![]() Potassium cations, K+ Superoxide anions, O−2 | |
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Names | |
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IUPAC name Potassium superoxide | |
Identifiers | |
3D model (JSmol) | |
ChemSpider | |
ECHA InfoCard | 100.031.574 |
EC Number |
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PubChem CID | |
RTECS number |
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UN number | 2466 |
CompTox Dashboard (EPA) | |
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Properties | |
KO2 | |
Molar mass | 71.096 g·mol−1 |
Appearance | yellow 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] |
Std enthalpy of formation (ΔfH⦵298) | −283 kJ/mol [4] |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards | Corrosive, oxidizer, reacts violently with water |
GHS labelling: [5] | |
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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) | |
Related compounds | |
Other cations | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
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.
Potassium superoxide is produced by burning molten potassium in an atmosphere of excess oxygen. [7]
The salt consists of K+ and O−2 ions, linked by ionic bonding. The O–O distance is 1.28 Å. [2]
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:
It reacts with carbon dioxide, releasing oxygen:
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]
The Russian Space Agency has successfully used potassium superoxide in chemical oxygen generators for its spacesuits and Soyuz spacecraft. Potassium superoxide was also used in a rudimentary life support system for five mice as part of the Biological Cosmic Ray Experiment on Apollo 17. [12]
KO2 has also been used in canisters for rebreathers for firefighting and mine rescue, and in cartridges for chemical oxygen generators on submarines. A flash fire caused by dropping such a cartridge into seawater contributed to the Kursk disaster. This highly exothermic reaction with water is also the reason why potassium superoxide has had limited use in scuba rebreathers.
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".
Potassium chlorate is the inorganic compound with the molecular formula KClO3. In its pure form, it is a white solid. After sodium chlorate, it is the second most common chlorate in industrial use. It is a strong oxidizing agent and its most important application is in safety matches. In other applications it is mostly obsolete and has been replaced by safer alternatives in recent decades. It has been used
Sodium percarbonate or sodium carbonate peroxide is a chemical substance with empirical 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.
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:
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.
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.
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).
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.
Hexamethylphosphoramide, often abbreviated HMPA, is a phosphoramide (an amide of phosphoric acid) with the formula [(CH3)2N]3PO. This colorless liquid is used as a solvent in organic synthesis.
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).
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.
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.
Iron(III) nitrate, or ferric nitrate, is the name used for a series of inorganic compounds with the formula Fe(NO3)3.(H2O)n. Most common is the nonahydrate Fe(NO3)3.(H2O)9. The hydrates are all pale colored, water-soluble paramagnetic salts.
In chemistry, a molybdate is a compound containing an oxyanion with molybdenum in its highest oxidation state of +6: O−−Mo(=O)2−O−. Molybdenum can form a very large range of such oxyanions, which can be discrete structures or polymeric extended structures, although the latter are only found in the solid state. The larger oxyanions are members of group of compounds termed polyoxometalates, and because they contain only one type of metal atom are often called isopolymetalates. The discrete molybdenum oxyanions range in size from the simplest MoO2−
4, found in potassium molybdate up to extremely large structures found in isopoly-molybdenum blues that contain for example 154 Mo atoms. The behaviour of molybdenum is different from the other elements in group 6. Chromium only forms the chromates, CrO2−
4, Cr
2O2−
7, Cr
3O2−
10 and Cr
4O2−
13 ions which are all based on tetrahedral chromium. Tungsten is similar to molybdenum and forms many tungstates containing 6 coordinate tungsten.
The purpose of a mineralizer is to facilitate the transport of insoluble “nutrient” to a seed crystal by means of a reversible chemical reaction. Over time, the seed crystal accumulates the material that was once in the nutrient and grows. Mineralizers are additives that aid the solubilization of the nutrient solid. When used in small quantities, mineralizers function as catalysts. Typically, a more stable solid is crystallized from a solution that consists of a less stable solid and a solvent. The process is done by dissolution-precipitation or crystallization process.
Methods of oxygen storage for subsequent use span many approaches, including high pressures in oxygen tanks, cryogenics, oxygen-rich compounds and reaction mixtures, and chemical compounds that reversibly release oxygen upon heating or pressure change. O2 is the second most important industrial gas.