Potassium pyrosulfate explained

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:^[1]

2 KHSO₄ → K₂S₂O₇ + H₂OTemperatures above 600°C further decompose potassium pyrosulfate to potassium sulfate and sulfur trioxide however:^[2]

K₂S₂O₇ → K₂SO₄ + SO₃

Other salts, such as potassium trisulfate,^[3] 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.^[4] A semi-structural formula for the pyrosulfate anion is O₃SOSO₃^2−. The oxidation state of sulfur in this compound is +6.

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.^{[5] [6]}

The compound is also present in a catalyst in conjunction with vanadium(V) oxide in the industrial production of sulfur trioxide.^[7]

See also

• Sodium pyrosulfate

Notes and References

1. Book: Washington Wiley. Harvey. Principles and Practice of Agricultural Analysis: Fertilizers. 1895. Chemical Publishing Co.. Easton, PA.. 218. Potassium disulfate.. 31 December 2015.
2. Book: Iredelle Dillard Hinds. John. Inorganic Chemistry: With the Elements of Physical and Theoretical Chemistry. 1908. John Wiley & Sons.. New York. 547. Potassium disulfate.. 31 December 2015.
3. Book: Brauer, Georg. Handbook of Preparative Inorganic Chemistry Vol. 2, 2nd Ed.. 1963. Academic Press. New York. 9780323161299. 1716.
4. The crystal structure determination and refinements of K₂S₂O₇, KNaS₂O₇ and Na₂S₂O₇ from X-ray powder and single crystal diffraction data . Ståhl . K. . Balic-Zunic . T. . da Silva . F. . Eriksen . K. M. . Berg . R. W. . Fehrmann . R. . Journal of Solid State Chemistry . 178 . 5 . 1697–1704 . 2005 . 10.1016/j.jssc.2005.03.022 . 2005JSSCh.178.1697S .
5. Determination of quartz (free silica) in refractory clays . Trostbl . L. J. . Wynne . D. J. . Journal of the American Ceramic Society . 23 . 1 . 18–22 . 1940 . 10.1111/j.1151-2916.1940.tb14187.x .
6. Determination of gross alpha, plutonium, neptunium, and/or uranium by gross alpha counting on barium sulphate . C. W. . Sill . Analytical Chemistry . 1980 . 52 . 9 . 1452–1459 . 10.1021/ac50059a018 .
7. Web site: Burkhardt. Donald. 1965. Sulfur trioxide production, US3362786A. Google Patents. 31 December 2015.