Potassium superoxide is an
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemi ...
with the formula KO
2. It is a yellow
paramagnetic solid that decomposes in moist air. It is a rare example of a stable salt of the
superoxide anion. It is used as a scrubber, dehumidifier, and generator in
rebreather
A rebreather is a breathing apparatus that absorbs the carbon dioxide of a user's exhaled breath to permit the rebreathing (recycling) of the substantially unused oxygen content, and unused inert content when present, of each breath. Oxygen is ...
s,
spacecraft
A spacecraft is a vehicle or machine designed to spaceflight, fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including Telecommunications, communications, Earth observation satellite, Earth ...
,
submarines, and
spacesuits.
Production and reactions
Potassium superoxide is produced by burning molten potassium in an atmosphere of excess
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as we ...
.
:K + →
The salt consists of and ions, linked by ionic bonding. The O−O distance is 1.28 Å.
Reactivity
Potassium superoxide is a source of superoxide, which is a reductant and a nucleophile, depending on its reaction partner.
Upon contact with water, it undergoes
disproportionation
In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term ca ...
to
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 expl ...
, oxygen, and hydrogen peroxide:
:2 + → 2 KOH +
: + → KOH + +
It reacts with carbon dioxide, releasing oxygen:
:2 + → K
2CO
3 +
:2 + 2 + H
2O → 2 KHCO
3 +
Potassium superoxide finds only niche uses as a laboratory reagent. Because it reacts with water, is often studied in organic solvents. Since the salt is poorly soluble in nonpolar solvents,
crown ether
In organic chemistry, crown ethers are cyclic chemical compounds that consist of a ring containing several ether groups (). The most common crown ethers are cyclic oligomers of ethylene oxide, the repeating unit being ethyleneoxy, i.e., . I ...
s are typically used. The
tetraethylammonium salt is also known. Representative reactions of these salts involve using superoxide as a
nucleophile, e.g., in converting alkyl bromides to alcohols and acyl chlorides to
diacyl peroxides.
Ion exchange with
tetramethylammonium hydroxide gives tetramethylammonium superoxide, a yellow solid.
Applications
The
Russian Space Agency has had success using potassium superoxide in
chemical oxygen generators for its spacesuits and
Soyuz spacecraft. has also been used in canisters for rebreathers for
fire fighting and
mine rescue work, but had limited use in
scuba
Scuba may refer to:
* Scuba diving
** Scuba set, the equipment used for scuba (Self-Contained Underwater Breathing Apparatus) diving
* Scuba, an in-memory database developed by Facebook
* Submillimetre Common-User Bolometer Array Two instruments ...
rebreathers because of its highly exothermic reaction with water.
Theoretically, 1 kg of absorbs 0.310 kg of while releasing 0.338 kg of . One mole of absorbs 0.5 moles of and releases 0.75 moles of oxygen.
References
{{oxygen compounds
Potassium compounds
Superoxides
Oxidizing agents