Question
Justify the statement: All Bronsted bases are Lewis bases, but all Bronsted acids are not Lewis acids.
Solution
(i) All Bronsted bases are also Lewis bases: According to Bronsted concept, the base is a substance which accepts a proton. According to Lewis concept, a base is a substance which can donate a pair of electron. Any substance which can donate a pair of an electron can easily accept a proton.
Thus all Bronsted bases are all Lewis bases.
(ii) All Bronsted acids are not Lewis acids: According to Bronsted concept, an acid is a substance that can donate a proton (H+). According to Lewis concept, an acid is any substance (molecule or ion) which can accept a pair of electrons from another substance to form a coordinate bond. 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.
Thus all Bronsted bases are all Lewis bases.
(ii) All Bronsted acids are not Lewis acids: According to Bronsted concept, an acid is a substance that can donate a proton (H+). According to Lewis concept, an acid is any substance (molecule or ion) which can accept a pair of electrons from another substance to form a coordinate bond. 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.
