Potassium superoxide

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Potassium superoxide
Potassium-superoxide-unit-cell-3D-ionic.png
  Potassium cations, K+
  Superoxide anions, O−2
Potassium superoxide powder.png
Names
IUPAC name
Potassium superoxide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.031.574 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 234-746-5
PubChem CID
RTECS number
  • TT6053000
UN number 2466
  • InChI=1S/2K.O2/c;;1-2/q2*+1;-2 X mark.svgN
    Key: XXQBEVHPUKOQEO-UHFFFAOYSA-N X mark.svgN
  • InChI=1/2K.O2/c;;1-2/q2*+1;-2
    Key: XXQBEVHPUKOQEO-UHFFFAOYAV
  • [K+].[O-]=O
Properties
KO2
Molar mass 71.096 g·mol−1
Appearanceyellow solid
Density 2.14 g/cm3, solid
Melting point 560 °C (1,040 °F; 833 K) (decomposes)
Hydrolysis
+3230·10−6 cm3/mol [1]
Structure
Body-centered tetragonal [2] [3]
Thermochemistry
Std molar
entropy (S⦵298)
117 J/(mol·K) [4]
−283 kJ/mol [4]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Corrosive, oxidizer, reacts violently with water
GHS labelling: [5]
GHS-pictogram-rondflam.svg GHS-pictogram-acid.svg
Danger
H271, H314
P210, P220, P221, P260, P264, P280, P283, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P306+P360, P310, P321, P363, P370+P378, P371+P380+P375, P405, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazard W+OX: Reacts with water in an unusual or dangerous manner AND is oxidizer
3
0
3
W
OX
Related compounds
Other cations
Related potassium oxides
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Potassium superoxide is an inorganic compound with the formula K O 2. [6] 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 CO2 scrubber, H2O dehumidifier, and O2 generator in rebreathers, spacecraft, submarines, and spacesuits.

Contents

Production and reactions

Potassium superoxide is produced by burning molten potassium in an atmosphere of excess oxygen. [7]

K + O2 → KO2

The salt consists of K+ and O−2 ions, linked by ionic bonding. The O–O distance is 1.28 Å. [2]

Reactivity

Potassium superoxide is a source of superoxide, which is an oxidant and a nucleophile, depending on its reaction partner. [8]

Upon contact with water, it undergoes disproportionation to potassium hydroxide, oxygen, and hydrogen peroxide:

4 KO2 + 2 H2O → 4 KOH + 3 O2
2 KO2 + 2 H2O → 2 KOH + H2O2 + O2 [9]

It reacts with carbon dioxide, releasing oxygen:

4 KO2 + 2 CO2 → 2 K2CO3 + 3 O2
4 KO2 + 4 CO2 + 2 H2O → 4 KHCO3 + 3 O2

Theoretically, 1 kg of KO2 absorbs 0.310 kg of CO2 while releasing 0.338 kg of O2. One mole of KO2 absorbs 0.5 moles of CO2 and releases 0.75 moles of oxygen.

Potassium superoxide finds only niche uses as a laboratory reagent. Because it reacts with water, KO2 is often studied in organic solvents. Since the salt is poorly soluble in nonpolar solvents, crown ethers 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. [10]

Ion exchange with tetramethylammonium hydroxide gives tetramethylammonium superoxide, a yellow solid. [11]

Applications

The Russian Space Agency has had success using potassium superoxide in chemical oxygen generators for its spacesuits and Soyuz spacecraft. KO2 has also been used in canisters for rebreathers for fire fighting and mine rescue work, but had limited use in scuba rebreathers because of its highly exothermic reaction with water. Potassium superoxide was used in a rudimentary life support system for five mice as part of the Biological Cosmic Ray Experiment on Apollo 17. [12]

Related Research Articles

<span class="mw-page-title-main">Oxide</span> Chemical compound where oxygen atoms are combined with atoms of other elements

An oxide is a chemical compound containing at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– ion with oxygen in the oxidation state of −2. Most of the Earth's crust consists of oxides. Even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a thin skin of Al2O3 that protects the foil from further oxidation.

In chemistry, a superoxide is a compound that contains the superoxide ion, which has the chemical formula O−2. The systematic name of the anion is dioxide(1−). The reactive oxygen ion superoxide is particularly important as the product of the one-electron reduction of dioxygen O2, which occurs widely in nature. Molecular oxygen (dioxygen) is a diradical containing two unpaired electrons, and superoxide results from the addition of an electron which fills one of the two degenerate molecular orbitals, leaving a charged ionic species with a single unpaired electron and a net negative charge of −1. Both dioxygen and the superoxide anion are free radicals that exhibit paramagnetism. Superoxide was historically also known as "hyperoxide".

<span class="mw-page-title-main">Sodium percarbonate</span> Chemical compound

Sodium percarbonate or sodium carbonate peroxide is a chemical substance with formula Na2H3CO6. It is an adduct of sodium carbonate and hydrogen peroxide whose formula is more properly written as 2 Na2CO3 · 3 H2O2. It is a colorless, crystalline, hygroscopic and water-soluble solid. It is sometimes abbreviated as SPC. It contains 32.5% by weight of hydrogen peroxide.

<span class="mw-page-title-main">Hypochlorite</span> Anion

In chemistry, hypochlorite, or chloroxide is an anion with the chemical formula ClO−. It combines with a number of cations to form hypochlorite salts. Common examples include sodium hypochlorite and calcium hypochlorite. The Cl-O distance in ClO− is 1.69 Å.

Cuprates are a class of compounds that contain copper (Cu) atom(s) in an anion. They can be broadly categorized into two main types:

<span class="mw-page-title-main">Potassium ferrate</span> Chemical compound

Potassium ferrate is an inorganic compound with the formula K2FeO4. It is the potassium salt of ferric acid. Potassium ferrate is a powerful oxidizing agent with applications in green chemistry, organic synthesis, and cathode technology.

<span class="mw-page-title-main">Sodium peroxide</span> Chemical compound

Sodium peroxide is an inorganic compound with the formula Na2O2. This yellowish solid is the product of sodium ignited in excess oxygen. It is a strong base. This metal peroxide exists in several hydrates and peroxyhydrates including Na2O2·2H2O2·4H2O, Na2O2·2H2O, Na2O2·2H2O2, and Na2O2·8H2O. The octahydrate, which is simple to prepare, is white, in contrast to the anhydrous material.

<span class="mw-page-title-main">Sodium superoxide</span> Chemical compound

Sodium superoxide is the inorganic compound with the formula NaO2. This yellow-orange solid is a salt of the superoxide anion. It is an intermediate in the oxidation of sodium by oxygen.

<span class="mw-page-title-main">Sodium periodate</span> Chemical compound

Sodium periodate is an inorganic salt, composed of a sodium cation and the periodate anion. It may also be regarded as the sodium salt of periodic acid. Like many periodates, it can exist in two different forms: sodium metaperiodate (formula‍ NaIO4) and sodium orthoperiodate (normally Na2H3IO6, but sometimes the fully reacted salt Na5IO6). Both salts are useful oxidising agents.

<span class="mw-page-title-main">Ozonide</span> Polyatomic ion (O3, charge –1), or cyclic compounds made from ozone and alkenes

Ozonide is the polyatomic anion O−3. Cyclic organic compounds formed by the addition of ozone to an alkene are also called ozonides.

The nitrosonium ion is NO+, in which the nitrogen atom is bonded to an oxygen atom with a bond order of 3, and the overall diatomic species bears a positive charge. It can be viewed as nitric oxide with one electron removed. This ion is usually obtained as the following salts: NOClO4, NOSO4H (nitrosylsulfuric acid, more descriptively written ONSO3OH) and NOBF4. The ClO−4 and BF−4 salts are slightly soluble in acetonitrile CH3CN. NOBF4 can be purified by sublimation at 200–250 °C and 0.01 mmHg (1.3 Pa).

<span class="mw-page-title-main">Potassium manganate</span> Chemical compound

Potassium manganate is the inorganic compound with the formula K2MnO4. This green-colored salt is an intermediate in the industrial synthesis of potassium permanganate, a common chemical. Occasionally, potassium manganate and potassium permanganate are confused, but each compound's properties are distinct.

<span class="mw-page-title-main">Cobalt(III) fluoride</span> Chemical compound

Cobalt(III) fluoride is the inorganic compound with the formula CoF3. Hydrates are also known. The anhydrous compound is a hygroscopic brown solid. It is used to synthesize organofluorine compounds.

<span class="mw-page-title-main">Silver carbonate</span> Chemical compound

Silver carbonate is the chemical compound with the formula Ag2CO3. This salt is yellow but typical samples are grayish due to the presence of elemental silver. It is poorly soluble in water, like most transition metal carbonates.

Potassium hypomanganate is the inorganic compound with the formula K3MnO4. Also known as potassium manganate(V), this bright blue solid is a rare example of a salt with the hypomanganate or manganate(V) anion, where the manganese atom is in the +5 oxidation state. It is an intermediate in the production of potassium permanganate and the industrially most important Mn(V) compound.

<span class="mw-page-title-main">Lithium peroxide</span> Chemical compound

Lithium peroxide is the inorganic compound with the formula Li2O2. Lithium peroxide is a white solid, and unlike most other alkali metal peroxides, it is nonhygroscopic. Because of its high oxygen:mass and oxygen:volume ratios, the solid has been used to remove CO2 from and release O2 to the atmosphere in spacecraft.

<span class="mw-page-title-main">Nickel oxide hydroxide</span> Chemical compound

Nickel oxide hydroxide is the inorganic compound with the chemical formula NiO(OH). It is a black solid that is insoluble in all solvents but attacked by base and acid. It is a component of the nickel–metal hydride battery and of the nickel–iron battery.

<span class="mw-page-title-main">Carbon dioxide scrubber</span> Device which absorbs carbon dioxide from circulated gas

A carbon dioxide scrubber is a piece of equipment that absorbs carbon dioxide (CO2). It is used to treat exhaust gases from industrial plants or from exhaled air in life support systems such as rebreathers or in spacecraft, submersible craft or airtight chambers. Carbon dioxide scrubbers are also used in controlled atmosphere (CA) storage and carbon capture and storage processes.

<span class="mw-page-title-main">Metal peroxide</span> Metal-containing compounds with peroxide (O2) ions/groups

In chemistry, metal peroxides are metal-containing compounds with ionically- or covalently-bonded peroxide groups. This large family of compounds can be divided into ionic and covalent peroxide. The first class mostly contains the peroxides of the alkali and alkaline earth metals whereas the covalent peroxides are represented by such compounds as hydrogen peroxide and peroxymonosulfuric acid. In contrast to the purely ionic character of alkali metal peroxides, peroxides of transition metals have a more covalent character.

References

  1. ↑ "Handbook of Chemistry and Physics 102nd Edition". CRC Press.
  2. 1 2 Abrahams, S. C.; Kalnajs, J. (1955). "The Crystal Structure of α-Potassium Superoxide". Acta Crystallographica. 8 (8): 503–6. doi: 10.1107/S0365110X55001540 .
  3. ↑ "Information card for entry 2310803". Crystallography Open Database . Retrieved 28 July 2022.
  4. 1 2 Zumdahl, Steven S. (2009). Chemical Principles (6th ed.). Houghton Mifflin. p. A22. ISBN   978-0-618-94690-7.
  5. ↑ "Potassium superoxide". pubchem.ncbi.nlm.nih.gov. Retrieved 14 December 2021.
  6. ↑ Hayyan M.; Hashim M. A.; AlNashef I. M. (2016). "Superoxide Ion: Generation and Chemical Implications". Chem. Rev. 116 (5): 3029–3085. doi: 10.1021/acs.chemrev.5b00407 . PMID   26875845.
  7. ↑ Jakob, Harald; Leininger, Stefan; Lehmann, Thomas; Jacobi, Sylvia; Gutewort, Sven (2007). "Peroxo Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH. doi:10.1002/14356007.a19_177.pub2. ISBN   978-3527306732.
  8. ↑ Johnson, Roy A.; Adrio, Javier; Ribagorda, María (2007). "Potassium Superoxide". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rp250.pub2. ISBN   978-0471936237.
  9. ↑ Kumar De, Anil (2007). A Text Book of Inorganic Chemistry. New Age International. p. 247. ISBN   978-8122413847.
  10. ↑ Johnson, Roy A.; Adrio, Javier; Ribagorda, María (2001). "Potassium Superoxide". e-EROS Encyclopedia of Reagents for Organic Synthesis. Wiley. doi:10.1002/047084289X.rp250.pub2. ISBN   0471936235.
  11. ↑ Bohle, D. Scott; Sagan, Elisabeth S. (2004). Tetramethylammonium Salts of Superoxide and Peroxynitrite. Inorganic Syntheses. p. 36. doi:10.1002/0471653683.ch1.
  12. ↑ Haymaker, Webb; Look, Bonne C.; Benton, Eugene V.; Richard C. Simmonds (1975-01-01). "The Apollo 17 pocket mouse experiment (Biocore)". Biomedical Results of Apollo. NASA-SP-368.
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