Potassium oxide ( K O) is an ionic compound of

potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...

and

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

. It is a base. This pale yellow solid is the simplest oxide of potassium. It is a highly reactive compound that is rarely encountered. Some industrial materials, such as fertilizers and cements, are assayed assuming the percent composition that would be equivalent to K₂O.

Production

Potassium oxide is produced from the reaction of oxygen and potassium; this reaction affords

potassium peroxide Potassium peroxide is an inorganic compound with the molecular formula K2O2. It is formed as potassium reacts with oxygen in the air, along with potassium oxide (K2O) and potassium superoxide (KO2). Potassium peroxide reacts with water to for ...

, K₂O₂. Treatment of the peroxide with potassium produces the oxide: : Alternatively and more conveniently, K₂O is synthesized by heating potassium nitrate with metallic potassium: : Other possibility is to heat potassium peroxide at 500 °C which decomposes at that temperature giving pure potassium oxide and oxygen. :

Potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utili ...

cannot be further dehydrated to the oxide but it can react with molten potassium to produce it, releasing

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

as a byproduct. :

Properties and reactions

K₂O crystallises in the antifluorite structure. In this motif the positions of the

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

s and

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

s are reversed relative to their positions in CaF₂, with potassium ions coordinated to 4 oxide ions and oxide ions coordinated to 8 potassium.Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. . K₂O is a basic oxide and reacts with water violently to produce the caustic

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utili ...

. It is

deliquescent Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption (chemistry), absorption or adsorption from the surrounding Natural environment, environment, which is usually at normal or room temperature. If water mol ...

and will absorb water from the atmosphere, initiating this vigorous reaction.

Term use in industry

The chemical formula K₂O (or simply 'K') is used in several industrial contexts: the N-P-K numbers for fertilizers, in cement formulas, and in glassmaking formulas. Potassium oxide is often not used directly in these products, but the amount of potassium is reported in terms of the K₂O equivalent for whatever type of

potash Potash ( ) includes various mined and manufactured salts that contain potassium in water- soluble form.

was used, such as potassium carbonate. For example, potassium oxide is about 83%

by weight, while potassium chloride is only 52%. Potassium chloride provides less

than an equal amount of potassium oxide. Thus, if a fertilizer is 30% potassium chloride by weight, its standard

rating, based on potassium oxide, would be only 18.8%.

References

External links

{{Oxides Oxides Potassium compounds Deliquescent materials Fluorite crystal structure