二酸化鉛

解説

PbO2(239.20)．酸化鉛(Ⅳ)ともいう．二酸化鉛は，鉛(Ⅱ)塩を臭素水などの酸化剤で酸化すると得られる．黒褐色の等軸晶系の粉末．結晶構造はルチル型構造．密度9.38 g cm－3．熱，冷水，エタノールに不溶，濃硫酸，硝酸に微溶．カセイアルカリの濃水溶液に溶けて鉛酸塩を生じる．光分解を受けて四酸化三鉛と酸素を，加熱すると三酸化二鉛と酸素を，塩化水素を作用させると塩化鉛(Ⅱ)，水，塩素を生じる．過酸化水素によって還元されて酸化鉛(Ⅱ)となり，硫黄やリンとはげしく反応してこれらを酸化する．酸化剤，鉛蓄電池(バッテリー)の正極板，マッチ，爆薬，媒染剤，染料製造，プラスチック硬化剤などに用いられる．有毒．森北出版「化学辞典（第2版）

説明

Lead dioxide, PbO₂, also plumbic oxide, is an odorless dark-brown crystalline powder which is nearly insoluble in water. It exists in two crystalline forms. The a phase has orthorhombic symmetry, lattice constants a=0.497 nm, b=0.596 nm, c= 0.544 nm, Z=4 (four formula units per unit cell).

化学的特性

Lead dioxide is a dark brown crystalline solid or powder.

物理的性質

Red tetragonal crystals or brown powder; density 9.64 g/cm³; decomposes on heating at 290°C; practically insoluble in water; also insoluble in alkalis; moderately soluble in hydrochloric acid and also, in nitric acid-hydrogen peroxide mixture; slowly dissolves in acetic acid.

天然物の起源

Lead dioxide occurs in nature as the mineral plattnerite. It is used as an oxidizing agent in manufacturing dyes and intermediates. It also is used as a source of oxygen in matches, pyrotechnics, and explosives. In matches, the oxide is combined with amorphous phosphorus as an ignition surface. It also is used in making lead pigments, liquid polysulfide polymers and rubber substitutes. Lead dioxide electrodes are used in lead storage batteries in which lead dioxide accumulates on positive plates.

使用

Lead dioxide occurs in nature as the mineral plattnerite. It is used as an oxidizing agent in manufacturing dyes and intermediates. It also is used as a source of oxygen in matches, pyrotechnics, and explosives. In matches, the oxide is combined with amorphous phosphorus as an ignition surface. It also is used in making lead pigments, liquid polysulfide polymers and rubber substitutes. Lead dioxide electrodes are used in lead storage batteries in which lead dioxide accumulates on positive plates.

製造方法

Lead dioxide is produced by oxidizing an alkaline slurry of lead monoxide with chlorine, sodium hypochlorite, or bleaching powder. Alternatively, it is obtained by passing chlorine into a hot aqueous suspension of lead sulfate and magnesium hydroxide. The ionic reaction is:
Pb(OH)_3ˉ +ClOˉ → PbO₂ + Clˉ+ OHˉ + H₂O
It also is produced by electrolysis of acidic solutions of lead salts using a lead or platinum electrode. In such electrolytic process, lead dioxide is deposited on the anode of the cell.
Insoluble powdered lead dioxide also may be obtained when lead tetroxide is heated with nitric acid:
Pb₃ O₄ + 4HNO₃ → 2Pb(N)₃)₂ + PbO₂ + 2H₂O
Lead dioxide also can be prepared by fusing lead monoxide with a mixture of sodium nitrate and sodium chlorate.

一般的な説明

Brown, hexagonal crystals. Insoluble in water. Used in matches, explosives, electrodes.

反応プロフィール

Noncombustible but accelerates the burning of combustible material. Reacts violently with hydrogen sulfide [Bretherick 1979. p. 977-978]. Ignites with hydroxylamine [Mellor 8:291. 1946-47]. Reacts violently with hydrogen peroxide [Mellor 1:937 1946-47], with phenylhydrazine [Mellor 7:637 1946-47], or with sulfuryl chloride [Mellor 10:676. 1946-47]. Reacts with incandescence with sulfur dioxide [Mellor, 1941, Vol. 7, 689]. Explodes when ground with boron or yellow phosphorus [Mellor, 1946, Vol. 5, 17]. Mixtures with sulfur and red phosphorus ignite [Mellor, 1941, Vol. 7, 689]. Reacts vigorously when heated with calcium sulfide, strontium sulfide or barium sulfide [Mellor, 1941, Vol. 3, 745].

健康ハザード

Toxic by ingestion. Inhalation of dust is toxic. Fire may produce irritating, corrosive and/or toxic gases. Contact with substance may cause severe burns to skin and eyes. Runoff from fire control or dilution water may cause pollution.

火災危険

These substances will accelerate burning when involved in a fire. May explode from heat or contamination. Some may burn rapidly. Some will react explosively with hydrocarbons (fuels). May ignite combustibles (wood, paper, oil, clothing, etc.). Containers may explode when heated. Runoff may create fire or explosion hazard.

職業ばく露

This material is used in electrodes for lead-acid batteries; in matches; explosives, and as a curing agent for polysulfide elastomers

輸送方法

UN1872 Lead dioxide, Hazard Class: 5.1; Labels: 5.1-Oxidizer.

不和合性

Lead dioxide is a powerful oxidizer. Violent reaction with many compounds, including reducing agents; chemically active metals; combustible materials, strong acids, alkaline earth sulfides, aluminum carbides, aluminum, amines, calcium sulfide, carbides, chlorine trifluoride, glycerin, hydrides, hydrochloric acid, hydrogen peroxide, hydrogen sulfide, hydroxylamine, magnesium, metal powders, metal sulfides, molybdenum, phenylhydrazine, phosphorous red/friction, phosphorous trichloride, silicon, sulfides, sulfur, sulfur dioxide, sulfur/friction, sulfuric acid, tungsten, hydrogen trisulfide

廃棄物の処理

Conversion to soluble salt, precipitation as sulfide and return to supplier. Do not discharge into drains or sewers. Dispose of waste material as hazardous waste using a licensed disposal contractor to an approved landfill. Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Containers must be disposed of properly by following package label directions or by contacting your local or federal environmental control agency, or by contacting your regional EPA office.