Lead (IV) oxide (PbO2) is also known as lead dioxide. It is a brown substance important in
the operation of the lead-acid storage battery.
Description
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).
Chemical Properties
brown to black powder
Chemical Properties
Lead dioxide is a dark brown crystalline solid
or powder.
Physical properties
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.
Occurrence
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.
Uses
Lead dioxide is a strong oxidizing agent that is used in the manufacture of matches, pyrotechnics, dyes and other chemicals. It also has several important applications in the electrochemical industry, in particular as a component of lead–acid batteries used in almost all types of vehicles.
Uses
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Industry
Application
Role/benefit
Electrochemistry
Regenerating potassium dichromate
Anode material/inexpensive and has high oxygen evolution over voltage
Electroplating copper and zinc in sulfate baths
Oxidation electrolytic by clarification Water
Production of glyoxylic acid from oxalic acid in a sulfuric acid electrolyte
Lead acid batteries
Rubber
Vulcanized rubber
Vulcanizing agent
Chemical analysis
Organic elemental analysis and chromatographic analysis
Analytical reagent
Others
Production of matches, pyrotechnics, dyes
Additive
High-voltage lightning arresters
Resistor element
Coating of pipes
Helps to reduce lead contamination of drinking water
Uses
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.
Preparation
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.
General Description
Brown, hexagonal crystals. Insoluble in water. Used in matches, explosives, electrodes.
Reactivity Profile
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].
Health Hazard
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.
Fire Hazard
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.
Potential Exposure
This material is used in electrodes for
lead-acid batteries; in matches; explosives, and as a curing
agent for polysulfide elastomers
Shipping
UN1872 Lead dioxide, Hazard Class: 5.1;
Labels: 5.1-Oxidizer.
Incompatibilities
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
Waste Disposal
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.
Lead dioxide Preparation Products And Raw materials
