Silicon tetrachlorideSilicon tetrachloride
) is a colourless volatile liquid. It's most commonly prepared by reacting chlorine
with hot silicon
- Si + 2 Cl2 → SiCl4
Silicon tetrachloride has a density
of 1.483 g/cm3
, a melting point
of -70°C, and a boiling point
of 57.6°C. It reacts violently with water, in contrast with carbon tetrachloride
. This hydrolysis
reaction occurs because the atomic radius of the silicon atom is such that the water molecules can attack it, whereas carbon has a smaller atomic radius than silicon so the chlorine atoms effectively shield the carbon from attack. In water, the following reaction occurs:
- SiCl4 + 2 H2O → SiO2 + 4 HCl
Other oxidants, strong acids, alcohols, bases, ketones, and aldehydes can also react with it to produce hydrogen chloride. It has corrosive effects on the skin, eyes and lungs.
Silicon tetrachloride is sometimes used as an intermediate in the purification of silicon.