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Potassium carbonate

Carbonate of potash redirects here. For one of potassium carbonate's impure forms, see potash.
Potassium carbonate
IUPAC name Potassium carbonate
Other names Potash, pearlash
CAS number 584-08-7
RTECS number TS7750000
Molecular formula K2CO3
Molar mass 138.2055 g/mol
Appearance White deliquescent solid
Density 2.29 g/cm3, solid
Melting point

891 °C

Boiling point


Solubility in water 112 g/100 mL (20 °C)
NFPA 704
Flash point Not flammable
Related Compounds
Other cations Lithium carbonate, sodium carbonate, caesium carbonate
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

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.



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 pearlash.

In late 18th century North America, before the development of baking powder, pearlash began to be 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


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 potassium compounds.

2KOH + CO2 → K2CO3 + H2O


Pearlash 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.


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

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Potassium_carbonate". A list of authors is available in Wikipedia.
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