Why is hydrogen fluoride a weak acid compared with the other hydrogen halides?

Hydrogen fluoride (HF) is a weak acid compared to other hydrogen halides (HCl, HBr, and HI) primarily due to the strength of the bond between the hydrogen and fluorine atoms.12

While acidity in a group of hydrides generally increases as the group is descended—a trend driven by decreasing bond strength—the H–F bond is exceptionally strong. This high bond energy makes it significantly more difficult for the hydrogen ion ($H^{+}$) to dissociate from the fluorine atom in an aqueous solution compared to the other hydrogen halides, where the bond strength is lower.12

Additionally, while factors such as electronegativity and ionic solvation energy play roles in determining acid strength, the bond strength remains the most critical factor in explaining why HF does not dissociate completely in water like its heavier counterparts.2