Why $\ce{CCl4}$ does not dissolve in water while $\ce{SiCl4}$ does? Does it have to do with d-orbitals? If yes, then how are they related?
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2 Answers
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$\ce{SiCl_4}$ does not quite dissolve in water; rather, it reacts with water. So does $\ce{CCl_4}$, albeit extremely slowly, so for most purposes one may safely assume it doesn't. The difference is mostly due to the atomic size of C and Si. Smaller С atom is completely blocked off by four bulky chlorine atoms, so the water molecule can't reach it. Larger Si is easier to attack.
Another factor is that silicon is a less electronegative element than carbon, so that the Si-Cl bonds will have more polar character.
Whether or not the d-orbitals of silicon contribute significantly to the transition state, is (IMHO) a question of secondary importance.
answered Sep 9, 2015 at 8:46
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4$\begingroup$ Similarly, while methane will burn in air, silane is pyrophoric, that is it will spontaneously burst in to flame (and then there is disilane!). $\endgroup$ Sep 9, 2015 at 13:33
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A silicon tetrachloride reacts with water, while carbon tetrachloride does not. This is due to the fact that the carbon does not have d-orbitals to accept lone pair of electron from water, while silicon has vacant d-orbitals to accept lone pair of electron from water.
