Hydrogen Sulfide - Leucaiso

H ₂ S (34.08). Its systematic name is sulfane. It is usually called hydrogen sulfide or dihydrogen sulfide. At room temperature, it is a colorless gas with a distinctive rotten egg odor. It is naturally found in volcanic gases, mineral and hot spring waters, crude oil, natural gas, etc. It is also produced by the decay of animal and plant proteins. In laboratories, it was often made by reacting iron sulfide (II) with dilute hydrochloric acid, but this method contains various impurities, so commercially available H ₂ S cylinders are often used. Industrially, it can also be made by reacting sulfur vapor with hydrogen under high-temperature catalyst, but nowadays it is mainly recovered from natural gas, petroleum refining, and industrial exhaust gases. The gas has a broken HSH curve, with ∠HS-H92° (90° for the liquid), and H-S1.35 Å. Its melting point is -85.5 °C, and its boiling point is -60.7 °C. Its density is 0.993 g cm ^-3 (-60 °C). 1 g of _H2S dissolves in 242 ^cm3 of water at 20°C (about twice as much as _CO2 ). Its aqueous solution is a weak acid _with pK1 _7.02 and pK2 13.9. When heated, it begins to decompose at about 400°C, and at 1700°C it completely splits into _H2 and S. When ignited in air, it burns with a blue flame and produces _SO2 and _H2O . Its aqueous solution is unstable, and becomes cloudy as sulfur precipitates when oxidized by air. It reacts with metals, metal oxides, metal salts, etc. to form sulfides. It also reacts with elemental halogens (such as _Cl2 ). It has a wide range of uses, including as a main raw material for the production of sulfur and sulfuric acid, in the manufacturing process of chemicals (pharmaceuticals, industrial chemicals, phosphors, heavy water, etc.), for the separation and purification of metals, for the removal of metals from HCl, _{H2SO4 , etc.} , and as an analytical reagent. It is highly flammable and combustible. It has a strong toxicity comparable to HCN, causing damage to the central nervous system, cardiovascular system, and respiratory system. It has a strong odor that can be detected even at 0.1 ppm in the air, but olfactory paralysis occurs at 120 ppm, and death occurs with one breath at 800-1000 ppm. Dangerous and harmful substances requiring notification of names, etc. under the Industrial Safety and Health Act. Specified substance under the Air Pollution Control Act. [CAS 7783-06-4]

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

H₂S(34.08)．体系名はスルファン．通常は硫化水素ないし硫化二水素とよぶ．室温では特異な腐卵臭をもつ無色の気体．天然に，火山ガス，鉱泉・温泉水，原油・天然ガスなどに含まれる．また，動物，植物のタンパク質の腐敗により発生する．実験室では，硫化鉄(Ⅱ)と希塩酸との反応でつくることが多かったが，この製法では各種不純物が含まれるので，市販のH₂Sのボンベを使うことが多い．工業的には，硫黄蒸気と水素との高温触媒下での反応でもつくりうるが，いまは天然ガス，石油精製，工業排気ガスなどからの回収が主である．気体はH-S-Hの折れ線形で，∠H-S-H92°(液体では90°)，H-S1.35 Å．融点－85.5 ℃，沸点－60.7 ℃．密度0.993 g cm^－3(－60 ℃)．1 g のH₂Sは20 ℃ で242 cm³ の水に溶ける(CO₂の約2倍)．水溶液は弱酸で，pK₁ 7.02，pK₂ 13.9．加熱すると，約400 ℃ で分解しはじめ，1700 ℃ で完全に H₂ とSに分かれる．空気中で点火すると青い炎をあげて燃え，SO₂とH₂Oを生じる．水溶液は不安定で，空気酸化を受けて硫黄を析出して白濁する．金属，金属酸化物，金属塩などと反応して硫化物をつくる．単体ハロゲン(Cl₂ など)とも反応する．硫黄・硫酸の主要製造原料，化学薬品などの製造工程で使用(医薬品，工業薬品，蛍光体，重水など)，金属の分離精製，HCl，H₂SO₄などからの金属除去，分析用試薬など広い用途がある．きわめて可燃性・引火性が高い．中枢神経系，心臓血管系，呼吸器系に障害もたらす，HCNに匹敵する強い毒性をもつ．空気中に0.1 ppm 存在しても検知できる強い悪臭をもつが，120 ppm で嗅覚麻ひが起こり，800～1000 ppm では一呼吸で死亡する．労働安全衛生法・名称等を通知すべき危険物及び有害物．大気汚染防止法特定物質．[CAS 7783-06-4]

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