In 1807, potassium metal was first isolated using an
electrolysis apparatus. When electrodes were
immersed in a bath of molten potassium hydroxide and a voltage was applied across the electrodes,
liquid potassium metal collected around the
cathode. A few months later, the same procedure
was used to isolate
sodium metal.
Pure potassium metal is very soft. It reacts with the
oxygen in dry air to produce a powerful
oxidizing agent, potassium superoxide, K2O.
In moist air, potassium hydroxide, KOH, is produced. Because of its instability in air,
potassium is usually stored in kerosene.
Potassium chloride, KCl, occurs in many natural deposits. Enormous deposits are located in Saskatchewan,
Canada. The fertilizer industry refers to any potassium salt as
potash.
The main salts used are the chloride, KCl, the nitrate, KNO3, and the sulphate,
K2SO4. Canada produces about 25% of the world production of potash from
deposits in the Prairie Evaporite Formation in Saskatchewan.
Listed below are the principal uses of potassium are in the form of compounds:
Potassium bromide, KBr, is extensively used in the manufacture of photographic
plates, films, and papers.
Potassium chlorate, KClO3, is a powerful
oxidizing agent. It is used in explosives,
matches, weedkillers, fireworks, and
disinfectant.
Potassium chloride, KCl, is the most abundant of potassium compounds. It is perhaps best known as
a no-sodium table salt substitute. It is also an ingredient in many chemical
fertilizers and is used in the manufacture of other chemicals.
Potassium hydroxide, KOH, is often called caustic potash.
It is used in the manufacture of soaps and detergents. It is a good drain cleanser
because it combines with grease (that clog drains) to form water soluble soaps.
Potassium carbonate, K2CO3, is used in the laboratory
as a drying agent and industrially in the manufacture of soft soap, hard glass, and in the dyeing
industry.
Potassium iodide, KI, is used in medicine, particularly in the treatment of
goitre resulting from iodine deficiency.
Potassium nitrate, KNO3, is used in chemical fertilizers,
in gunpowder and match heads.
Potassium permanganate, KMnO4, is a purple solid soluble in water. It is
used in volumetric analysis as an oxidizing agent. It is also used as a bactericide and a
disinfectant.
Potassium sulfate, K2SO4, is used as a fertilizer, particularly
for tobacco plants, and in the chemical industry in the preparation of
alums.
Potassium superoxide, K2O, is used in the respiratory equipment because
it efficiently generates fresh oxygen while removing carbon dioxide.
