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Potassium carbonate
CAS number 584-08-7 Yes check.svgY
PubChem 516886
RTECS number TS7750000
Molecular formula K2CO3
Molar mass 138.205 g/mol
Appearance white, hygroscopic solid
Density 2.29 g/cm3
Melting point

891 °C

Boiling point


Solubility in water 112 g/100 mL (20 °C)
156 g/100 mL (100 °C)
Solubility insoluble in alcohol, acetone
EU Index Not listed
Main hazards Irritant
NFPA 704
NFPA 704.svg
Flash point non-flammable
LD50 1870 mg/kg
Related compounds
Other anions Potassium bicarbonate
Other cations Lithium carbonate
Sodium carbonate
Rubidium carbonate
Caesium carbonate
Related compounds Ammonium carbonate
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Potassium carbonate (K2CO3) 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 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".[1]

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


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

Pearlash added to hard water will soften the water.[2]

In the laboratory, it may be used as a mild drying agent where other drying agents such as calcium chloride and magnesium sulfate may be incompatible. However, it is not suitable for acidic compounds, but can be useful for drying an organic phase if one has a small amount of acidic impurity.

Mixed with water it causes an exothermic reaction.

It is mixed with distilled water to make a safer electrolyte for oxyhydrogen production than potassium hydroxide, the more commonly used electrolyte.

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.[citation needed] It may also be used to pre-dry some ketones, alcohols, and amines prior to distillation.[3]

an ingredient is welding fluxes, and in the flux coating on arc welding rods


  1. ^ See references to "pearl ash" in "American Cookery" by Amelia Simmons, printed by Hudson & Goodwin, Hartford, 1796.
  2. ^ Child, Lydia M. "The American Frugal Housewife" 1832
  3. ^ Leonard, J.; Lygo, B.; Procter, G. "Advanced Practical Organic Chemistry" 1998, Stanley Thomas Publishers Ltd


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

External links


Simple English

Potassium carbonate

Potassium carbonate, also known as potash or pearl ash, is a chemical compound. It is made of potassium and carbonate ions. Its chemical formula is K2CO3.



Potassium carbonate is a white solid. It dissolves in water. It is similar to sodium carbonate. It reacts with acids to make carbon dioxide and a potassium salt. It does not dissolve in alcohol. It is basic. It is a mild drying agent.


It is made by the reaction of carbon dioxide with potassium hydroxide.


It is used to soften water (remove some of the ions from water) and make soap. It is used to put out fires. It can be used as an electrolyte to electrolyze water.

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