炭素

外観

黒色の顆粒

炭素の同位体

天然に存在する同位体組成は、炭素12が98.90％、炭素13が1.10％、ほかに放射性同位体の炭素10、炭素11、炭素14、炭素15の4種類がある。炭素12は原子量の基準として選ばれ、炭素12原子1個の質量の12分の1が1原子質量単位である。炭素13のみが核スピンをもつので、核磁気共鳴吸収法による有機化合物の構造決定に利用される。

定義

本品は、木材又は竹などを加熱することによって得られる乾燥した炭化物である。

存在

宇宙には4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。ダイヤモンドは隕石(いんせき)中にもみつかっている。主として石灰石や方解石CaCO3、マグネサイトMgCO3、ドロマイトCaCO3・MgCO3のような炭酸塩として水成岩中に存在する。また、二酸化炭素として大気中に約0.03％含まれ、海水中の全炭酸（分子状のCO2のほかH2CO3、HCO3-、CO32-）はこれと平衡を保っている。燃料源として、また工業的に重要な化学薬品の原料となる石炭や石油の成分として、さらに有機化合物として生物圏の重要な構成成分である。生命の維持と機械その他の動力源として必要なエネルギーの大部分は、炭素とその化合物の酸化反応に仰いでいる。植物は空気中の二酸化炭素と水から光合成により炭水化物（含水炭素または糖類ともいう）を合成する。動物はこの炭水化物を摂取して呼吸作用により、また死後はバクテリアによる肉体組織の分解により二酸化炭素を大気に戻す。このような動物と植物を結び付ける鎖の輪が地表における炭素のサイクルである。

溶解性

水に不溶。

解説

ダイヤモンドは宝石として用いられるほか、その硬さを利用して研磨材や切削材料として用いられる。黒鉛は原子炉の中性子減速剤、各種の電極、るつぼ、鉛筆の芯、減摩材などに用いられる。無定形炭素はその形状や性質によって燃料その他いろいろな用途がある。粉末の活性炭は吸着材として重要であり、微粒子のカーボンブラックは顔料、印刷インキ、ゴムの充填(じゅうてん)剤などに用いられる。炭素繊維は高強度、高張性炭素繊維として各種スポーツ用品に用いられる。［守永健一・中原勝儼］

用途

カラムに充填し、有機溶剤蒸気の回収、触媒・触媒担体、浄水、排ガス中のSO2の除去。

用途

クロマトグラフ用カラム充填剤、上水処理、排水処理、浄水器。

用途

脱色、脱臭、吸着用。

用途

醸造品、医薬品、食品、化学薬品、染料中間物等の脱色・・脱臭精

用途

溶剤回収、ガス吸着、脱臭

用途

ガスクロマトグラフィー又は液体クロマトグラフィーカラム充填剤。

用途

クロマトグラフ用カラム充填剤、砂糖の脱色。中性で使用する場合に広範囲の用途に使用できる。

化粧品の成分用途

不透明化剤、吸着剤、研磨.スクラブ剤、着色剤

説明

All our SWNTs come packed as dry powders, which can be dispersed within the user's solvent of choice.

使用上の注意

微量のタール分が残留しているため、液体クロマトグラフにおいて溶離液によっては褐色に着色することがあります。この場合は、あらかじめ当該溶離液で洗浄した後に使用して下さい。

化学的特性

Carbon, C, is a nonmetallic element, grey solid. It is found in nature as graphite (specific gravity2.25), diamond(specific gravity 3.51), and coal (specific gravity 1.88). Carbon is found in all living things, is insoluble in common solvents,and forms an almost infinite numberof organic compounds. Anaturally occurring radioactive isotope,14C, has a half-life of 5780 years and is used in archaeo logical investigations to date artifacts and ancient documents. Other uses of carbon depend on its form. For example, diamonds for jewels and abrasives,graphite for lubricants, activated carbon to absorb color and gases, and wood carbon for fuel are some common examples.

同位体

There are 15 isotopes of carbon, two of which are stable. Stable carbon-12makes up 98.89% of the element’s natural abundance in the Earth’s crust, and carbon-13 makes up just 1.11% of carbon’s abundance in the Earth’s crust. All the otherisotopes of carbon are radioactive with half-lives varying from 30 nanoseconds (C-21) to5,730 years (C-14).

名前の由来

Carbon’s name is derived from the Latin word carbo, which means, “charcoal.”

天然物の起源

Carbon is the 14th most abundant element, making up about 0.048% of the Earth’s crust.It is the sixth most abundant element in the universe, which contains 3.5 atoms of carbonfor every atom of silicon. Carbon is a product of the cosmic nuclear process called fusion,through which helium nuclei are “burned” and fused together to form carbon atoms withthe atomic number 12. Only five elements are more abundant in the universe than carbon:hydrogen, helium, oxygen, neon, and nitrogen.

特性

Carbon is, without a doubt, one of the most important elements on Earth. It is the majorelement found in over one million organic compounds and is the minor component in mineralssuch as carbonates of magnesium and calcium (e.g., limestone, marble, and dolomite),coral, and shells of oysters and clams.The carbon cycle, one of the most essential of all biological processes, involves the chemicalconversion of carbon dioxide to carbohydrates in green plants by photosynthesis.
Animalsconsume the carbohydrates and, through the metabolic process, reconvert the carbohydratesback into carbon dioxide, which is returned to the atmosphere to continue the cycle.

使用

Crucibles, retorts, foundry facings, molds, lubricants, paints and coatings, boiler compounds, powder glazing, electrotyping, monochromator in X-ray diffraction analysis, fluorinated graphite polymers with fluorine-to-carbon ratios of 0.1–1.25, electrodes, bricks, chemical equipment, motor and generator brushes, seal rings, rocket nozzles, moderator in nuclear reactors, cathodes in electrolytic cells, pencils, fibers, self-lubricating bearings, intercalation compounds.

定義

The crystalline allotropic form of carbon.

一般的な説明

Black grains that have been treated to improve absorptive ability. May heat spontaneously if not properly cooled after manufacture.

空気と水の反応

Highly flammable. Dust is explosive when exposed to heat or flame. Freshly prepared material can heat and spontaneously ignite in air. The presence of water assists ignition, as do contaminants such as oils. Insoluble in water.

反応プロフィール

Carbon is incompatible with very strong oxidizing agents such as fluorine, ammonium perchlorate, bromine pentafluoride, bromine trifluoride, chlorine trifluoride, dichlorine oxide, chlorine trifluoride, potassium peroxide, etc. . Also incompatible with air, metals, unsaturated oils. [Lewis].

危険性

(Powder, natural) Fire risk.

健康ハザード

Fire may produce irritating and/or toxic gases. Contact may cause burns to skin and eyes. Contact with molten substance may cause severe burns to skin and eyes. Runoff from fire control may cause pollution.

火災危険

Flammable/combustible material. May be ignited by friction, heat, sparks or flames. Some may burn rapidly with flare burning effect. Powders, dusts, shavings, borings, turnings or cuttings may explode or burn with explosive violence. Substance may be transported in a molten form at a temperature that may be above its flash point. May re-ignite after fire is extinguished.

安全性プロファイル

Moderately toxic by intravenous route. Experimental reproductive effects. It can cause a dust irritation, particularly to the eyes and mucous membranes. See also CARBON BLACK, SOOT. Combustible when exposed to heat. Dust is explosive when exposed to heat or flame or oxides, peroxides, oxosalts, halogens, interhalogens, 02, (NH4NO3 + heat), (NH4ClO4 @ 240°), bromates, Ca(OCl)2, chlorates, (Cla + Cr(OCl)2), Cl0, iodates, 105, Pb(NO3)~, HgNO3, HNO3, (oils + air), (K + air), NaaS, Zn(NO3)a. Incompatible with air, metals, oxidants, unsaturated oils.

職業ばく露

Natural graphite is used in foundry facings, steel making lubricants, refractories, crucibles, pencil “lead,” paints, pigments, and stove polish. Artificial graphite may be substituted for these uses with the excep tion of clay crucibles; other types of crucibles may be pro duced from artificial graphite. Additionally, it may be used as a high temperature lubricant or for electrodes. It is uti lized in the electrical industry in electrodes, brushes, con tacts, and electronic tube rectifier elements; as a constituent in lubricating oils and greases; to treat friction elements, such as brake linings; to prevent molds from sticking together; and in moderators in nuclear reactors. In addition, concerns have been expressed about synthetic graphite in fibrous form. Those exposed are involved in production of graphite fibers from pitch or acrylonitrile fibers and the manufacture and use of composites of plastics, metals, or ceramics reinforced with graphite fibers.

輸送方法

UN1362 Carbon, activated, Hazard Class: 4.2; Labels: 4.2-Spontaneously combustible material, International.

純化方法

Charcoal (50g) is added to 1L of 6M HCl and boiled for 45minutes. The supernatant is discarded, and the charcoal is boiled with two more lots of HCl, then with distilled water until the supernatant no longer gives a test for chloride ion. The charcoal (now phosphate-free) is filtered onto a sintered-glass funnel and air dried at 120o for 24hours. [Lippin et al. J Am Chem Soc 76 2871 1954.] The purification can be carried out using a Soxhlet extractor (without cartridge), allowing longer extraction times. Treatment with conc H2SO4 instead of HCl has been used to remove reducing substances.

不和合性

Graphite is a strong reducing agent and reacts violently with oxidizers, such as fluorine, chlorine trifluoride, and potassium peroxide. Forms an explosive mixture with air. May be spontaneously combustible in air.

廃棄物の処理

Do not incinerate. Carbon (graphite) fibers are difficult to dispose of by incineration. Waste fibers should be packaged and disposed of in a land fill authorized for the disposal of special wastes of this nature, or as otherwise may be required by law.