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性質
KO2(71.10)．超酸化カリウム, IUPAC命名法による体系名は，二酸化(1－)カリウム(potassium dioxide)．生化学命名法では O2－ は超酸化物(superoxide)イオンとよばれるが，無機化学命名法では二酸化物(1－)イオンとよぶことを薦めている．液体アンモニアにKを溶かし，乾燥空気と－30～－50 ℃ で反応させるか，または，Kを乾燥空気中で長時間加熱すると得られる．黄色の正方晶系結晶．結晶には O2－ が存在し，O-O1.28 Å．炭化カルシウム型構造．高温では O2－ の向きが乱れ，塩化ナトリウム型構造になる．密度2.14 g cm－3．室温では空気中でも安定である．融点380 ℃．480 ℃ でK2O3と O2 に分解する．強い酸化剤で刺激により発火の危険性がある．水と反応して O2 を発生してKOHになる．常磁性(磁気モーメント2.04μB)で，室温以上では半導体となる．CuCl2存在下では，呼気中の水蒸気と反応して O2 を発生するので，容器に入れて登山用などの酸素源に用いられる．森北出版「化学辞典（第2版）
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化学的特性
light yellow powder or chunks
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使用
Reagent and intermediate.
One use of potassium superoxide,KO2, is for generating oxygen. It has the ability to absorb carbon dioxide, while giving out oxygen at the same time:
4KO2(s)+ 2CO2(g)--->2K2CO3(s)+ 3O2(g)
This property has been made use of in breathing equipment,e.g.for mountaineers, in submarines and in spacecraft.
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一般的な説明
A yellowish to white solid. Melting point 948°F. Mixtures with combustible material readily ignite by friction, heat, or contact with moisture. Prolonged exposure to fire or heat may cause vigorous decomposition of the material and rupturing of the container.
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空気と水の反応
Reacts explosively with water [Mellor 2, Supp. 3: 1631. 1963].
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反応プロフィール
Potassium superoxide is a powerful oxidizer. Forms on the surface of potassium metal, solid or molten, that is exposed to the air. Attempts to extinguish burning potassium with powdered graphite has resulted in violent explosions [Chem. Abstr. 63:424. 1965]. Highly oxidized potassium metal was dropped into a dish of ethyl alcohol, an immediate explosion shattered the dish. Potassium superoxide was considered the cause of the reaction [Health and Safety Inf. 251. 1967]. Potassium superoxide should not be added to pure organic materials (hydrocarbons), as ignition and violent explosion may occur. Oxidation of arsenic, antimony, copper, potassium, tin, or zinc proceeds with incandescence, [Mellor, 1941, Vol. 2, 493]. Interaction between the superoxide and diselenium dichloride is violent, [Mellor, 1947, Vol. 10, 897].
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危険性
Corrosive to tissue.
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健康ハザード
TOXIC; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance may cause severe injury, burns or death. Fire may produce irritating and/or toxic gases. Toxic fumes or dust may accumulate in confined areas (basement, tanks, hopper/tank cars, etc.). Runoff from fire control or dilution water may cause pollution.
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火災危険
May explode from friction, heat or contamination. These substances will accelerate burning when involved in a fire. May ignite combustibles (wood, paper, oil, clothing, etc.). Some will react explosively with hydrocarbons (fuels). Containers may explode when heated. Runoff may create fire or explosion hazard.
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安全性プロファイル
Explosive reaction
when heated with carbon, 2-aminophenol +
tetrahydrofuran (at 65°C). Forms a friction-
sensitive explosive mixture with
hydrocarbons. Violent reaction with
lselenium dichloride, ethanol, potassium-
sodium alloy. May ignite on contact with
organic compounds. Incandescent reaction
with metals (e.g., arsenic, antimony, copper,
potassium, tin, and zinc). When heated to
decomposition it emits toxic fumes of K2O.
See also PEROXIDES.
