Potassium acetate

Structural formula
General
Surname	Potassium acetate
other names	Potassium ethanoate (according to IUPAC ) E  261 POTASSIUM ACETATE ( INCI )
Molecular formula	C 2 H 3 KO 2
Brief description	colorless solid
External identifiers / databases
CAS number 127-08-2 EC number 204-822-2 ECHA InfoCard 100.004.385 PubChem 517044 ChemSpider 29104 Wikidata Q409199
properties
Molar mass	98.15 g mol −1
Physical state	firmly
density	1.57 g cm −3 (25 ° C)
Melting point	292 ° C
solubility	readily soluble in water (2560 g l −1 at 20 ° C)
safety instructions
GHS labeling of hazardous substances no GHS pictograms H and P phrases H: no H-phrases P: no P-phrases
Toxicological data	3250 mg kg −1 ( LD 50 ,  rat ,  oral )
Thermodynamic properties
ΔH f 0	−723.0 kJ / mol
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Potassium acetate , CH ₃ COOK, is the potassium salt of acetic acid .

properties

Potassium acetate forms colorless, hygroscopic crystals that dissolve very well (2560 g / l at 20 ° C) in water . The crystals have a melting point of 292 ° C and decompose from approx. 440 ° C. It is harmless to health. It occurs in three different crystal structures: one form exists from room temperature to 75 ° C, the second from 75 ° C to 155 ° C, the third form from 155 ° C to the melting point.

Lattice parameters of the various modifications of potassium acetate

Temperature range	Crystal system	a [Å]	b [Å]	c [Å]	β
up to 75 ° C	monoclinic	18.21	23.30	4.05	100.8 °
75 ° C to 155 ° C	monoclinic	9.31	5.82	4.03	99.2 °
above 155 ° C	orthorhombic	9.74	5.76	3.99	-

use

Potassium acetate is a food additive (E261) and is used to regulate acidity, i.e. H. the setting of the pH value (buffer function). That is why it is used as a preservative and acidifier and is mainly used in household vinegar (5 to 10) and vinegar essence (25 to 80, synthetic vinegar). Highly pure potassium acetate is also used as a starting component for the manufacture of drugs, e.g. B. for penicillin G potassium. Potassium acetate is also given to treat potassium deficiency . Because of its hygroscopic effect, it is used as a moisture-removing agent. In aviation, potassium acetate is also used as a biodegradable agent for de-icing surfaces at airports .

Manufacturing

Potassium acetate can be produced from potassium hydroxide and acetic acid by the salt formation reaction .

${\displaystyle {\ce {KOH + CH3COOH -> CH3COOK + H2O}}}$

The synthesis from potassium carbonate and acetic acid with the evolution of carbon dioxide is also possible.

${\displaystyle {\ce {K2CO3 + 2CH3COOH -> 2CH3COOK + CO2 ^ + H2O}}}$

Individual evidence

1. ↑ Entry on E 261: Potassium acetates in the European database on food additives, accessed on June 27, 2020.
2. ↑ Entry on POTASSIUM ACETATE in the CosIng database of the EU Commission, accessed on February 25, 2020.
3. ↑ ^{a b c d e f} Entry on potassium acetate in the GESTIS substance database of the IFA , accessed on December 19, 2019 (JavaScript required)
4. ↑ Entry on Potassium acetate in the ChemIDplus database of the United States National Library of Medicine (NLM), accessed on July 31, 2018 or earlier.
5. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-22.
6. ↑ ^{a b} J. Hatibarua, GS Parry: "A crystallographic study of the acetates of potassium, rubidium and cesium" in Acta Cryst. 1972 , B28 , p. 3099; doi : 10.1107 / S0567740872007496 .