Every Bronsted-Lowry acid is also a Lewis acid.
Why is this statement false?
Thanks
Scroll down about half the page to Bronsted Acidity of some Lewis acids and some examples are given (Mg for example).
http://en.wikipedia.org/wiki/Br%C3%B8nsted%E2%80%93Lowry_acid-base_theory
This statement is false because while every Lewis acid can act as a Bronsted-Lowry acid, not every Bronsted-Lowry acid can act as a Lewis acid.
To understand why this is the case, we need to understand the definitions of these two acid classification systems.
According to the Bronsted-Lowry acid-base theory, an acid is a substance that donates a proton (H+ ion) to another substance. In this theory, the concept of electron pairs is not explicitly considered.
On the other hand, the Lewis acid-base theory defines an acid as a substance that can accept an electron pair. According to this theory, acids are electron pair acceptors.
Now, considering these definitions, it becomes clear that while every Lewis acid can also act as a Bronsted-Lowry acid by accepting a proton, not every Bronsted-Lowry acid can act as a Lewis acid. This is because not every Bronsted-Lowry acid has the ability to accept an electron pair.
For example, consider hydrochloric acid (HCl). It can act as a Bronsted-Lowry acid by donating a proton (H+), but it cannot act as a Lewis acid because it does not have the ability to accept an electron pair.
In conclusion, while every Lewis acid can act as a Bronsted-Lowry acid, not every Bronsted-Lowry acid can act as a Lewis acid, making the statement "Every Bronsted-Lowry acid is also a Lewis acid" false.