Potassium bicarbonate

Potassium bicarbonate (also known as potassium hydrogen carbonate or potassium acid carbonate) is the inorganic compound with the chemical formula KHCO3. It is a white solid.[1]

Potassium bicarbonate
IUPAC name
potassium hydrogen carbonate
Other names
potassium acid carbonate
3D model (JSmol)
ECHA InfoCard 100.005.509
EC Number
  • 206-059-0
E number E501(ii) (acidity regulators, ...)
Molar mass 100.115 g/mol
Appearance white crystals
Odor odorless
Density 2.17 g/cm3
Melting point 292 °C (558 °F; 565 K) (decomposes)
22.4 g/100 mL (20 °C)[1]
Solubility practically insoluble in alcohol
Acidity (pKa) 10.329[2]

6.351 (carbonic acid)[2]

-963.2 kJ/mol
A12BA04 (WHO)
Safety data sheet MSDS
R-phrases (outdated) R36 R37 R38
NFPA 704 (fire diamond)
Flash point Non-Flammable
Lethal dose or concentration (LD, LC):
> 2000 mg/kg (rat, oral)
Related compounds
Other anions
Potassium carbonate
Other cations
Sodium bicarbonate
Ammonium bicarbonate
Related compounds
Potassium bisulfate
Potassium hydrogen phosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Production and reactivity

It is manufactured by treating an aqueous solution of potassium carbonate with carbon dioxide:[1]

K2CO3 + CO2 + H2O 2 KHCO3

Decomposition of the bicarbonate occurs between 100 and 120 °C (212 and 248 °F):

2 KHCO3 K2CO3 + CO2 + H2O

This reaction is employed to prepare high purity potassium carbonate.


This compound is a source of carbon dioxide for leavening in baking, and for extinguishing fire in dry chemical fire extinguishers.

Acidity regulator

As an inexpensive, nontoxic base, it is widely used in diverse application to regulate pH or as a reagent. Examples include as buffering agent in medications, an additive in winemaking.

Potassium bicarbonate is often found added to club soda to improve taste,[3] and to soften the effect of effervescence.

Fire extinguishers

Potassium bicarbonate is used as a fire suppression agent ("BC dry chemical") in some dry chemical fire extinguishers, as the principal component of the Purple-K dry chemical, and in some applications of condensed aerosol fire suppression. It is the only dry chemical fire suppression agent recognized by the U.S. National Fire Protection Association for firefighting at airport crash rescue sites. It is about twice as effective in fire suppression as sodium bicarbonate.[4]


Potassium bicarbonate has widespread use in crops, especially for neutralizing acidic soil.[5]

Potassium bicarbonate is an effective fungicide against powdery mildew and apple scab, allowed for use in organic farming.[6][7][8][9]


The word saleratus, from Latin sal æratus meaning "aerated salt", was widely used in the nineteenth century for both potassium bicarbonate and sodium bicarbonate. The term has now fallen out of common usage.


  1. 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.CS1 maint: uses authors parameter (link)
  2. Goldberg, Robert N.; Kishore, Nand; Lennen, Rebecca M. (2003). "Thermodynamic quantities for the ionization reactions of buffers in water". In David R. Lide (ed.). CRC handbook of chemistry and physics (84th ed.). Boca Raton, FL: CRC Press. pp. 7–13. ISBN 978-0-8493-0595-5. Retrieved 6 March 2011.
  3. "Why Your Bottled Water Contains Four Different Ingredients". Time Magazine.
  4. "Purple-K-Powder". US Naval Research Laboratory. Retrieved 8 February 2012.
  5. "Potassium Bicarbonate Handbook" (PDF). Armand Products Company.
  6. "Use of Baking Soda as a Fungicide".
  7. "Powdery Mildew - Sustainable Gardening Australia". Archived from the original on 2016-03-03.
  8. "Organic Fruit Production in Michigan".
  9. "Efficacy of Armicarb (potassium bicarbonate) against scab and sooty blotch on apples" (PDF).
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