Final answer:
Silicon tetrachloride (SiCl4) can be synthesized by heating silicon dioxide with chlorine and carbon, or by the direct reaction of silicon with chlorine. It forms a covalent tetrahedral molecule and is sensitive to water, reacting to form orthosilicic acid which decomposes into SiO2.
Step-by-step explanation:
All the tetrahalides of silicon, SiX4, have been prepared, including silicon tetrachloride (SiCl4). This compound can be prepared through several methods, one of which is by the reaction of silicon dioxide with chlorine and carbon at elevated temperatures according to the equation: SiO2 (s) + 2C(s) + 2Cl2(g) → SiCl4 (g) + 2CO(g). Silicon tetrachloride is a covalent tetrahedral molecule, which is a nonpolar, colorless liquid with a low boiling point of 57 °C.
Another method to prepare silicon tetrachloride involves heating silicon with chlorine gas. Silicon reacts with halogens at high temperatures to form volatile tetrahalides. It is worth noting that silicon doesn't form double or triple bonds like carbon. Silicon compounds such as SiX4 can act as Lewis acids due to the high electronegativity of the halogens, resulting in the formation of six-coordinate silicon species in some cases.
When exposed to water, except for silicon tetrafluoride, silicon halides, including SiCl4, react vigorously, rapidly replacing the chlorine atoms with hydroxide groups to form unstable orthosilicic acid (Si(OH)4 or H4SiO4), which then slowly decomposes into SiO2.