산화납(Ⅳ)

개요Lead 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).

출처Lead 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.

용도Lead 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.

일반 설명Brown, hexagonal crystals. Insoluble in water. Used in matches, explosives, electrodes.

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.