases|260|261|264|271|280|301+330+331|303+361+353|304+340|305+351+338|310|311|321|363|403+233|405|501}}
}}
}}
Potassium pyrosulfate, or potassium disulfate, is an inorganic compound with the chemical formula K2S2O7.
Production
Potassium pyrosulfate is obtained by the thermal decomposition of other salts, most directly from potassium bisulfate:{{cite book|last1=Washington Wiley|first1=Harvey|title=Principles and Practice of Agricultural Analysis: Fertilizers|date=1895|publisher=Chemical Publishing Co.|location=Easton, PA.|page=[https://archive.org/details/principlesandpr03wilegoog/page/n232 218]|url=https://archive.org/details/principlesandpr03wilegoog|quote=Potassium disulfate.|access-date=31 December 2015}}
: 2 KHSO4 → K2S2O7 + H2O
Temperatures above 600°C further decompose potassium pyrosulfate to potassium sulfate and sulfur trioxide however:{{cite book|last1=Iredelle Dillard Hinds|first1=John|title=Inorganic Chemistry: With the Elements of Physical and Theoretical Chemistry|date=1908|publisher=John Wiley & Sons.|location=New York|page=[https://archive.org/details/inorganicchemist00hinduoft/page/547 547]|url=https://archive.org/details/inorganicchemist00hinduoft|quote=Potassium disulfate.|access-date=31 December 2015}}
: K2S2O7 → K2SO4 + SO3
Other salts, such as potassium trisulfate,{{cite book|last=Brauer|first=Georg|title=Handbook of Preparative Inorganic Chemistry Vol. 2, 2nd Ed.|date=1963|publisher=Academic Press|location=New York|isbn=9780323161299|page=1716|url=https://books.google.com/books?id=Pef47TK5NfkC}} can also decompose into potassium pyrosulfate.
Chemical structure
Potassium pyrosulfate contains the pyrosulfate anion which has a dichromate-like structure. The geometry can be visualized as a tetrahedron with two corners sharing the SO4 anion's configuration and a centrally bridged oxygen atom.{{cite journal |title=The crystal structure determination and refinements of K2S2O7, KNaS2O7 and Na2S2O7 from X-ray powder and single crystal diffraction data |last=Ståhl |first=K. |last2=Balic-Zunic |first2=T. |last3=da Silva |first3=F. |last4=Eriksen |first4=K. M. |last5=Berg |first5=R. W. |last6=Fehrmann |first6=R. |journal=Journal of Solid State Chemistry |volume=178 |issue=5 |pages=1697–1704 |year=2005 |doi=10.1016/j.jssc.2005.03.022 |bibcode = 2005JSSCh.178.1697S |url=http://orbit.dtu.dk/en/publications/the-crystal-structure-determination-and-refinements-of-k2s2o7-knas2o7-and-na2s2o7-from-xray-powder-and-single-crystal-diffraction-data(9509b129-d51a-4a6b-8972-5cb4ca003ad0).html |url-access=subscription }} A semi-structural formula for the pyrosulfate anion is O3SOSO32
Uses
Potassium pyrosulfate is used in analytical chemistry; samples are fused with potassium pyrosulfate, (or a mixture of potassium pyrosulfate and potassium fluoride) to ensure complete dissolution prior to a quantitative analysis.{{cite journal |title=Determination of quartz (free silica) in refractory clays |last=Trostbl |first=L. J. |last2=Wynne |first2=D. J. |journal=Journal of the American Ceramic Society |volume=23 |issue=1 |pages=18–22 |year=1940 |doi=10.1111/j.1151-2916.1940.tb14187.x }}{{cite journal |title=Determination of gross alpha, plutonium, neptunium, and/or uranium by gross alpha counting on barium sulphate |first=C. W. |last=Sill |journal=Analytical Chemistry |year=1980 |volume=52 |issue=9 |pages=1452–1459 |doi=10.1021/ac50059a018 }}
The compound is also present in a catalyst in conjunction with vanadium(V) oxide in the industrial production of sulfur trioxide.{{cite web|last1=Burkhardt|first1=Donald|year=1965|title=Sulfur trioxide production, US3362786A|url=https://patents.google.com/patent/US3362786A/en|website=Google Patents|access-date=31 December 2015}}