Trichlorosilane

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**Properties**
General

Name	Trichlorosilane
Chemical formula	H Si Cl₃
Appearance	Colourless liquid
Physical
Formula weight	135.5 amu
Melting point	146 K (-127 °C)
Boiling point	305 K (32 °C)
Density	1.34 ×10³ kg/m³ (liquid)
Solubility	decomposes in water
Thermochemistry
Δ_fH⁰_gas	-496.22 kJ/mol
Δ_fH⁰_liquid	? kJ/mol
Δ_fH⁰_solid	? kJ/mol
S⁰_{gas, 1 bar}	313.72 J/mol·K
S⁰_{liquid, 1 bar}	? J/mol·K
S⁰_solid	? J/mol·K
Safety
Ingestion	May cause nausea, vomiting, kidney damage.
Inhalation	May cause burning in chest, dizziness, pulmonary edema, cardiac irregularity, kidney damage.
Skin	Possible burns, especially on wet skin.
Eyes	Produces burning and tearing with possible cornea damage.
More info	Hazardous Chemical Database
SI units were used where possible. Unless otherwise stated, standard conditions were used. Disclaimer and references

Trichlorosilane is a chemical compound containing silicon, hydrogen, and chlorine. At high temperatures, it decomposes to produce silicon, and as such, purified trichlorosilane is the principal source of ultrapure silicon in the semiconductor industry. In water, it rapidly decomposes to produce a silicone polymer while giving off hydrochloric acid. Because of its reactivity and wide availability, it is frequently used in the synthesis of silicon-containing organic compounds.

[edit] Production

Industrially, trichlorosilane is produced by blowing hydrogen chloride through a bed of silicon powder at 300°C. There, they combine to make trichlorosilane and hydrogen according to the chemical equation

Si + 3 HCl → HSiCl₃ + H₂

A properly designed reactor can achieve a yield of 80-90% trichlorosilane. The major byproducts are silicon tetrachloride (chemical formula SiCl₄), hexachlorodisilane (Si₂Cl₆), and dichlorosilane (H₂SiCl₂), from which trichlorosilane can be separated by distillation.

The reverse process is used for the production of silicon metal of higher purity.