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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Sophia7X on February 15, 2013, 11:48:34 PM

Title: Lewis definition
Post by: Sophia7X on February 15, 2013, 11:48:34 PM
Which is an acid base reaction according to the Lewis definition but NOT Bronsted-Lowry?

A.) MgCl2(s)  ::equil:: 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?
Title: Re: Lewis definition
Post by: Dan on February 16, 2013, 06:22:33 AM
Quote from: Sophia7X on February 15, 2013, 11:48:34 PM
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.

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

The two are not mutually exclusive.