Potassium pyrosulfate
# Potassium pyrosulfate

Potassium pyrosulfate, or potassium disulfate, is an inorganic compound with the chemical formula $K_2S_2O_7.$

## Production

Potassium pyrosulfate is obtained by the thermal decomposition of other salts, most directly from potassium bisulfate:

    2 $KHSO_4$ → $K_2S_2O_7$ + $H_2O$

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

    $K_2S_2O_7$ → $K_2SO_4$ + $SO_3$

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 $SO_4$ anion's configuration and a centrally bridged oxygen atom. A semi-structural formula for the pyrosulfate anion is $O_3SOSO_3^{2−}.$ 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.

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

