Potassium pyrosulfate

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:

2 KHSO₄ → K₂S₂O₇ + H₂O

Temperatures above 600°C further decompose potassium pyrosulfate to potassium sulfate and sulfur trioxide however:

K₂S₂O₇ → K₂SO₄ + SO₃

Other salts, such as potassium trisulfate, 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. A semi-structural formula for the pyrosulfate anion is O₃SOSO₃^{2<nowiki>&minus;</nowiki>}. 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.

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

See also

• Sodium pyrosulfate

References