Silicon dioxide
Oxide of silicon / From Wikipedia, the free encyclopedia
Dear Wikiwand AI, let's keep it short by simply answering these key questions:
Can you list the top facts and stats about Silica?
Summarize this article for a 10 year old
SHOW ALL QUESTIONS
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.
"Silica" redirects here. For other uses, see Silica (disambiguation).
Quick Facts Names, Identifiers ...
A sample of silicon dioxide | |
Names | |
---|---|
IUPAC name
Silicon dioxide | |
Other names
| |
Identifiers | |
ChEBI | |
ChemSpider |
|
ECHA InfoCard | 100.028.678 |
EC Number |
|
E number | E551 (acidity regulators, ...) |
200274 | |
KEGG |
|
MeSH | Silicon+dioxide |
PubChem CID |
|
RTECS number |
|
UNII | |
CompTox Dashboard (EPA) |
|
| |
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 to |
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) |
1.544 (o), 1.553 (e)[1]: 4.143 |
Hazards | |
NFPA 704 (fire diamond) | |
NIOSH (US health exposure limits): | |
PEL (Permissible) |
TWA 20 mppcf (80 mg/m3/%SiO2) (amorphous)[2] |
REL (Recommended) |
TWA 6 mg/m3 (amorphous)[2] Ca TWA 0.05 mg/m3[3] |
IDLH (Immediate danger) |
3000 mg/m3 (amorphous)[2] Ca [25 mg/m3 (cristobalite, tridymite); 50 mg/m3 (quartz)][3] |
Related compounds | |
Related diones |
Carbon dioxide |
Related compounds |
Silicon monoxide |
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).
|
Close
Silicon dioxide is a common fundamental constituent of glass.