Question

Do you expect the carbon hydrides of the type (C_nH_{2n + 2}) to act as ‘Lewis’ acid or base? Justify your answer.

Answer 1

For carbon hydrides of type C_nH_{2n + 2}, the following hydrides are possible for

`"n" = 1 => "CH"_4`

`"n" = 2 => "C"_2"H"_6`

`"n" = 3 => "C"_3"H"_8`

For a hydride to act as a Lewis acid i.e., electron-accepting, it should be electron-deficient. Also, for it to act as a Lewis base i.e., electron donating, it should be electron-rich.

Taking C₂H₆ as an example, the total number of electrons is 14 and the total covalent bonds are seven. Hence, the bonds are regular 2e^–-2 centered bonds.

Hence, hydride C₂H₆ 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.