potassium carbonate, chemical compound, K₂CO₃, white, crystalline, deliquescent substance that forms a strongly alkaline water solution. It is available commercially as a white, granular powder commonly called potash, or pearl ash. It was originally obtained from wood ashes or from the residue left in pots after certain plants, e.g., kelp, were burned in them. It is prepared commercially chiefly by electrolysis of potassium chloride to form potassium hydroxide, which is then carbonated (e.g., by adding carbon dioxide gas). It is used in the manufacture of soft soaps and glass, for washing wool, and in the production of other potassium compounds.

Carbonate of potash redirects here. For one of potassium carbonate's impure forms, see potash.

Potassium carbonate is a white salt, soluble in water (insoluble in alcohol), which forms a strongly alkaline solution. It can be made as the product of potassium hydroxide's absorbent reaction with carbon dioxide. It is deliquescent, often appearing a damp or wet solid. Potassium carbonate is used in the production of soap and glass.

History

Potassium carbonate was first identified in 1742 by Antonio Campanella and is the primary component of potash and the more refined pearlash or salts of tartar. Historically pearlash was created by baking potash in a kiln to remove impurities. The fine white powder remaining was the pearlash. The first patent issued by the U.S. Patent Office was awarded to Samuel Hopkins in 1790 for an improved method of making potash and pearlash.

In late 18th century North America, before the development of baking powder, pearl ash was used as a leavening agent in "quick breads".

Other terms for potassium carbonate:

• Carbonate of potash
• Dipotassium carbonate
• Dipotassium salt
• Pearl ash
• Potash
• Salt of tartar
• Salt of wormwood

Production

Today potassium carbonate is prepared commercially by the electrolysis of potassium chloride. The resulting potassium hydroxide is then carbonated using carbon dioxide to form potassium carbonate, which is often used to produce other .

2KOH + CO₂ → K₂CO₃ + H₂O

Applications

Pearl ash has been used for soap, glass, and china production.

In the laboratory, it may be used as a mild drying agent where other drying agents such as calcium chloride may be incompatible. However, it is not suitable for acidic compounds.

Mixed with water it causes an exothermic reaction that results in a temperature change, producing heat.

In cuisine, it is used as an ingredient in the production of grass jelly, a food consumed in Chinese and Southeast Asian cuisines.

Potassium carbonate is being used as the electrolyte in many cold fusion experiments.

Potassium carbonate is sometimes used as a buffering agent in the production of mead or wine.

Aqueous potassium carbonate is also used as a fire suppressant in extinguishing deep fat fryers and various other B class related fires.

Potassium carbonate is used in reactions to maintain anhydrous conditions without reacting with the reactants and product formed. It may also be used to pre-dry some ketones, alcohols, and amines prior to distillation.

References

Bibliography

A Dictionary of Science, Oxford University Press Inc., New York 2003

External links

• International Chemical Safety Card 1588