Question

Do you expect the carbon hydrides of the type $\left(C_n{H}_{2n+2}\right)$ to act as 'Lewis' acid or base? Justify your answer.

Answer 1

For carbon hydrides of type $C_n{H}_{2n+2}$, the following hydrides are possible for
$n=1\Rightarrow C{H}_4$
$n=2\Rightarrow C_2{H}_6$
$n=3\Rightarrow C_3{H}_8$
$⋮⋮$
For a hydride to act as a Lewis acid i.e., electron accepting, it should be electrondeficient. Also, for it to act as a Lewis base i.e., electron donating, it should be electronrich.
Taking $C_2{H}_6$ as an example, the total number of electrons are 14 and the total covalent bonds are seven. Hence, the bonds are regular $2e^{-}-2$ centered bonds.

Hence, hydride $C_2{H}_6$ has sufficient electrons to be represented by a conventional Lewis structure. Therefore, it is an electron-precise hydride, having all atoms with complete octets. Thus, it can neither donate nor accept electrons to act as a Lewis acid or Lewis base.