Question

HBr is a stronger acid than HCl. Which of the following explanations best presents the causality of this acidity order?

a. The entropy loss of water is the smallest when the conjugate base ion is larger.

b. The conjugate base ion is more stable when it is larger.

c. The energetic stability of the conjugate base ion is greater when the ion is larger.

d. Water likes to bond with the conjugate base of HBr more than HCl.

Answer 1

Both b and c options are same and are correct.

HCl and HBr when dissociate gives rise to the corresponding halide ions, Cl^- and Br^-​.These ions are called the conjugate bases of corresponding acids. Larger the size of an ion higher its stability since the charge is spread over a larger area.

Option d is also correct. Because larger the size of an ion higher the solvation around it which makes the corresponding conjugate acid readily available. Since Br^- ion is larger than Cl^- ion it is hydrated better. ​