[Sophia7X]

Which is an acid base reaction according to the Lewis definition but NOT Bronsted-Lowry?

A.) MgCl2(s)  Mg⁺² + 2Cl^-. This is not even an acid base reaction. Just a solid dissolving. However, the answer key marks this as the answer.

B.) CN- + H2O <--> HCN + OH-. Transfer of proton = Bronsted Lowry.

C.) NH3(g) + HBr(g) <--> NH4Br(s). Couldn't NH3 be a Lewis base (forms coordinate covalent bond with hydrogen; donates electron pair?) however, this is also an acid base reaction according to Bronsted-Lowry, and the question says which can only be by the Lewis definition.

D.) Fe(H2O)6⁺³ + H2O <--> [Fe(H2O)5OH]⁺² + H3O+, just an acid ionizing in water, transfer of proton involved.


Just a bad question, or am I missing something?

[Dan]

Just a bad question, or am I missing something?

What is the definition of a Lewis acid/base?

Magnesium chloride is an odd choice to demonstrate the idea, and I don't think it is a very good one, but I can see what they're getting at. Think about BMe₃ + NH₃3 instead.

This is not even an acid base reaction. Just a solid dissolving

The two are not mutually exclusive.