Question

All Lewis acids are not bronsted acids. Why?

Answer 1

Answer:

According to Lewis concept, a base is a substance which can donate a pair of electron. ... HCl, H2SO4 are Bronsted acids because they can donate protons, but they cannot accept a pair of electrons to form a coordinate bond, therefore, they are not Lewis acids. Thus all Bronsted acids are not Lewis acids.

Answer 2

$\mathsf{BF_{3}}$ is a Lewis acid since it can accept an electron pair from other substances. Since $\mathsf{BF_{3}}$ does not contain Proton it can not act as bronsted acids.

Hence all Lewis acids need not to be bronsted acids