red to orange powder
Lead tetroxide has many applications. The most important use is in paint and storage-batteries. It is used as a pigment in corrosion-protecting paints for steel surfaces. It also is used in positive battery plates; in colored glasses and ceramics; in glass sealants for television picture tubes; in propellants and explosives; in radiation shields for x-rays and gamma rays; in the vulcanization of rubber; in glass-writing pencils; in adhesives for tire cords; in foaming agents and waterproofing materials; in plasters and ointments; in lead dioxide matches; and as a catalyst for oxidation of carbon monoxide in exhausts.
Plasters and ointments; manufacture of colorless glass; glaze for faience; flux for porcelain painting, protective paint for iron and steel; oil-color for ship paints, varnishes; coloring rubber; cement for glass, gas and steam pipes; storage batteries; pencils for writing on glass; manufacture of lead peroxide, matches.
When heated above 550°C, the tetroxide decomposes to monoxide, evolving oxygen:
6Pb3O4→6PbO + O2
Lead tetroxide reacts with dilute nitric acid forming lead nitrate and precipitating lead dioxide:
Pb3O4 + 4HNO3 → 2Pb(NO3)2 + PbO2 + 2H2O
The above reaction may be explained by assuming lead tetroxide as formally equivalent to plumbus plumbate having a structure Pb2II[PbIVO4] in which Pb2+ dissolves in dilute nitric acid forming lead(II) nitrate while Pb4+ precipitates out as lead(IV) oxide.
Lead tetroxide reacts with anhydrous acetic acid at 80°C producing lead(II) acetate and lead(IV) acetate. Alternatively, the tetroxide is added into a mixture of glacial acetic acid and acetic anhydride and heated gently:
Pb3O4 + 8CH3COOH → 2Pb(CH3COO)2 + Pb(CH3Coo)4 + 4H2O
On cooling, the tetraacetate crystallizes, leaving diacetate in the solution. Acetic anhydride is added to react with water produced in the reaction to form acetic acid and thus prevent hydrolysis.
Lead tetroxide can be reduced to metallic lead when heated with reducing agents, such as hydrogen, carbon, or carbon monoxide:
Pb3O4 + 4H2→3Pb + 4H2O
Bright-red crystalline substance or amorphous powder; density 9.1 g/cm3; decomposes on heating to 500°C, melts at 830°C under pressure and oxygen; insoluble in water and alcohol; soluble in glacial acetic acid, hot hydrochloric acid, and a dilute nitric acid-hydrogen peroxide mixture.
Lead tetroxide is made by heating lead monoxide in the presence of air at temperatures between 450 to 500°C. The temperature should be maintained below 500°C, above which the tetroxide decomposes.
6PbO + O2→2Pb3O4
Alternatively, the tetroxide may be prepared by heating a mixture of lead monoxide and lead dioxide at 250°C:
2PbO + PbO2→Pb3O4