Potassium carbonate
Names
IUPAC name
Potassium carbonate
Other names
Carbonate of potash, dipotassium carbonate, sub-carbonate of potash, pearl ash, potash, salt of tartar, salt of wormwood.
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.008.665
E number E501(i) (acidity regulators, ...)
RTECS number
  • TS7750000
UNII
  • InChI=1S/CH2O3.2K/c2-1(3)4;;/h(H2,2,3,4);;/q;2*+1/p-2 checkY
    Key: BWHMMNNQKKPAPP-UHFFFAOYSA-L checkY
  • InChI=1/CH2O3.2K/c2-1(3)4;;/h(H2,2,3,4);;/q;2*+1/p-2
    Key: BWHMMNNQKKPAPP-NUQVWONBAS
  • C(=O)([O-])[O-].[K+].[K+]
Properties
K
2
CO
3
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
110.3 g/100mL (20 °C)
149.2 g/100mL (100 °C)
Solubility
Acidity (pKa) 10.25
−59.0·10−6 cm3/mol
Thermochemistry[1]
114.4 J·mol−1·K−1
155.5 J·mol−1·K−1
−1151.0 kJ·mol−1
−1063.5 kJ·mol−1
Enthalpy of fusion fHfus)
27.6 kJ·mol−1
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H302, H315, H319, H335
P261, P305+P351+P338
NFPA 704 (fire diamond)
NFPA 704 four-colored diamond
2
0
0
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
1870 mg/kg (oral, rat)[2]
Safety data sheet (SDS) ICSC 1588
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 verify (what is checkY☒N ?)
Infobox references

Potassium carbonate is the inorganic compound with the formula K2CO3. It is a white salt, which is soluble in water and forms a strongly alkaline solution. It is deliquescent, often appearing as a damp or wet solid. Potassium carbonate is mainly used in the production of soap and glass.[3]

History

Potassium carbonate is the primary component of potash and the more refined pearl ash or salts of tartar. 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.[4][5]

In late 18th-century North America, before the development of baking powder, pearl ash was used as a leavening agent for quick breads.[6][7]

Production

Potassium lye (which in this case can alternatively be called potash), a substance which contains potassium carbonate, potassium bicarbonate, and potassium hydroxide,[8][9] was historically produced by dissolving the lye found in the wooden ashes inside of water for at least 24 hours, disposing of the undissolved ashes, and then drying/evaporating the remaining liquid.[8][10]

With modern observation, this process would produce greater yields if done with the ashes of banana peels due to their increased amounts of potassium carbonate.[10]

As previously mentioned, Samuel Hopkins created an improved method of making pearl ash. One of those procedures was putting the lye/potash in a kiln to remove impurities.

Potassium carbonate is today, prepared commercially, by the reaction of potassium hydroxide with carbon dioxide:[3]

2 KOH + CO2 → K2CO3 + H2O

From the solution crystallizes the sequestrate K2CO3·32H2O ("potash hydrate"). Heating this solid above 200 °C (392 °F) gives the anhydrous salt. In an alternative method, potassium chloride is treated with carbon dioxide in the presence of an organic amine to give potassium bicarbonate, which is then calcined:

2 KHCO3 → K2CO3 + H2O + CO2

Applications

References

  1. CRC handbook of chemistry and physics: a ready-reference book of chemical and physical data. William M. Haynes, David R. Lide, Thomas J. Bruno (2016-2017, 97th ed.). Boca Raton, Florida. 2016. ISBN 978-1-4987-5428-6. OCLC 930681942.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: others (link)
  2. Chambers, Michael. "ChemIDplus - 584-08-7 - BWHMMNNQKKPAPP-UHFFFAOYSA-L - Potassium carbonate [USP] - Similar structures search, synonyms, formulas, resource links, and other chemical information". chem.sis.nlm.nih.gov. Archived from the original on 2014-08-12.
  3. 1 2 H. Schultz; G. Bauer; E. Schachl; F. Hagedorn; P. Schmittinger (2005). "Potassium Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a22_039. ISBN 3-527-30673-0.
  4. "Milestones in U.S. patenting". www.uspto.gov. Retrieved 2023-08-04.
  5. "Samuel Hopkins (inventor)", Wikipedia, 2023-04-09, retrieved 2023-08-04
  6. See references to "pearl ash" in "American Cookery" by Amelia Simmons, printed by Hudson & Goodwin, Hartford, 1796.
  7. Civitello, Linda (2017). Baking powder wars: the cutthroat food fight that revolutionized cooking. Urbana, Illinois: University of Illinois Press. pp. 18–22. ISBN 978-0-252-04108-2.
  8. 1 2 "Potassium carbonate - Sciencemadness Wiki". www.sciencemadness.org. Retrieved 2023-09-08.
  9. "Lye", Wikipedia, 2023-08-08, retrieved 2023-09-08
  10. 1 2 Smith, Jess (24 April 2017). "How to Make Potassium Carbonate". sciencing.com. Retrieved 3 August 2023.
  11. Leonard, J.; Lygo, B.; Procter, G. "Advanced Practical Organic Chemistry" 1998, Stanley Thomas Publishers Ltd
  12. Child, Lydia M. "The American Frugal Housewife" 1832

Bibliography

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