窒素

歴史

古くから元素と考えられていた空気が、元素ではないということが明らかにされてきた18世紀、イギリスのD・ラザフォードは1772年、木炭やろうそくを瓶の中で燃やしたとき固定空気（二酸化炭素）ができること、これを除いても、なおあとに気体が残り、この気体が空気と違って燃焼を支持しないことを知り、有毒気体noxious airとよび、フロギストンの飽和した気体であるとした。1789年フランスのラボアジエは、フロギストンを否定するとともに空気から酸素を除いた気体の中では呼吸ができないことから、否定を意味するaと、生命を保持することを意味するzotikosとによってazoteとした。そのドイツ語訳がstickstoff（息が詰まる物質）である。日本語の窒素は文字どおりの意味（窒息）に基づいている。同じころフランスのシャプタルJean Antonie Chaptal（1756―1832）は、カ性カリの存在下、この気体と酸素を火花によって反応させると硝石の原料が得られることから、硝石を意味するラテン語nitrumと、生じるを意味するギリシア語gennaoとによってnitrogèneという名称を提案しており、これから英語のnitrogenという語が生じた。［守永健一・中原勝儼］

存在

宇宙では五番目に多い元素で、恒星のエネルギーサイクルに含まれる。宇宙空間にもN2、NH、CN、NO、NH3などの分子の存在が示されている。地球大気中の成分としてはもっとも多く、体積で約78.1％、重量では約75.5％に達する。ほかに微量のアンモニア、アンモニウム塩、さらに空中放電や自動車の排気ガスなどによって生じた窒素酸化物と硝酸塩が大気に含まれている。土壌にも1％足らず、主として硝酸塩として存在する。窒素は生物にとって必須(ひっす)の元素であり、動植物中には平均して約16％、海水にも微量の窒素が含まれている。自然界における窒素は、空気中の気体窒素をはじめとし、アンモニア、硝酸などからタンパク質、核酸にわたって、構造の簡単なものから複雑なものまで多数の化合物として存在し、生体に深い関係をもって循環している。すなわち、土壌中の簡単な窒素化合物は植物によってタンパク質その他の複雑な化合物となり、動物が植物を摂取することによって動物の構成物質となる。さらに、動植物の死骸(しがい)や排出物のタンパク質は腐敗微生物によって還元され、ふたたび植物体内に吸収される。

定義

本品は、気体の分子である。地球大気の約78%は窒素からなる。

性質

無色、無味、無臭の気体。沸点は酸素より低く、融点は高い。液体、固体でも無色。つねに二原子分子として存在する。酸素よりもやや水に溶けにくい。結晶は零下238～零下210℃では六方晶系、零下238℃以下では立方晶系で、窒素分子N2がほぼ立方最密充填(じゅうてん)構造をとっている。常温では化学的に不活発である。そのため常温で窒素と直接反応するのは金属リチウム、窒素固定酵素をもつバクテリアや少数の金属錯体だけである。燃焼を支えず、呼吸を助けないが有毒ではない。高温では他の元素と直接化合し、アンモニア、酸化窒素など多くの窒化物をつくる。放電管に窒素を通して放電すると、きわめて反応性の高い窒素が得られ、活性窒素とよんでいる。放電を止めてからも黄色の残光が短時間みられる。これは普通の窒素分子のほかに原子状の窒素が存在し、残光は窒素原子の再結合で生じる窒素分子の励起状態に起因するものである。

解説

元素記号はN。原子番号７，原子量14.00643〜14.00728。融点−209.86℃，沸点−195.8℃。非金属元素の一つ。単体は２原子分子N2で，無色，無臭の気体。水にやや溶けるが酸素よりは溶けにくい。常温では化学的に不活発で，助燃性はない。アンモニア合成の原料として重要。不活性気体中で行う金属冶金その他に用い，液体窒素は冷却剤。通常加圧ボンベに入れて30℃以下でたくわえる。大気中の最多成分（体積で約78％）であり，有機化合物として生物圏に広く存在し，海水，岩石などにも硝酸塩その他のかたちとして存在する。太陽大気，星雲中などにもかなり存在することが知られている。工業的には主として液体空気を分留して得る。→空中窒素固定→関連項目石灰窒素
株式会社平凡社 百科事典マイペディアについて　情報

用途

アンモニア?硝酸?硝酸塩?シアン化物?火薬類、等の製造。

製法

工業的には、空気を液化した液体空気から酸素とともに分留して取り出す方法が広く用いられている。実験室では、亜硝酸アンモニウム濃溶液、または塩化アンモニウムと亜硝酸ナトリウムとの混合物を約70℃に熱する。市販品は液体窒素としてタンクローリーあるいはボンベ入り（ボンベの色はねずみ色）で取り扱われる。純度99.9％で、通常の目的にはそのまま使用できる。

空気中の窒素を分離、固定し、アンモニア、硝酸をはじめとする各種の窒素化合物をつくる工業を窒素工業という。窒素の鉱物資源としては硝石およびチリ硝石NaNO3が有名であるが、19世紀の終わりごろ空中窒素固定法が発明され、これらの工業的価値は少なくなり、窒素工業は空中窒素固定工業を意味するようになった。

用途

水素と反応させてアンモニアをつくるアンモニア合成にもっとも多く用いられる。アンモニアから硝酸、肥料、染料など多くの窒素化合物がつくられる。窒素が化学的に不活性であることから、鉄鋼などの金属精錬をはじめとして化学工業、食品工業、電子工業などで酸化防止用封入ガス、電球封入ガスなどとして広く、また大量に用いられる。液体窒素は食品の急速冷凍用、土木用凍結剤、低温微粉砕用その他各種の目的に対応して安全な寒剤として広く用いられる。

化粧品の成分用途

噴射剤

効能

医療用ガス

商品名

液体窒素 (伊藤忠工業ガス); 液体窒素 (協栄高圧ガス); 液体窒素 (水島酸素商会); 液体窒素 (立川酸素); 液化窒素 (エア・ウォーター); 液化窒素 (エア・ガシズ北九州); 液化窒素 (三共酸素商会); 液化窒素 (岡谷酸素); 液化窒素 (日本エア・リキード); 液化窒素 (鹿児島酸素); 窒素 (エア・ウォーター); 窒素 (エア・ガシズ北九州); 窒素 (カンサン); 窒素 (サイサン); 窒素 (サカヰ産業); 窒素 (サツマ酸素工業); 窒素 (ゼネラルガスセンター); 窒素 (ダイオー); 窒素 (京葉帝酸); 窒素 (伊藤忠工業ガス); 窒素 (協和ガス); 窒素 (協栄高圧ガス); 窒素 (名古屋酸素); 窒素 (土佐酸素); 窒素 (大和熔材); 窒素 (大和酸素工業); 窒素 (大陽日酸); 窒素 (大陽日酸北海道); 窒素 (宇野酸素); 窒素 (富士酸素工業); 窒素 (小池酸素工業); 窒素 (山陰酸素工業); 窒素 (岩谷瓦斯); 窒素 (岩谷産業); 窒素 (市村酸素); 窒素 (新潟アイ・ジー・エス); 窒素 (日本エア・リキード); 窒素 (東三河総合ガスセンター); 窒素 (東京高圧山崎); 窒素 (東日本メディカルガス); 窒素 (東洋高圧ガス); 窒素 (東邦アセチレン); 窒素 (東邦酸素工業); 窒素 (東邦酸素工業); 窒素 (松山酸素); 窒素 (沼津酸素工業); 窒素 (浪速酸素); 窒素 (熊本酸素); 窒素 (百一酸素); 窒素 (福岡酸素); 窒素 (立川酸素); 窒素 (舞鶴大同ガス); 窒素 (高圧ガス工業); 窒素 (高松帝酸); 窒素 (鹿児島熔材); 窒素 (鹿児島酸素); 窒素ガス (オカノ)

説明

Nitrogen makes up the major portion of the atmosphere (78.08 percent by volume, 75.5 percent by weight). It is a colorless, odorless, tasteless, nontoxic, almost totally inert gas, and is colorless as a liquid. Nitrogen is nonflammable, will not support combustion, and is not life supporting. It combines with some of the more active metals such as lithium and magnesium to form nitrides, and at high temperatures it will also combine with hydrogen, oxygen, and other elements. It is used as an inert protection against atmospheric contamination in many nonwelding applications. Nitrogen is only slightly soluble in water and most other liquids, and is a poor conductor of heat and electricity. As a liquid at cryogenic temperatures it is nonmagnetic. It is shipped as a nonliquefied gas at pressures of 2000 psig (13 790 kPa) or above, and also as a cryogenic fluid at pressures and temperatures below 200 psig (1380 kPa) and -261°F (-163°C).

化学的特性

Nitrogen occurs naturally as approximately 78% v/v of the atmosphere. It is a nonreactive, noncombustible, colorless, tasteless, and odorless gas. It is often used under refrigeration as a cryogenic liquid. The boiling point is -195.8 °C and -320 °F. Nitrogen is not combustible. Nitrogen can combine with oxygen at high temperatures to form oxides and may form ammonia in contact with hydrogen at elevated temperatures. Cyanides can form if nitrogen is heated with carbon in presence of alkalies or barium oxide. If nitrogen comes in contact with ozone, nitrogen can oxidize explosively.It is usually handled as a compressed gas, stored in metal cylinders.

物理的性質

In its natural gaseous state, nitrogen is a relatively inert diatomic molecule (N2) that iscolorless, odorless, and tasteless, yet it is responsible for hundreds of active compounds. Itmakes up about 78% of the air we breathe. We are constantly taking it into our lungs withno stimulation or sensation; therefore, we really do not detect its presence. When liquefied, itis still colorless and odorless and resembles water in density. The melting point of nitrogen is–209.86°C, its boiling point is –195.8°C, and its density as a gas is 0.0012506 g/cm³.

同位体

There are 19 isotopes of nitrogen, two of which are stable. The stable ones andtheir proportion to the natural abundance of nitrogen on Earth follow: N-14 = 99.634%and N-15 = 0.366%. The other 17 isotopes are radioactive and man-made in nuclearreactors and have half-lives ranging from a few nanoseconds to 9.965 minutes.

名前の由来

From the two Greek words nitron and genes, which together stand for “soda or saltpeter forming.”

天然物の起源

Nitrogen is the 30th most abundant element on Earth. There is an almost unlimited sourceof nitrogen available to us considering that our atmosphere constitutes 4/5, or over 78%, ofthe nitrogen by volume. Over 33 million tons of nitrogen is produced each year by liquefyingair and then using fractional distillation to produce nitrogen as well as other gases in the atmosphere. During this process the air is cooled and then slowly warmed to fractionaltemperature points at which each specific gas in the air will “boil” off. (Note: Oxygen, argon,carbon dioxide, and nitrogen all have specific boiling points and these gases can be used tocollect the specific gas during the fractionation process.) When the temperature –reaches–195.8°C, the nitrogen is boiled off and collected.
There is a balance of nitrogen with other gases in the atmosphere that is maintained bywhat is called the nitrogen cycle. This cycle includes several processes, including nitrogen fixationof bacteria in the soil by legumes (bean and pea plants). Lightning produces nitrogen, asdo industrial waste gases and the decomposition products of organic material (i.e., organicproteins and amino acids in plants and animals contain nitrogen). In time, these sourcesreplace the nitrogen in the atmosphere to complete the cycle.
Ammonia (NH₃) is the first binary molecule discovered in outer space of our galaxy, theMilky Way. It may also be the main compound that forms the rings of the planet Saturn.

特性

There are approximately 4,000 trillion tons of gas in the atmosphere, and nitrogen makesup about 78% of these gases. It is slightly soluble in water and alcohol. It is noncombustibleand is considered an asphyxiant gas (i.e., breathing pure nitrogen will deprive the body ofoxygen).
Although nitrogen is considered an inert element, it forms some compounds that are veryactive. Of the diatomic molecules, such as CO₂ , it is difficult to separate the two atoms innitrogen’s molecules because of their strong binding energy. This is the reason that, along withcarbon dioxide, nitrogen gas is stable. However, once separated, the individual atoms of nitrogen(N) become very reactive and do combine with hundreds of other elements.
Nitrogen can be liquefied easily, making it useful in many applications wherein sustainedcooling is needed. At high temperatures, nitrogen reacts with many metals to form nitrides.

使用

In manufacture of ammonia, nitric acid, nitrates, cyanides, etc.; in manufacture of explosives; in filling high-temp thermometers, incandescent bulbs; to form an inert atm for preservation of materials, for use in dry boxes or glove bags. Liquid nitrogen in food-freezing processes; in the laboratory as a coolant. Pharmaceutic aid (air displacement).

定義

Nitrogen, N2, is a colorless,odorless, inert gas that comprises 80%of the earth's atmosphere. It serves as a diluent and controls natural burning and respiration rates, which would be much faster in higher concentrations of oxygen. Nitrogen is soluble in water and alcohol, but is essentially insoluble in most other liquids. It is essential to practically all forms of life and its compounds serve as foods or fertilizers. Nitrogen is used in the manufacture of ammonia and nitric acid. Nitrogen is essentially an inert gas at ambient and moderate temperatures. Therefore, it is easily handled by most metals.At elevated temperatures, nitrogen can be aggressive to metals and alloys.

調製方法

Nitrogen is obtained commercially, in large quantities, by the fractional distillation of liquefied air.

一般的な説明

A colorless odorless gas. Noncombustible and nontoxic. Makes up the major portion of the atmosphere, but will not support life by itself. Used in food processing, in purging air conditioning and refrigeration systems, and in pressurizing aircraft tires. May cause asphyxiation by displacement of air. Under prolonged exposure to fire or heat containers may rupture violently and rocket.

空気と水の反応

Slightly soluble in water.

反応プロフィール

These substances undergo no chemical reactions under any known circumstances except those under extreme conditions (liquid Nitrogen reacts violently in mixture with magnesium powder when a fuse is lit. Due to formation of magnesium nitride). Otherwise, they are nonflammable, noncombustible and nontoxic. They can asphyxiate.

危険性

Nitrogen is nontoxic, but it is an asphyxiate gas that cannot, by itself, support oxidation(combustion) or support life. If you breathe pure nitrogen for any period of time, you will die—not because the nitrogen gas is a poison, but because your body will be deprived of oxygen.
Nitrogen oxides are formed under certain conditions when nitrogen combines with oxygen,thus contributing to pollution. One source is from the internal combustion engine thatproduces NO similar to lightning. Once released, it combines with more oxygen to form ,which is a very reactive polluting gas. Nitrogen dioxide NO₂ is the main cause of “brown”smog over some cities and is harmful to plants, animals, and humans. To make matter worse,if there is adequate sunlight at the time of the smog, the ultraviolet light of the sun will breakdown the N and O of the NO₂ to form free radicals of oxygen that are reactive, forming ozone(O₃), which is itself a strong oxidizing agent that adds to pollution.
Several of the oxygen, hydrogen, and halogen compounds of nitrogen are toxic wheninhaled. A common error made in using household cleaners is to mix or use together ammoniacleaning fluids (containing nitrogen) and Clorox-type cleaning fluids (containing chlorine).The combined fumes can be deadly in any confined area. NEVER mix Clorox with ammoniatypecleaning fluids.

健康ハザード

Vapors may cause dizziness or asphyxiation without warning. Vapors from liquefied gas are initially heavier than air and spread along ground.

火災危険

Non-flammable gases. Containers may explode when heated. Ruptured cylinders may rocket.

工業用途

Nitrogen is often called an inert gas, and is used for some inert atmospheres for metal treating and in lightbulbs to prevent arcing, but it is not chemically inert. It is a necessary element in animal and plant life, and is a constituent of many useful compounds. Nitrogen combines with many metals to form hard nitrides useful as wear-resistant metals. Small amounts of nitrogen in steels inhibit grain growth at high temperatures, and also increase the strength of some steels. It is also used to produce a hard surface on steels.
Because of the importance of nitrogen compounds in agriculture and chemical industry, much of the industrial interest in elementary nitrogen has been in processes for converting elemental nitrogen into nitrogen compounds. The principal methods for doing this are the direct synthesis of ammonia from nitrogen and hydrogen, the electric arc process, which involves the direct combination ofN₂ and O₂ to nitric oxide, and the cyanamide process.

材料の用途

Gaseous nitrogen is noncorrosive and inert, and may consequently be contained in systems constructed of any common metals and designed to safely withstand the pressures involved. At the temperature of liquid nitrogen, ordinary carbon steels and most alloy steels lose their ductility and are considered unsafe for liquid nitrogen service. Satisfactory materials for use with liquid nitrogen include austenitic stainless steel (for example, types 304 and 316) and other nickel-chromium alloys, copper, Monel, brass, and aluminum.

薬理学

Atropine does not reactivate the phosphorylated AChE but competes with acetylcholine for binding with the muscarinic acetylcholine receptor acting as an antagonist.

安全性プロファイル

Low toxicity. In high concentrations it is a simple as-p~h yxiant. The release of nitrogen from solution in the blood, with formation of small bubbles, is the cause of most of the symptoms and changes found in compressed air illness (caisson disease). It is a narcotic at hgh concentration and hgh pressure. Both the narcotic effects and the bends are hazards of compressed air atmospheres such as found in underwater dving. Nonflammable gas. Can react violently with lithium, neodymium, titanium under the proper condtions. See also ARGON.

安全性

Nitrogen is generally regarded as a nontoxic and nonirritant material. However, it is an asphyxiant and inhalation of large quantities is therefore hazardous.

職業ばく露

Nitrogen is present in the air we breathe. Health effects may occur at concentrations above 80%. It has many medical and industrial uses including the quick freezing of food. The gas is used for purging, heat treating; food freezing; annealing, cooling, oil recovery; in the inert blanketing of sensitive materials and as a reactant in chemical synthesis of ammonia.

貯蔵

Nitrogen is stable and chemically unreactive. It should be stored in tightly sealed metal cylinders in a cool, dry place.

輸送方法

UN1066 Nitrogen, compressed, Hazard Class:, Hazard Class: 2.2; Labels: 2.2-Nonflammable compressed gas; UN1977 Nitrogen, refrigerated liquid cryogenic liquid, Hazard Class:, Hazard Class: 2.2; Labels: 2.2- Nonflammable compressed gas. Cylinders must be transported in a secure upright position, in a well-ventilated truck. Protect cylinder and labels from physical damage. The owner of the compressed gas cylinder is the only entity allowed by federal law (49CFR) to transport and refill them. It is a violation of transportation regulations to refill compressed gas cylinders without the express written permission of the owner.

不和合性

Containers may explode when heated. Liquid nitrogen is very unreactive, nonflammable, noncombustible and nontoxic. Contact with water may result in vigorous or violent boiling and extremely rapid vaporization. If the water is hot, there is the possibility that a liquid “superheat” explosion may occur. Pressures may build to dangerous levels if the liquid contacts water in a closed container.

廃棄物の処理

Return refillable compressed gas cylinders to supplier. Vent to atmosphere.

規制状況(Regulatory Status)

GRAS listed. Included in the FDA Inactive Ingredients Database (injections; dental preparations; nasal sprays; oral solutions; rectal gels). Accepted for use as a food additive in Europe. Included in parenteral and nonparenteral medicines licensed in the UK and USA. Included in the Canadian List of Acceptable Non-medicinal Ingredients.