Question

Mention some of the important characteristics with suitable explanation of hydrogen halides.

Answer 1

1. Physical state: HF is a low-boiling liquid due to hydrogen bonding; others (HCl, HBr, and HI) are gases because they lack hydrogen bonding.
2. Thermal stability: HF is most stable; stability decreases from HF to HI owing to decreasing \[\ce{H - X}\] bond strength.
3. Reducing character: Increases from HF (no reducing power) to HI (strong reducing agent) due to weaker \[\ce{H - X}\] bond.
4. Acidic nature: In aqueous solution, all ionise to give H₃O⁺ ions; acid strength increases from HF (weakest) to HI (strongest).
5. Bond strength and size: Larger halogen atoms form weaker \[\ce{H - X}\] bonds, decreasing stability and increasing acid strength.