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解説
塩素，元素記号 Cl ，原子番号 17，原子量 35.4527。天然に存在する安定同位体には塩素 35 (存在比 75.4%) ，37 (24.6%) の2種が存在する。 1774年 K.シェーレにより発見，1810年 H.デービーにより元素と認められた。周期表 17族に属するハロゲンの1つ。電子親和力が大きく，1価の陰イオンになりやすい。海水1l中には約 19gの塩化物イオン (食塩として約 30g) が含まれている。工業的にはアルカリ金属塩化物の水溶液あるいは溶融塩電解によって多量に生産される。実験室的には，二酸化マンガンに濃塩酸をそそいで簡単に得られる。単体は二原子分子 Cl2 で常温では黄緑色，刺激臭のある気体。有毒。空気中に 4ppm含まれると臭気を感じ，30ppmで激しく咳込む。－34.05℃または 5.7気圧，20℃で液化し，黄緑の液体となる。化学的には非常に活発で，希ガス，炭素以外の全元素と反応する。水素や金属粉末は塩素中で激しく燃焼し，特に水素との混合物に点火すると爆発するので，塩素爆鳴気といわれる。合成ゴム，プラスチック，殺虫剤，炭化水素の塩素化合物のほか非常に多数の化学薬品類の製造に使われる。また，酸化剤，漂白剤，飲料水の殺菌剤としても広く利用される。
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用途
塩化ビニル、塩素系溶剤などの有機塩素化合物及び無機塩素化合物の原料、紙?パルプ繊維の漂白、上下水道の消毒殺菌、香料医薬品、農薬の製造、鉱石製錬や金属の回収、粘土ケイ砂などの鉄分除去
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歴史
1774年スウェーデンのシェーレが、塩酸を二酸化マンガンで酸化するとき、黄緑色の気体が発生することをみいだした。1810年イギリスのH・デービーが新元素であることを結論し、ギリシア語で黄緑色を意味するchlorosにちなんで命名した。日本語の塩素は、これが代表的な塩としての塩化ナトリウムNaClの成分であることに基づいている。
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存在
遊離の状態では存在せず、おもに海水や岩塩中にアルカリ金属およびアルカリ土類金属の塩（NaCl、KCl、MgCl2など）として存在する。天然の同位体組成は35Cl（75.4％）、37Cl（24.6％）である。
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性質
常温で黄緑色、刺激臭のある有毒気体で、冷却すると黄色液体を経て黄白色の固体となる。水にかなりよく溶ける。水溶液は0℃に冷却するとクラスレイト化合物（包接化合物）である水和物Cl2・7.7H2Oが得られる。塩素ガスを飽和させた水は塩素水といい、黄緑色の溶液である。漂白作用があり、溶液中には塩酸と次亜塩素酸を生じている。この加水分解反応は冷たい水酸化アルカリ溶液中で100％進む。塩素は化学的に非常に活発で、不活性気体、酸素、窒素、炭素以外のすべての元素単体と直接化合して、塩化物をつくる。水素と混ぜてもそのままでは反応しないが、光、熱、電気火花などで反応が誘導されると、爆発的に反応が進む（連鎖反応）ので、水素と塩素との混合気体を塩素爆鳴気という。いろいろな種類の化合物があり、－Ⅰから＋Ⅶまでの酸化数をとるが、おもに奇数の場合が多い。塩素が、より陽性の強い元素と化合した塩化物中では、塩素の酸化数は－Ⅰである。酸化物には、一酸化二塩素Cl2O、二酸化塩素ClO2、六酸化二塩素Cl2O6、七酸化二塩素Cl2O7があるが、いずれも不安定で爆発性がある。オキソ酸には、次亜塩素酸HClO（＋Ⅰ）、亜塩素酸HClO2（＋Ⅲ）、塩素酸HClO3（＋Ⅴ）、過塩素酸HClO4（＋Ⅶ）があり、それぞれの塩もある（括弧(かっこ)内は酸化数）。塩化ヨウ素IClのようなハロゲン間化合物なども知られている。
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説明
Chlorine is a greenish-yellow, nonflammable
gas with a distinctive, pungent odor. It is almost
two and one-half times as heavy as air. The gas
acts as a severe irritant if inhaled. Chlorine liquid
has the color of clear amber and is about
one and one-half times as heavy as water. It is
shipped as a compressed liquefied gas having a
vapor pressure of 86.767 psig at 70°F (598.26
kPa at 21.1°C). Chlorine is nonflammable in
both gaseous and liquid states. However, like
oxygen, it is capable of supporting the combustion
of certain substances. Many organic chemicals
react readily with chlorine, in some cases
with explosive violence. Chlorine usually forms
univalent compounds, but it can combine with a
valence of 3, 4,5, or 7.
Chlorine is only slightly soluble in water.
When it reacts with pure water, weak solutions
of hydrochloric and hypochlorous acids are
formed. Chlorine hydrate (Cl2·8H20) may crystallize
below 49.3°F (9.61°C).
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用途
水道水や汚水の殺菌および漂白などに多量に用いられるほか、塩酸、さらし粉など多数の無機塩化物や、有機塩素化合物（農薬、医薬、爆発薬、フロン、塩化ビニルなど）の製造原料として広い用途がある。
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化学的特性
Chlorine is a greenish-yellow gas. Pungent,
irritating odor. Shipped as a liquefied compressed gas. It is
the commonest of the four halogens which are among the
most chemically reactive of all the elements. It is not flammable; but it is a strong oxidizer, and contact with other
materials may cause fire.
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物理的性質
As a nonmetal, chlorine exists as a greenish-yellow gas that is corrosive and toxic at roomtemperatures. As a halogen, chlorine is not found in the elemental (atomic) state but formsdiatomic gas molecules (Cl2). As a very active negative ion with the oxidation state of -1,chlorine forms bonds with most metals found in groups I and II.
Chlorine is noncombustible but will support combustion. It is extremely electronegativeand a strong oxidizing agent. It is not as strong as fluorine, which is just above it in group 17,but is stronger than the other halogens.
As a gas, its specific gravity (density) is 3.214g/l or 0.003214g/cm3. As a liquid, it is aclear amber color with a density of 1.56g/cm3. Its melting point is –101.5°C, and its boilingpoint is –34.04°C.
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同位体
There are a total of 25 isotopes of chlorine. Of these, only two are stable andcontribute to the natural abundance on Earth as follows: Cl-35 = 75.77% and Cl-37 =24.23%. All the other 23 isotopes are produced artificially, are radioactive, and have halflivesranging from 20 nanoseconds to 3.01×10+5 years.
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名前の由来
From the Greek word khl?ros, meaning “greenish yellow.”
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天然物の起源
Chlorine is the 20th most abundant element on the Earth. It is not found as a free element(atoms) except as a diatomic gas escaping from very hot active volcanoes. It has been knownfor thousands of years as rock salt (halite). It is also found in sylvite and carnallite and as achloride in seawater. In nature, it is mostly found in dissolved salts in seawater and deposits insalt mines. Its best-known compound is sodium chloride (NaCl), which is common table salt.Chlorine is important for the chemical industry. Numerically, it is the 12th most producedchemical in the United States and ranks ninth in volume of chemicals produced in the UnitedStates.
Chlorine is produced commercially by the electrolysis of a liquid solution of sodium chloride(or seawater), through which process an electric current is passed though the solution(electrolyte).
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特性
Chlorine’s best-known characteristic is its smell. It can be detected when used as householdbleach or as an antiseptic in swimming pools. As an antiseptic, it is added to municipal drinkingwater supplies. Chlorine gas has a very pungent odor that is suffocating when inhaled. Ina more concentrated form, Cl2 was also a deadly poisonous gas used in combat during WorldWar I. Because it combines with so many other elements, particularly metals, chlorine is fundamentalto many industries, particularly the plastics industry.
Laboratory amounts of chlorine (Cl2) are produced by combining hydrochloric acid (HCl)with manganese dioxide (MnO2). The HCl provides the Cl-1 ion.
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使用
The largest quantities of chlorine are used in manufacturing chemicals. These include:
• Solvents such as trichloroethylene, I, I, I-trichloroethane, perchloroethylene, and methylene chloride
• Pesticides, herbicides, and other agricultural products
• Plastics, rubbers, and fibers such as polyvinyl chloride and neoprene
• Refrigerants and propellants such as the halocarbons and methyl chloride
Chlorine is also an ingredient in bleach or sodium hypochlorite solutions. In addition, chlorine is used in bleaching pulp, paper, and textiles; for drinking and swimming water purification; in the sanitation of industrial and sewage wastes; and for the purification ofaluminum.
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定義
chlorine: Symbol Cl. A halogen element;a.n. 17; r.a.m. 35.453; d. 3.214g dm–3; m.p. –100.98°C; b.p. –34.6°C.It is a poisonous greenish-yellowgas and occurs widely in nature assodium chloride in seawater and ashalite (NaCl), carnallite (KCl.MgCl2.6H2O), and sylvite (KCl). It is manufacturedby the electrolysis of brineand also obtained in the Downsprocess for making sodium. It hasmany applications, including thechlorination of drinking water,bleaching, and the manufacture of alarge number of organic chemicals.
It reacts directly with many elementsand compounds and is astrong oxidizing agent. Chlorinecompounds contain the element inthe 1, 3, 5, and 7 oxidation states. Itwas discovered by Karl Scheele in1774 and Humphry Davy confirmedit as an element in 1810.
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調製方法
Chlorine is principally produced by electrolysis of NaCl
or KCl brine in either diaphragm, mercury, or membrane
cathode cells. In these processes, gaseous chlorine is released
at the anode and caustic is a by-product. Chlorine may also be
produced by electrolysis of hydrochloric acid (HCl) [7647-
01-0], by oxidation of HCl in the presence of nitrogen oxide
as a catalyst (Kel-Chlor process), or as a coproduct from
metal production.
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製法
工業的には、おもに食塩水の電解（隔膜法）によって、また融解塩化物の電解によって製造される。実験室では、塩酸を二酸化マンガンや過マンガン酸カリウムなどの強力な酸化剤で酸化するか、重金属塩化物を熱分解するか、あるいはさらし粉Ca(OCl)Clに塩酸を作用させるなどの方法が行われる。塩素は黄色のボンベに詰めて市販される。
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毒性
塩素は第一次世界大戦で毒ガスとして用いられた。
塩素の人体に対する無害の限度は1ppmであるという。空気中に0.003～0.006％存在するだけで粘膜が冒され、鼻炎をおこし、涙、咳(せき)などが出る。長時間吸入すると胸が痛み、血を吐いて呼吸困難となる。塩素濃度の高いところでは、呼吸困難とともにチアノーゼをおこして死に至るので、直接吸わないように注意が必要である。
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人体に含まれる塩素
塩素の多くは食塩NaClとして摂取される。人体の塩素の90％は、塩素イオンとして、血液、そのほかの体液の成分として存在し、浸透圧の調節や水素イオン濃度指数（pH）の維持にかかわっている。また、一部は、胃酸の構成部分である塩酸として、胃液とともに胃の中に分泌される。胃酸は、タンパク質消化酵素であるペプシンの活性化に必要であり、また、食物中の不用な菌類の殺菌の働きがある。この殺菌によって、腸内での有用細菌の発育を容易にする効果がある。
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空気と水の反応
Water dissolves about twice its volume of Chlorine gas, forming a mixture of hydrochloric acid and hypochlorous acids. Will be corrosive due to acidity and oxidizing potential.
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危険性
A series of chlorofluorohydrocarbons that are used as refrigerants are being phased out ofmanufacture and use, because of their possible deleterious effects on the ozone layer of theatmosphere. (See the entry on oxygen for more on the ozone layer.)
From time to time, railroad tank cars are involved in accidents that will leak liquid orgaseous chlorine that, when escaping into the air, forms toxic chlorine compounds. This isextremely dangerous, both as a fire hazard and for human health. When water is used to flushaway the escaping chlorine, it may end up as hydrochloric acid, which can be hazardous tothe water supply and to aquatic life.
Concentrated chlorine gas and many chlorine compounds will oxidize powdered metals,hydrogen, and numerous organic materials and release enough heat to generate fires or explosions.Chlorine is constantly evaporating from the oceans and drifting into the atmospherewhere it causes a natural depletion of the ozone.
Warning: One should never mix, or use together, chlorine cleaners, such as Clorox, withother cleaning substances containing ammonia. It is a deadly mixture.
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健康ハザード
Chlorine is a respiratory irritant. It causes irritation to the mucous membranes and the
liquid burns the skin. The poisoning caused by chlorine depends on the amount of chlorine a person or an occupational worker is exposed to, and the length of exposure time.
Prolonged exposures to high concentrations of chlorine cause poisoning with symptoms
that include, but are not limited to, coughing, burning sensation in the nose, throat, and
eyes, blurred vision, nausea, vomiting, pain, redness, and blisters on the skin, chest tightness, and pulmonary edema.
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火災危険
May ignite other combustible materials (wood, paper, oil, etc.). Mixture with fuels may cause explosion. Container may explode in heat of fire. Vapor explosion and poison hazard indoors, outdoors or in sewers. Hydrogen and Chlorine mixtures (5-95%) are exploded by almost any form of energy (heat, sunlight, sparks, etc.). May combine with water or steam to produce toxic and corrosive fumes of hydrochloric acid. Emits highly toxic fumes when heated. Avoid plastics and rubber. Avoid heat and contact with hydrogen gas or powdered metals.
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燃焼性と爆発性
Chlorine is noncombustible but is a strong oxidizer and will support combustion of
most flammable substances.
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化学性质
強い酸化性を有し，多くの金属および非金属材料を腐食するが，乾燥塩素は腐食性がほとんどなく，炭素鋼でも十分に使用できる。
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使用用途
塩素は水にかなり溶けやすく、水溶液には漂白作用と殺菌作用があります。この性質を利用して、水道水やプールの消毒、漂白剤などに使われています。ただし、塩素系の漂白剤を酸性の洗剤などと混ぜると有毒な塩素ガスを生じるため、取り扱いには注意が必要です。
塩素化合物は、プラスチック製品、工業部品、医薬品など、幅広い分野で利用されています。化学工業製品の基礎的な原料として、塩素は欠かせない物質です。
主に塩化ナトリウムの形で人体に摂取され、血液や体液の成分として存在します。特に、は胃酸の構成要素として、消化を促進する役割を担っています。
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既存の形態
地球上には天然元素の中で、塩素は18番目に多く存在する元素です。気体、鉱物、イオンのような状態でマントル中に99.6%、地殻中に0.3%、海水中に0.1%含まれています。
地球の質量のおよそ6×1027gに対して、マントルには22×1024g、地殻におよそ60×1021gの塩素が存在すると考えられています。海水の平均塩素濃度は19.354g/kgです。そのため、およそ1.36×108km3の海水のうち、主に塩化ナトリウムの状態で、26×1021gの塩素が存在すると予想されています。
それ以外にも、河川水、湖水、地下水だけでなく、雪氷圏、対流圏、成層圏などにも、あらゆる形で塩素が含まれています。
塩素には、32〜40g/molの同位体が存在します。安定同位体は75.77%含む35Clと24.23%含む37Clの2つです。
環境中には放射性同位体である36Clが、わずかに存在しています。安定同位体に対する36Clの存在比は、およそ7×10-13です。宇宙線中の陽子と36Arの衝突で破砕して36Clが生成しているほか、地表では35Clの中性子捕獲や40Caのミュー粒子捕獲でも36Clが生成します。
36Clの半減期は30万8,000年であり、36Sや36Arに崩壊します。36Clは親水性で、不活性な同位体です。よって36Clは、6万年〜100万年の放射年代測定に役立ちます。その上、1952年〜1958年に実施された大気中核実験で、大量の36Clが海水から生じました。大気中の36Clの残留時間は1週間であり、過去50年間の地下水の年代を知ることも可能です。
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材料の用途
At ordinary temperatures, dly chlorine, either
liquid or gas, does not corrode steel. In the presence
of moisture, however, highly corrosive conditions
exist due to the formation of hydrochloric
and hypochlorous acids. Thus precautions should
be taken to keep chlorine and equipment free of moisture. Piping, valves, and containers should
be closed or capped when not in use to keep atmospheric
moisture out ofthe system.
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職業ばく露
Environmental danger. Chlorine is a
toxic gas with corrosive properties. Gaseous chlorine is
widely used as a bleaching agent in the paper, pulp, and
textile industries for bleaching cellulose for artificial fibers.
It is used in the manufacture of chlorinated lime; inorganic
and organic compounds, such as metallic chlorides; chlorinated solvents; refrigerants, pesticides; and polymers, e.g.,
synthetic rubber and plastics; it is used as a disinfectant,
particularly for water and refuse; and in detinning and
dezincing iron. CL has been used as a warfare choking/pulmonary agent. Note: The lowest level at which humans can
detect chlorine through smell and become alert to its irritant properties generally provides sufficient warning of
exposure. However, chronic exposure to chlorine causes
olfactory fatigue and tolerance to its irritant effects. Those
with a history of prolonged exposure to chlorine, may eventually lose their ability to identify incidents of exposure.
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概要
塩素とは、元素記号がClで表されるハロゲン元素です。
一般的に塩素と呼ぶ場合には、塩素の単体である塩素分子 (Cl2) を指すことが多いです。塩素原子は、NaClやMgCl2のような金属の塩として主に存在しています。自然界だけでも1,500種類以上の塩素化合物があります。
工業的には、食塩水や融解塩化物の電気分解によって製造可能です。電気分解によって発生した塩素ガスは、高圧によって液体となり、ボンベやタンクに充填されます。
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発がん性
In the chronic inhalation bioassay
with rats and mice exposed to 0, 0.4, 1.0, or 2.5 ppm chlorine
for 2 years, described above, incidence of neoplasia in the
nasal passages was not increased by exposure, even though
there were exposure-dependent lesions in the nasal tissues
(199). Chlorine has not been identified as a carcinogen
(IARC 1999).
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貯蔵
All work with chlorine should be conducted in a fume hood to prevent exposure
by inhalation, and splash goggles and impermeable gloves should be worn at all times to
prevent eye and skin contact. Cylinders of chlorine should be stored in locations appropriate
for compressed gas storage and separated from incompatible compounds such as hydrogen,
acetylene, ammonia, and flammable materials.
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輸送方法
UN1017 Chlorine, Hazard Class: 2.3; Labels:
2.3-Poisonous gas, 5.1-Oxidizer, 8-Corrosive material,
Inhalation Hazard Zone B. 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. Military driver shall be given full
and complete information regarding shipment and conditions in case of emergency. AR 50-6 deals specifically with
the shipment of chemical agents. Shipments of agent will
be escorted in accordance with AR 740-32.
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合成方法
食塩電解法による
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純化方法
Pass the gas in succession through aqueous KMnO4, dilute H2SO4, conc H2SO4, and a drying tower containing Mg(ClO4)2. Or bubble it through water, dry it over P2O5 and distil it from bulb to bulb in a vacuum line. One volume of water dissolves 4.6 volumes of Cl2 at 0o, 2.15 volumes at 20o, 1.22 volumes at 50o and 0.39 volumes at 90o. [Schmeisser in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 272 1963.] HIGHLY TOXIC.
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不和合性
A powerful oxidizer. Reacts explosively
or forms explosive compounds with many organic compounds and common substances, such as acetylene, ether,
turpentine, ammonia, fuel gas, hydrogen, and finely divided
metals. Keep away from combustible substances and reducing agents. Corrosive to some plastic, rubber, and coating
materials. Reacts with water to form hypochlorous acid.
Corrosive to many metals in presence of water.
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廃棄物の処理
Return refillable compressed
gas cylinders to supplier. Introduce into large volume and
solution of reducing agent (bisulfite, ferrous salts, or hypo),
neutralize and flush to sewer with water. Recovery is an
option to disposal for chlorine in the case of gases from
aluminum chloride electrolysis and chlorine in waste
waters. See also “Spill Handling.” Nonrefillable cylindersshould be disposed of in accordance with local, state, and
federal regulations. Allow remaining gas to vent slowly
into atmosphere in an unconfined area or exhaust hood.
Refillable-type cylinders should be returned to original supplier with any valve caps and outlet plugs secured and
valve protection caps in place.
