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Potassium carbonate

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Title: Potassium carbonate  
Author: World Heritage Encyclopedia
Language: English
Subject: Potash, Potassium bicarbonate, Carbonate, Potassium permanganate, Sodium carbonate
Collection: Carbonates, Deliquescent Substances, Desiccants, Leavening Agents, Photographic Chemicals, Potassium Compounds
Publisher: World Heritage Encyclopedia

Potassium carbonate

Potassium carbonate
IUPAC name
Potassium carbonate
Other names
Carbonate of potash, Dipotassium carbonate, Sub-carbonate of potash, Pearl ash, Potash, Salt of tartar, Salt of wormwood.
ChemSpider  Y
Jmol-3D images Image
RTECS number TS7750000
Molar mass 138.205 g/mol
Appearance white, hygroscopic solid
Density 2.43 g/cm3
Melting point 891 °C (1,636 °F; 1,164 K)
Boiling point decomposes
112 g/100 mL (20 °C)
156 g/100 mL (100 °C)
Solubility insoluble in alcohol, acetone
Safety data sheet ICSC 1588
GHS pictograms The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word Warning
H302, H315, H319, H335
P261, P305+351+338
Harmful Xn
R-phrases R22 R36 R37 R38
NFPA 704
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
LD50 (Median dose)
1870 mg/kg (oral, rat)[1]
Related compounds
Other anions
Potassium bicarbonate
Other cations
Lithium carbonate
Sodium carbonate
Rubidium carbonate
Caesium carbonate
Related compounds
Ammonium carbonate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
 N  (: Y/N?)

Potassium carbonate (K2CO3) is a white salt, soluble in water (insoluble in ethanol[2]), 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 1
  • Production 2
  • Applications 3
  • References 4
  • Bibliography 5
  • External links 6


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

In late 18th century North America, before the development of baking powder, pearl ash was used as a leavening agent in quick breads.[3]


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


  • (historically) for soap, glass, and china production
  • as a mild [4]
  • In cuisine, it is used as an ingredient in the production of grass jelly, a food consumed in Chinese and Southeast Asian cuisines. It is used to tenderize tripe. German gingerbread recipes often use potassium carbonate as a baking agent.
  • Used in the production of cocoa powder to balance the pH (i.e. reduce the amount of acidity) of natural cocoa beans (it also helps enhance the aroma). The process of adding potassium carbonate to cocoa powder is usually called "Dutching", or Dutch-processed cocoa powder, as the process was first developed in 1828 by Coenrad Johannes van Houten, a Dutchman.
  • as a buffering agent in the production of mead or wine.
  • softening hard water.[5]
  • as a fire suppressant in extinguishing deep-fat fryers and various other B class-related fires
  • in condensed aerosol fire suppression, although as the byproduct of potassium nitrate.
  • an ingredient in welding fluxes, and in the flux coating on arc-welding rods.
  • stability in neurons to help maintain equilibrium.
  • as an animal feed ingredient to satisfy the potassium requirements of farmed animals such as broiler breeders


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


A Dictionary of Science, Oxford University Press, New York, 2004

External links

  • International Chemical Safety Card 1588
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