Which of the following Lewis acid-base reactions are not Bronsted acid-base reactions ?

Question

a) CH3COOH(aq) + NH3(aq) = CH3COO-(aq) + NH4 +(aq)

b) Cu 2+(aq) + 4NH3(aq) = Cu(NH3)42+(aq)

c) Al(OH)3(s) + OH-(aq) --> Al(OH)4-(aq)

d) AgCl(s) + 2NH3(aq) --> (NH3)2Ag+(aq) + Cl -(aq)

Answer 1

Bronsted-Lowry theory requires an acid to give up a H+, and a base to accept it. Lewis theory yammers on about electron pairs.

In a), acetic acid is a Lewis acid, and ammonia is a Lewis base. H+ is transferred from acetic acid to ammonia, so it meets BL criteria as well.

In b), NH3 is a Lewis base, and Cu 2+ a Lewis acid.
But Cu2+ is not a BL acid (no H+ donated)

In c), OH - is a Lewis base, and Al(OH)3 a Lewis acid.
But they are not BL acid and base (no H+ transferred)

In d), NH3 is a Lewis base, so AgCl is a Lewis acid.
But AgCl did not give up H+, so it is not a BL acid.