A compound amongst BcL3,alcl3,fecl3,pcl3 which cannot act as lewis acid

pcl3

To determine which compound cannot act as a Lewis acid, we need to understand what a Lewis acid is.

A Lewis acid is a substance that can accept a pair of electrons, known as a Lewis base. In the case of these compounds, BcL3, AlCl3, FeCl3, and PCl3, they all have vacant orbitals that can accept a pair of electrons, which makes them potential Lewis acids.

However, one way to identify whether a compound acts as a Lewis acid is to look at its Lewis acidity trend. This trend is commonly observed for Group 15 elements (such as P) compared to Group 13 elements (such as B and Al).

The elements in Group 15, like phosphorus (P), have a larger atomic radius and higher electronegativity compared to the elements in Group 13, like boron (B) and aluminum (Al). Due to these factors, elements in Group 15 have a higher tendency to act as a Lewis base rather than a Lewis acid.

So, from the given compounds, PCl3 is the compound that cannot act as a Lewis acid. This is because phosphorus (P) is more likely to act as a Lewis base, donating its electrons, rather than accepting electrons.

In summary, among the compounds BCl3, AlCl3, FeCl3, and PCl3, PCl3 cannot act as a Lewis acid because phosphorus (P) is more inclined to act as a Lewis base.