Question

Why is HF the weakest acid among hydrohalo acids inspite of the fact that fluorine is most electronegative?

Answer 1

1. HF is the weakest acid among hydrohalo acids despite fluorine being the most electronegative because the \[\ce{H - F}\] bond is very strong and has the highest bond dissociation energy (574 kJ/mol).
2. This strong \[\ce{H - F}\] bond requires more energy to break, making dissociation into H₃O⁺ and F⁻ ions difficult.
3. Acid strength depends on the ease of bond dissociation, so HF is less likely to release H⁺ ions compared to other hydrohalic acids.
4. Hence, HF has weaker acidity even though fluorine’s electronegativity suggests it should be stronger.