A sample of silicon dioxide
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Names | |
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IUPAC name
Silicon dioxide
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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[1] |
Melting point | 1,713 °C (3,115 °F; 1,986 K) (amorphous)[1]: 4.88 |
Boiling point | 2,950 °C (5,340 °F; 3,220 K)[1] |
−29.6·10−6 cm3/mol | |
Thermal conductivity | 12 (|| c-axis), 6.8 (⊥ c-axis), 1.4 (am.) W/(m⋅K)[1]: 12.213 |
Refractive index (nD)
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1.544 (o), 1.553 (e)[1]: 4.143 |
Hazards | |
NFPA 704 (fire diamond) | |
NIOSH (US health exposure limits): | |
PEL (Permissible)
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TWA 20 mppcf (80 mg/m3/%SiO2) (amorphous)[2] |
REL (Recommended)
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TWA 6 mg/m3 (amorphous)[2] Ca TWA 0.05 mg/m3[3] |
IDLH (Immediate danger)
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3000 mg/m3 (amorphous)[2] Ca [25 mg/m3 (cristobalite, tridymite); 50 mg/m3 (quartz)][3] |
Related compounds | |
Related diones
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Carbon dioxide Germanium dioxide Tin dioxide Lead dioxide |
Related compounds
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Silicon monoxide Silicon disulfide |
Thermochemistry | |
Std molar
entropy (S⦵298) |
42 J·mol−1·K−1[4] |
Std enthalpy of
formation (ΔfH⦵298) |
−911 kJ·mol−1[4] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO2, commonly found in nature as quartz.[5][6] In many parts of the world, silica is the major constituent of sand. Silica is abundant as it comprises several minerals and synthetic products. All forms are white or colorless, although impure samples can be colored.
Silicon dioxide is a common fundamental constituent of glass.
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