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]

A fire extinguisher containing potassium bicarbonate
Not to be confused with Sodium bicarbonate.
Potassium bicarbonate
Names
IUPAC name
potassium hydrogen carbonate
Other names
potassium acid carbonate
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.005.509
EC Number
  • 206-059-0
E number E501(ii) (acidity regulators, ...)
UNII
Properties
KHCO3
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]

Thermochemistry
Std enthalpy of
formation (ΔfH⦵298)
 -963.2 kJ/mol
Pharmacology
A12BA04 (WHO)
Hazards
Safety data sheet MSDS
R-phrases (outdated) R36 R37 R38
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
0
1
0
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.

Uses

Food and drink

This compound is a source of carbon dioxide for leavening in baking. It can substitute for baking soda (sodium bicarbonate) for those with a low-sodium diet,[3] and it is an ingredient in low-sodium baking powders.[4][5]

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,[6] 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.[7]

Agriculture

Potassium bicarbonate has widespread use in crops, especially for neutralizing acidic soil.[8]

Potassium bicarbonate is an effective fungicide against powdery mildew and apple scab, allowed for use in organic farming.[9][10][11][12]

History

The word saleratus, from Latin sal æratus meaning "aerated salt", first used in the nineteenth century, refers to both potassium bicarbonate and sodium bicarbonate.[13]

References
  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. "Potassium Bicarbonate". encyclopedia.com. Cengage. Retrieved May 29, 2020.
  4. "Home cooking with less salt". harvard.edu. Harvard University. Retrieved May 29, 2020.
  5. Wilkens, Katy G. "You Have the (Baking) Power with Low-Sodium Baking Powders". agingkingcounty.org. Aging & Disability Services for Seattle & King County. Retrieved May 29, 2020.
  6. "Why Your Bottled Water Contains Four Different Ingredients". Time Magazine.
  7. "Purple-K-Powder". US Naval Research Laboratory. Retrieved 8 February 2012.
  8. "Potassium Bicarbonate Handbook" (PDF). Armand Products Company.
  9. "Use of Baking Soda as a Fungicide". Archived from the original on 2010-05-07. Retrieved 2010-02-14.
  10. "Powdery Mildew - Sustainable Gardening Australia". Archived from the original on 2016-03-03.
  11. "Organic Fruit Production in Michigan".
  12. "Efficacy of Armicarb (potassium bicarbonate) against scab and sooty blotch on apples" (PDF).
  13. "saleratus". merriam-webster.com. Merriam-Webster. Retrieved May 29, 2020.
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