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Encyclopedia > Silica
Properties
General
Name Silicon dioxide
Chemical formula SiO2
Appearance Transparent solid
Physical
Formula weight 60.1 amu
Melting point 1986 K (1713 C)
Boiling point 2503 K (2230 C)
Density 2.6 103 kg/m3
Crystal structure Quartz, cristobalite or tridymite
Solubility 0.012 g in 100g water
Thermochemistry
ΔfH0gas -305.43 kJ/mol
ΔfH0liquid -899.86 kJ/mol
ΔfH0solid -910.86 kJ/mol
S0gas, 1 bar 228.98 J/molK
S0liquid, 1 bar  ? J/molK
S0solid 41.46 J/molK
Safety
Ingestion Low hazard.
Inhalation Irritation, long term exposure causes silicosis.
Skin May cause irritation.
Eyes May cause irritation.
More info Hazardous Chemical Database (http://ull.chemistry.uakron.edu/erd/chemicals/10/9916.html)
SI units were used where possible. Unless otherwise stated, standard conditions were used.

Disclaimer and references


The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2.


It is found in nature in several forms, including quartz and opal. In fact, silica has 17 crystalline forms. Also, horsetail is one of the plants which is rich in Silica.


It is manufactured in several forms including glass (in colorless high purity form called fused silica) and silica gel (used e.g. as desiccants in brand new clothes and leather goods). Silica is a major ingredient of Portland cement. The ceramic re-entry heat protection tiles mounted on the bottom side of the Space Shuttles are made mostly of silica.


Inhaling silica dust can lead to silicosis.


Further reading

  • R. K. Iler, The Chemistry of Silica (ISBN 047102404X)

  Results from FactBites:
 
Silicon dioxide - Wikipedia, the free encyclopedia (249 words)
Silica is a major ingredient of Portland cement.
The most common constituent of sand in inland continental settings and non-tropical coastal settings is silica, usually in the form of quartz because the considerable hardness of this mineral resists erosion.
Silica is also used as a food additive, primarily as a flow agent in powdered foods, or to absorb water.
  More results at FactBites »

 
 

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