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Potassium sulfate (K2SO4) (also known as potash of sulfur) is a non-flammable white crystalline salt which is soluble in water. The chemical is commonly used in fertilizers, providing both potassium and sulfur.
History Potassium sulfate (K2SO4) has been known since early in the 14th century, and it was studied by Glauber, Boyle and Tachenius. In the 17th century it was named arcanuni or sal duplicatum, as it was a combination of an acid salt with an alkaline salt. Natural resources Natural resources of potassium sulfate are minerals abundant in the Stassfurt salt. These are cocrystalisations of potassium sulfate and sulfates of magnesium calcium and sodium. The minerals are From some of the minerals like kainite, the potassium sulfate can be separated, because the corresponding salt is less soluble in water. With potassium chloride kieserit MgSO4 • 2 H20 can be transformed and then the potassium sulfate can be dissolved in water. Manufacture To purify the crude product, it can be dissolved in hot water and then filtered and cooled, causing the bulk of the dissolved salt to crystallize with characteristic promptitude. Properties The very beautiful (anhydrous) crystals form a double six-sided pyramid, but are in fact classified as rhombic. They are transparent, very hard and absolutely resistant to corrosion and have a bitter, salty taste. The salt is soluble in water, but insoluble in solutions of potassium hydroxide (sp. gr. 1.35), or in absolute ethanol. It melts at 1078 °C. Uses The principal use of potassium sulfate is as a fertilizer. The crude salt is also used occasionally in the manufacture of glass. Potassium hydrogen sulfate Potassium hydrogen sulfate or bisulfate, KHSO4, is readily produced by mixing K2SO4 with an equivalent no. of moles of sulfuric acid. It forms rhombic pyramids, which melt at 197 °C. It dissolves in three parts of water of 0°C. The solution behaves much as if its two congeners, K2SO4 and H2SO4, were present side by side of each other uncombined; an excess of ethanol the precipitates normal sulfate (with little bisulfate) with excess acid remaining. Similar is the behavior of the fused dry salt when heated to several hundred degrees; it acts on silicates, titanates, etc., the same way as sulfuric acid that is heated beyond its natural boiling point does. Hence it is frequently used in analytical chemistry as a disintegrating agent. For information about other salts that contain sulfate, see sulfate. See also | |||||||||||||
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