Silicon dioxide
A sample of silicon dioxide | |
| Names | |
|---|---|
| IUPAC name
Silicon dioxide | |
Other names
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| Identifiers | |
| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.028.678 |
| EC Number |
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| E number | E551 (acidity regulators, ...) |
| 200274 | |
| KEGG | |
| MeSH | Silicon+dioxide |
PubChem CID |
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| RTECS number |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| SiO2 | |
| Molar mass | 60.08 g/mol |
| Appearance | Transparent or white |
| Density | 2.648 (α-quartz), 2.196 (amorphous) g·cm−3 |
| Melting point | 1,713 °C (3,115 °F; 1,986 K) (amorphous): 4.88 |
| Boiling point | 2,950 °C (5,340 °F; 3,220 K) |
| −29.6·10−6 cm3/mol | |
| Thermal conductivity | 12 (|| c-axis), 6.8 (⊥ c-axis), 1.4 (am.) W/(m⋅K): 12.213 |
Refractive index (nD) |
1.544 (o), 1.553 (e): 4.143 |
| Hazards | |
| NFPA 704 (fire diamond) | |
| NIOSH (US health exposure limits): | |
PEL (Permissible) |
TWA 20 mppcf (80 mg/m3/%SiO2) (amorphous) |
REL (Recommended) |
TWA 6 mg/m3 (amorphous) Ca TWA 0.05 mg/m3 |
IDLH (Immediate danger) |
3000 mg/m3 (amorphous) Ca [25 mg/m3 (cristobalite, tridymite); 50 mg/m3 (quartz)] |
| Related compounds | |
Related diones |
Carbon dioxide Germanium dioxide Tin dioxide Lead dioxide |
Related compounds |
Silicon monoxide Silicon disulfide |
| Thermochemistry | |
Std molar entropy (S⦵298) |
42 J·mol−1·K−1 |
Std enthalpy of formation (ΔfH⦵298) |
−911 kJ·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references | |
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO2, commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant families of materials, existing as a compound of several minerals and as a synthetic product. Examples include fused quartz, fumed silica, opal, and aerogels. It is used in structural materials, microelectronics, and as components in the food and pharmaceutical industries. All forms are white or colorless, although impure samples can be colored.
Silicon dioxide is a common fundamental constituent of glass.