Carbonate of potash, Dipotassium carbonate, Sub-carbonate of potash, Pearl ash, Potash, Salt of tartar, Salt of wormwood.
|Molar mass||138.205 g/mol|
|Appearance||white, hygroscopic solid|
|Melting point||891 °C (1,636 °F; 1,164 K)|
|112 g/100 mL (20 °C)
156 g/100 mL (100 °C)
|Solubility||insoluble in alcohol, acetone|
|EU Index||Not listed|
|R-phrases||R22 R36 R37 R38|
LD50 (Median lethal dose)
|1870 mg/kg (oral, rat)|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
Potassium carbonate (K2CO3) is a white salt, soluble in water (insoluble in ethanol), 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 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.
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 drying agent where other drying agents, such as calcium chloride and magnesium sulfate, may be incompatible. 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. It may also be used to dry some ketones, alcohols, and amines prior to distillation.
- 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.
- 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
- See references to "pearl ash" in "American Cookery" by Amelia Simmons, printed by Hudson & Goodwin, Hartford, 1796.
- Leonard, J.; Lygo, B.; Procter, G. "Advanced Practical Organic Chemistry" 1998, Stanley Thomas Publishers Ltd
- Child, Lydia M. "The American Frugal Housewife" 1832