Lead dioxide
 |
|
 |
|
| Names | |
|---|---|
|
IUPAC name
Lead(IV) oxide
|
|
| Other names
Plumbic oxide
Plattnerite |
|
| Identifiers | |
1309-60-0 
|
|
| ECHA InfoCard | 100.013.795 |
| PubChem | 14793 |
| RTECS number | OGO700000 |
| UN number | 1872 |
| Properties | |
| PbO2 | |
| Molar mass | 239.1988 g/mol |
| Appearance | dark-brown, black powder |
| Density | 9.38 g/cm3 |
| Melting point | 290 °C (554 °F; 563 K) decomposes |
| insoluble | |
| Solubility | soluble in acetic acid insoluble in alcohol |
|
Refractive index (nD)
|
2.3 |
| Structure | |
| hexagonal | |
| Hazards | |
| Safety data sheet | External MSDS |
|
EU classification (DSD)
|
Repr. Cat. 1/3 Xn (Xn) N (N) |
| R-phrases | R61, R20/22, R33, R62, R50/53 |
| S-phrases | S53, S45, S60, S61 |
| NFPA 704 | |
| Flash point | Non-flammable |
| Related compounds | |
|
Other cations
|
Carbon dioxide Silicon dioxide Germanium dioxide Tin dioxide |
|
Lead(II) oxide Lead(II,IV) oxide |
|
|
Related compounds
|
Thallium(III) oxide Bismuth(III) oxide |
|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|
|
 (what is  ?) |
|
| Infobox references | |
Lead(IV) oxide, commonly called lead dioxide or plumbic oxide or anhydrous plumbic acid is a chemical compound with the formula PbO2. It is an oxide where lead is in an oxidation state +4. It is of an intermediate bond type, displaying both ionic (e.g. the lattice structure) and covalent (e.g. its low melting point and insolubility in water) properties. It is an odorless dark-brown crystalline powder which is nearly insoluble in water. It exists in two crystalline forms. The alpha phase has orthorhombic symmetry; it has been first synthesized in 1941 and identified in nature as a rare mineral scrutinyite in 1988. The more common, tetragonal beta phase was first identified as the mineral plattnerite around 1845 and later produced synthetically. Lead dioxide is a strong oxidizing agent which is used in the manufacture of matches, pyrotechnics, dyes and other chemicals. It also has several important applications in electrochemistry, in particular in the positive plates of lead acid batteries.
Lead dioxide is an odorless dark-brown crystalline powder which is nearly insoluble in water. It has two major polymorphs, alpha and beta, which occur naturally as rare minerals scrutinyite and plattnerite, respectively. Whereas the beta form had been identified in 1845, α-PbO2 was first identified in 1946 and found as a naturally occurring mineral 1988.
The alpha form has orthorhombic symmetry, space group Pbcn (No. 60), Pearson symbol oP12, lattice constants a = 0.497 nm, b = 0.596 nm, c = 0.544 nm, Z = 4 (four formula units per unit cell). The lead atoms are 6 coordinate. The symmetry of the beta form is tetragonal, space group P42/mnm (No. 136), Pearson symbol tP6, lattice constants a = 0.491 nm, c = 0.3385 nm, Z = 2 and related to the rutile structure and can be envisaged as containing columns octahedra sharing opposite edges and joined to other chains by corners. This contrasts with the α- form where the octahedra are linked by adjacent edges to give zig-zag chains. Lead dioxide decomposes upon heating in air as follows:
...
Wikipedia