Potassium oxide



Potassium oxide
IUPAC name Potassium oxide
Other names Potassium monoxide
Identifiers
CAS number 12136-45-7
Properties
Molecular formula K2O
Molar mass 94.196 g/mol
Appearance gray crystalline solid
Density 2.35 g/cm3
Melting point

350 °C decomp. in K2O2 and K

Boiling point

n/a

Solubility in water Decomposes violently,
forming KOH
Related Compounds
Other anions Potassium superoxide
Potassium peroxide
Other cations Lithium oxide
Sodium oxide
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

Potassium oxide is a vacuum distilled at high temperatures to separate it from the potassium oxide. The two most common synthesis methods are outlined below.

  1. 4O2 (dry air) → 2K2O
  2. 2O2

Potassium oxide is a very basic oxide and reacts with water violently to produce the caustic potassium hydroxide. It is deliquescent in air and will absorb water from the atmosphere, initiating this vigorous reaction. It is therefore both toxic and corrosive to human tissue.

Metallic oxygen in a vacuum. Potassium oxide is the main by-product of this reaction.

The chemical formula K2O is used in the N-P-K (nitrogen-phosphorus-potassium) numbers on the labels of potassium rating, based on potassium oxide, would be only 19%.

References

Lange's Handbook of Chemistry (14th Edition), McGraw-Hill, 1992; Section 1; Table 1.15
The Condensed Chemical Dictionary (10th Edition), Gesner G. Hawley
Handbook of Preparative Inorganic Chemistry: Volume 1 (2nd Edition), Georg Brauer, 1963
http://scifun.chem.wisc.edu/CHEMWEEK/AgriFert/agrifert.html
http://www.inchem.org/documents/icsc/icsc/eics0769.htm
http://www.webelements.com/webelements/compounds/text/K/K2O1-12136457.html
 
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