Question

Account for the following : (i) `PbX_(2)` is more stable than `PbX_(4) (X = Cl, Br)`
(ii) `PbCl_(4)` is more stable than `SnCl_(4)` but `PbCl_(2)` is more stable than `SnCl_(2)`,
(iii) `PbCl_(4)` is less stable than `SnCl_(4)` ?

Answer 1

(i) Due to inert pair effect, the +2 oxidation state of Pb is more stable than `+4`. Hence, `PbX_(2)` is more stable than `PbX_(4)`. (ii) Stability of `+4` oxidation state decreases down the group while that of `+2` oxidation state increases due to inert pair effect. (iii) Same as (ii).