Chapter 18, Problem 63A

Explain how the definition of a Lewis acid differs from the definition of a Bronsted-Lowry acid.

Interpretation Introduction

Interpretation:

The difference between Lewis acid and Bronsted-Lowry acid is to be explained.

Concept introduction:

According to Lewis concept,

Acid is a substance which is electron acceptor.

According to Bronsted-Lowry,

Acid is a substance which donates hydrogen ion.

Answer to Problem 63A

Acid which is electron acceptor is Lewis acid and which is hydrogen ion donor is Bronsted acid.

Explanation of Solution

All Lewis acids are not Bronsted acids and all Bronsted acids are not Lewis acids.

$AlC{l}_3$is a Lewis acid as it is electron deficient and accepts electron from donor species. But it can’t give $H^{+}$. Therefore, it is not Bronsted-Lowry acid.

$HCl$ donates $H^{+}$but is not electron deficient. So it is Bronsted-Lowry acid but not Lewis acid.

Conclusion

Thus, All Lewis acids are not Bronsted acids and all Bronsted acids are not Lewis acids