Other Definitions
silicon dioxide (dict)

Silicon Dioxide

font size="+1">Properties
olspan="2" align=center bgcolor="#FFDEAD"| General
Name Silicon dioxide
Chemical formula SiO2
Appearance Transparent solid
olspan="2" align="center" bgcolor="#FFDEAD"| 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
olspan="2" align="center" bgcolor="#FFDEAD"| Thermochemistry
ΔfH0gas -305.43 kJ/mol
ΔfH0liquid -899.86 kJ/mol
ΔfH0solid -910.86 kJ/mol
S0gas, 1 bar 228.98 J/mol·K
S0liquid, 1 bar ? J/mol·K
S0solid 41.46 J/mol·K
olspan="2" align="center" bgcolor="#FFDEAD"| Safety
Ingestion Low hazard.
Inhalation Irritation, long term exposure of the crystalline form causes silicosis.
Skin May cause irritation.
Eyes May cause irritation.
More info Hazardous Chemical Database
olspan="2" align="center" bgcolor="#FFDEAD"| 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, many forms of life include silica structures, including microorganisms such as diatoms, plants such as horsetail, and animals such as hexactinellid sponges. It is manufactured in several forms including glass (in colorless high purity form called fused silica), synthetic amorphous 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, as are the firebricks used in steel processing. Inhaling crystalline silica dust can lead to silicosis.

Further reading

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

 

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