Question

Account for the following:

HI in aqueous solution is a stronger acid than hydrochloric acid.

Answer 1

1. HI is a stronger acid than HCl because its \[\ce{H - I}\] bond dissociates more easily in water, releasing more H₃O⁺ ions.
2. The bond dissociation energy of \[\ce{H - I}\] (295 kJ/mol) is lower than that of \[\ce{H - Cl}\] (432 kJ/mol), so \[\ce{H - I}\] breaks more readily.
3. Although chlorine is more electronegative, bond strength governs acid strength in these halides.
4. Hence, HI has greater acid strength due to the weaker \[\ce{H - I}\] bond and easier proton release in aqueous solution.