Potassium bicarbonate

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Potassium bicarbonate
Potassium bicarbonate
Hydrogenuhličitan draselný.JPG
Identifiers
CAS number 298-14-6 YesY
PubChem 516893
ChemSpider 55053 YesY
EC number 206-059-0
ATC code A12BA04
Jmol-3D images Image 1
Properties
Molecular formula 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)
Solubility in water 33.7 g/100 mL (20 °C)
60 g/100 mL (60 °C)
Solubility practically insoluble in alcohol
Acidity (pKa) 10.329[1]

6.351 (carbonic acid)[1]

Thermochemistry
Std enthalpy of
formation
ΔfHo298
-963.2 kJ/mol
Hazards
MSDS MSDS
EU Index Not listed
R-phrases R36 R37 R38
NFPA 704
Flammability (red): no hazard code Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity (yellow): no hazard code Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point Non-Flammable
LD50 > 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 noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

Potassium bicarbonate (also known as potassium hydrogen carbonate or potassium acid carbonate) is a colorless, odorless, slightly basic, salty substance. According to the US Food and Drug Administration (FDA), potassium bicarbonate is "generally recognized as safe".[2] There is no evidence of human carcinogenicity, no adverse effects of overexposure, and an undetermined LD50. Physically, potassium bicarbonate occurs as a crystal or a soft white granular powder. Potassium bicarbonate is very rarely found in its natural form, the mineral called kalicinite.

A fire extinguisher containing potassium bicarbonate.

Chemistry[edit]

Decomposition of the bicarbonate occurs between 100 °C and 120 °C:

2 KHCO3 → K2CO3 + CO2 + H2O

It is manufactured by reversing the above: reaction of potassium carbonate with carbon dioxide and water.

K2CO3 + CO2 + H2O → 2 KHCO3

Uses[edit]

The compound is used as a source of carbon dioxide for leavening in baking, extinguishing fire in dry chemical fire extinguishers, acting as a reagent, and a strong buffering agent in medications.

It is used as an additive in winemaking and as a base in foods and to regulate pH. It is a common ingredient in club soda, where it is used to soften the effect of effervescence.

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 National Fire Protection Association for firefighting at airport crash rescue sites. It is about twice as effective in fire suppression as sodium bicarbonate.[3]

Potassium bicarbonate is an effective fungicide against powdery mildew and apple scab, allowed for use in organic farming.[4][5] [6][7]

Potassium bicarbonate is often found added to bottled water to affect taste.[citation needed]

Potassium bicarbonate has widespread use in crops, especially for neutralizing acidic soil[citation needed]

History[edit]

The word saleratus, from Latin sal æratus meaning "aerated salt", was widely used in the 19th century for both potassium bicarbonate and sodium bicarbonate. The term has now fallen out of common usage.

References[edit]

  1. ^ a b Goldberg, Robert N.; Kishore, Nand; Lennen, Rebecca M. (2003). "Thermodynamic quantities for the ionization reactions of buffers in water". In David R. Lide. 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. 
  2. ^ GRAS Notification Program (October 31, 2006). "Potassium bicarbonate". GRAS Substances (SCOGS) Database. US FDA. Archived from the original on March 5, 2011. Retrieved March 5, 2011. 
  3. ^ "Purple-K-Powder". US Naval Research Laboratory. Retrieved 8 February 2012. 
  4. ^ http://attra.ncat.org/attra-pub/bakingsoda.html
  5. ^ Powdery Mildew - Sustainable Gardening Australia
  6. ^ Organic Fruit Production in Michigan
  7. ^ [1]

External links[edit]