Question
Explain why silicon tetrachloride is hydrolyzed but carbon tetrachloride is not hydrolysed.
Solution
CCl4 is not hydrolysed by water because carbon has no d-orbitals and hence cannot expand its coordination number beyond 4. However, silicon atom of silicon tetrachloride has energetically suitable vacant d-orbitals. Thus, it can accept a lone pair of electrons from oxygen atom of a water molecule. Therefore, silicon atom can expand its coordination number beyond four. Due to this reason SiCl4 is hydrolysed.
In this reaction, all the four chlorine atoms of SiCl4 are replaced by four OH groups.
In this reaction, all the four chlorine atoms of SiCl4 are replaced by four OH groups.
