Potassium tree leaves, adding water, heating, and evaporating the solution. When Humphry Davy first isolated the pure element using electrolysis in 1807, he named it "potassium", which he derived from the word potash. The symbol "K" stems from "kali", itself from the root word "alkali", which in turn comes from "" "al-qalyah" "plant ashes." In 1797, the German chemist Martin Klaproth discovered "potash" in the minerals leucite and lepidolite, and realized that "potash" was not a product of plant growth but actually contained a new element, which he proposed to call "kali". In 1807, Humphry Davy produced the element via electrolysis:
Potassium pyrosulfate Potassium pyrosulfate Potassium pyrosulfate, or potassium disulfate, is an inorganic compound with the chemical formula KSO. Potassium pyrosulfate is obtained by the thermal decomposition of other salts, most directly from potassium bisulfate: Temperatures above 600°C further decompose potassium pyrosulfate to potassium sulfate and sulfur trioxide however: Other salts, such as potassium trisulfate, can also decompose into potassium pyrosulfate. 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 anion's configuration and a centrally bridged oxygen atom. A semi-structural formula for the pyrosulfate anion is