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- Carbonate of potash redirects here. For one of potassium carbonate's impure forms, see potash.
| Potassium carbonate | |
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| IUPAC name | Potassium carbonate |
| Other names | Potash, pearl ash |
| Identifiers | |
| CAS number | 584-08-7 |
| RTECS number | TS7750000 |
| Properties | |
| 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 |
Decomposes |
| Solubility in water | 112 g/100 mL (20 °C) |
| Hazards | |
| Main hazards | Alkaline (chemical burns) in particular sensitive organs like eyes |
| NFPA 704 |
 0
2
0
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| R-phrases | R20/21/22, R36/37/38 |
| S-phrases | S26, S37/39 |
| 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 references |
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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.
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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".1
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 potassium compounds.
- 2KOH + CO2 → K2CO3 + H2O
Applications
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 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.citation needed It may also be used to pre-dry some ketones, alcohols, and amines prior to distillation.3
References
Bibliography
A Dictionary of Science, Oxford University Press Inc., New York 2003
External links
Wikipedia content modification information:
- This page was last modified on 1 January 2009, at 22:07.
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