What Is Potassium Chloride?

The chemical compound potassium chloride (KCl) is a colorless, crystalline solid. It is basically a metal halide salt containing a halogen atom and closely resembles table salt (sodium chloride). It contains both potassium and chlorine. Pure potassium chloride is white and odorless, but impure potassium chloride could be colored (pink and red). Potassium is sometimes called "muriate of potash," especially when it is used as a fertilizer. Potassium chloride is also used in food processing, laboratory experiments, for the manufacture of other potassium compounds and in medicine.

Production

Potassium chloride occurs naturally in the Stassfurt, Germany, salt deposits as sylvite, a sodium chloride-potassium chloride mineral, and also as carnallite. It can be extracted from sylvite by fractional crystallization and a flotation process. From carnallite, pure potassium chloride is extracted by dissolving the crude mineral in minimum volume of water, and allowed to crystallize when potassium chloride is separated out, while the more soluble magnesium chloride is left in the solution.

Potassium chloride occurs in ocean water, and many minerals can be manufactured by extraction, crystallization and electrostatic separation of suitable minerals. Dried seaweeds are another source of KCl, which contain about 90 percent potassium chloride.

Physical Properties

Potassium chloride is a white crystalline solid material having cubic crystals. Its melting and boiling points are 768 degrees C and 1,411 degrees C, respectively. It is extremely soluble in water, alcohol and alkalis. It resembles sodium chloride in terms of properties, except that its solubility increases quickly with an increase in temperature. Potassium chloride is also easily fusible.

Chemical Properties

Potassium chloride can be used as a source of chlorine ion. Like any other soluble ionic chloride, potassium chloride will give a precipitation of chloride salt when added to a solution containing an appropriate amount of metal ions. Potassium chloride is used to produce metallic potassium. When allowed to react with metallic sodium at 850 degrees C, KCl is reduced to metallic potassium. It is then separated by distillation.

Biological and Medical Properties

Potassium chloride, being the main positive ion inside the living cells, plays an important role in normal bodily functions, including those affecting the nervous system, kidney functions, heart and muscle contraction. It is associated with electrolytic compounds---including calcium, sodium and magnesium---which maintain the balance of the body's electrolyte and water levels.

Use

Potassium chloride is mainly used in the manufacture of K-type potassium fertilizer, because it provides potassium to the soil. The quantity of potassium found in a K-type fertilizer varies, depending on the purity of potassium chloride used.

References

• What Is Potassium Chloride?
• Potassium Chloride
• Ullmann's Encyclopedia of Industrial Chemistry, Volume 1, Issue 13; Barbara Elvers, Fritz Ullmann, Stephen Hawkins, William E. Russey; 1993