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| General | |
|---|---|
| Name | Silicon dioxide |
| Chemical formula | Si O2 |
| 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, cristobaliteCommon in volcanic rocks, cristobalite is a polymorph of quartz. or tridymite |
| Solubility | 0.012 gFor other meanings of gram see gram (disambiguation). The gram (also spelt gramme is a unit of measurement of mass, and is defined in the SI system of units as one thousandth of a kilogram. See 1 E -3 kg for comparisons with other masses. The symbol for g in 100g water |
| Thermochemistry | |
| ΔfH0gasThe standard enthalpy of formation of a compound is the change of enthalpy that accompanies the formation of 1 mole of that substance from its component elements, at their standard states (the most stable form of the element or compound at 25 degrees Cels | -305.43 kJThe joule (symbol J also called newton metre or coulomb volt is the SI unit of energy and work. The unit is pronounced to rhyme with "tool", and is named in honour of the physicist James Prescott Joule (1818-1889). 1 joule 1 N · 1 m 1 newton · 1 metre 1 k/ molThe mole (symbol: mol) is one of the seven SI base units and is commonly used in chemistry. It measures the amount of substance of a system and is defined as the amount of substance that contains as many elementary entities as there are atoms in exactly 0 |
| 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 |
| Safety | |
| Ingestion | Low hazard. |
| Inhalation | Irritation, long term exposure causes silicosis. |
| Skin | May cause irritation. |
| Eyes | May cause irritation. |
| More info | Hazardous Chemical Database |
| 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 Si O2.
It is found in nature in several forms, including quartz and opal. 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.