Potassium acetate

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Potassium acetate
Skeletal formula of potassium acetate
Identifiers
CAS number127-08-2 YesY
PubChem31371
ChemSpider29104 N
ChEMBLCHEMBL1201058 N
ATC codeB05XA17
Jmol-3D imagesImage 1
Properties
Molecular formulaC2H3KO2
Molar mass98.14 g mol−1
AppearanceWhite deliquescent crystalline powder
Density1.8 g/cm3 (20 °C)[1]
1.57 g/cm3 (25 °C)
Melting point292 °C (558 °F; 565 K)
Boiling pointDecomposes
Solubility in water216.7 g/100 mL (0.1 °C)
233.8 g/100 mL (10 °C)
268.6 g/100 mL (25 °C)
320.8 g/100 mL (40 °C)
390.7 g/100 mL (96 °C)[2]
SolubilitySoluble in alcohol, liquid ammonia
Insoluble in ether, acetone
Solubility in methanol24.24 g/100 g (15 °C)
53.54 g/100 g (73.4 °C)[1]
Solubility in ethanol16.3 g/100 g[1]
Solubility in sulfur dioxide0.06 g/kg (0 °C)[1]
Acidity (pKa)4.76
Structure
Crystal structureMonoclinic
Thermochemistry
Specific
heat capacity
C
109.38 J/mol·K[3]
Std molar
entropy
So298
150.82 J/mol·K[3]
Std enthalpy of
formation
ΔfHo298
-722.6 kJ/mol[1]
Hazards
NFPA 704
LD503250 mg/kg (oral, rat)[4]
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references
 
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Potassium acetate
Skeletal formula of potassium acetate
Identifiers
CAS number127-08-2 YesY
PubChem31371
ChemSpider29104 N
ChEMBLCHEMBL1201058 N
ATC codeB05XA17
Jmol-3D imagesImage 1
Properties
Molecular formulaC2H3KO2
Molar mass98.14 g mol−1
AppearanceWhite deliquescent crystalline powder
Density1.8 g/cm3 (20 °C)[1]
1.57 g/cm3 (25 °C)
Melting point292 °C (558 °F; 565 K)
Boiling pointDecomposes
Solubility in water216.7 g/100 mL (0.1 °C)
233.8 g/100 mL (10 °C)
268.6 g/100 mL (25 °C)
320.8 g/100 mL (40 °C)
390.7 g/100 mL (96 °C)[2]
SolubilitySoluble in alcohol, liquid ammonia
Insoluble in ether, acetone
Solubility in methanol24.24 g/100 g (15 °C)
53.54 g/100 g (73.4 °C)[1]
Solubility in ethanol16.3 g/100 g[1]
Solubility in sulfur dioxide0.06 g/kg (0 °C)[1]
Acidity (pKa)4.76
Structure
Crystal structureMonoclinic
Thermochemistry
Specific
heat capacity
C
109.38 J/mol·K[3]
Std molar
entropy
So298
150.82 J/mol·K[3]
Std enthalpy of
formation
ΔfHo298
-722.6 kJ/mol[1]
Hazards
NFPA 704
LD503250 mg/kg (oral, rat)[4]
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Potassium acetate (CH3COOK) is the potassium salt of acetic acid.

Preparation[edit]

It can be prepared by treating a potassium-containing base such as potassium hydroxide or potassium carbonate with acetic acid:

CH3COOH + KOH → CH3COOK + H2O

This sort of reaction is known as an acid-base neutralization reaction. Sesquihydrate in water solution (CH3COOK·1½H2O) begins to form semihydrate at 41.3 °C.[2] Potassium acetate is the salt that forms along with water as acetic acid and potassium hydroxide are neutralized together.

Conditions/substances to avoid are: moisture, heat, flames, ignition sources, and strong oxidizing agents.

Applications[edit]

Potassium acetate is used as a catalyst in the production of polyurethanes.[5]

Potassium acetate can be used as a deicer instead of chloride salts such as calcium chloride or magnesium chloride. It offers the advantage of being less aggressive on soils and much less corrosive, and for this reason is preferred for airport runways. It is, however, more expensive. Potassium acetate is also the extinguishing agent used in class K fire extinguishers because of its ability to cool and form a crust over burning oils.

Food additive[edit]

Potassium acetate is used as a food additive as a preservative and acidity regulator. In the European Union, it is labeled by the E number E261;[6] it is also approved for usage in the USA[7] and Australia and New Zealand.[8] Potassium hydrogen diacetate (CAS #4251-29-0 ) with formula KH(OOCCH3)2 is a related food additive with the same E number as potassium acetate.

Medicine and biochemistry[edit]

In medicine, potassium acetate is used as part of replacement protocols in the treatment of diabetic ketoacidosis because of its ability to break down into bicarbonate and help neutralize the acidotic state.

In molecular biology, potassium acetate is used to precipitate dodecyl sulfate (DS) and DS-bound proteins, allowing the removal of proteins from DNA. It is also used as a salt for the ethanol precipitation of DNA.

Potassium acetate is used in mixtures applied for tissue preservation, fixation, and mummification. Most museums today use the formaldehyde-based method recommended by Kaiserling in 1897 which contains potassium acetate.[9] For example, Lenin's mummy was soaked in a bath containing potassium acetate.[10]

Historical[edit]

Potassium acetate was originally used in the preparation of Cadet's fuming liquid, the first organometallic compound produced. It is used as diuretic and urinary alkaliser, and acts by changing the physical properties of the body fluids and by functioning as an alkali after absortion.

References[edit]

  1. ^ a b c d e http://chemister.ru/Database/properties-en.php?dbid=1&id=504
  2. ^ a b Seidell, Atherton; Linke, William F. (1952). Solubilities of Inorganic and Organic Compounds. Van Nostrand. 
  3. ^ a b Acetic acid, potassium salt in Linstrom, P.J.; Mallard, W.G. (eds.) NIST Chemistry WebBook, NIST Standard Reference Database Number 69. National Institute of Standards and Technology, Gaithersburg MD. http://webbook.nist.gov (retrieved 2014-05-18)
  4. ^ http://chem.sis.nlm.nih.gov/chemidplus/rn/127-08-2
  5. ^ Hosea Cheung, Robin S. Tanke, G. Paul Torrence "Acetic Acid" in Ullmann's Encyclopedia of Industrial Chemistry 2005 Wiley-VCH, Weinheim. doi:10.1002/14356007.a01_045.
  6. ^ UK Food Standards Agency: "Current EU approved additives and their E Numbers". Retrieved 2011-10-27. 
  7. ^ US Food and Drug Administration: "Listing of Food Additives Status Part II". Retrieved 2011-10-27. 
  8. ^ Australia New Zealand Food Standards Code"Standard 1.2.4 - Labelling of ingredients". Retrieved 2011-10-27. 
  9. ^ Dale Ulmer, "Fixation. The Key to Good Tissue Preservation.", Journal of the International Society for Plastination, Vol 8 (1): 7-10, 1994
  10. ^ Andrew Nagorski, The Greatest Battle, Simon and Schuster, 2007, page 53.

External links[edit]