Potassium sulfate (K2SO4) (in British English
potassium sulphate, also called
sulphate of potash,
arcanite, or archaically 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 (K
2SO
4) 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. It was also know as
vitriolic tartar.
Natural resources
The mineral form of potassium sulfate, namely arcanite, is relatively rare. 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 kieserite MgSO
4 • 2 H
2O can be transformed and then the potassium sulfate can be dissolved in water.
Manufacture
- Potassium sulfate can be synthesised by the decomposition of potassium chloride with sodium sulfate.
- The Hargreaves method is basically the same process with different starting materials. Sulfur dioxide, oxygen and water (the starting materials for sulfuric acid) are reacted with potassium chloride. Hydrochloric acid evaporates off.
- Potassium Sulfate is produced by mixing the following:
Potassium Chloride and Sulfuric Acid(with molar ratio).
2KCl + H
2SO
4 → 2HCl + K
2SO
4 Properties
The
anhydrous crystals form a double six-sided pyramid, but are in fact classified as rhombic. They are transparent, very hard 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, KHSO
4, is readily produced by mixing K
2SO
4 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 at 0°C. The solution behaves much as if its two
congeners, K
2SO
4 and H
2SO
4, were present side by side of each other uncombined; an excess of ethanol the precipitates normal sulfate (with little bisulfate) with excess acid remaining.
The behavior of the fused dry salt is similar 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
Category:Potassium compoundsCategory:SulfatesCategory:Fertilizersbs:Kalijum sulfatcs:Síran draselnýde:Kaliumsulfatfr:Sulfate de potassiumid:Kalium sulfatit:Solfato di potassiolv:Kālija sulfātslt:Kalio sulfataslmo:Sulfaa de putassihu:Kálium-szulfátnl:Kaliumsulfaatja:硫酸カリウムnn:Kaliumsulfatpt:Sulfato de potássiosr:Калијум-сулфатfi:Kaliumsulfaattisv:Kaliumsulfatuk:Сульфат каліюvec:Solfato de potasiovi:Sulfat kalizh:硫酸钾
