Why does hydrogen fluoride (HF) have a higher boiling point than hydrogen chloride (HCl)?
Answer and explanation
Correct answer: A. HF molecules form hydrogen bonds
- Step 1: Hydrogen bonds form when H is bonded to F, O or N.
- Step 2: More energy is needed to separate hydrogen-bonded molecules, so HF boils at a higher temperature.
Answer
HF molecules form hydrogen bonds.
Why not the others: The H–F covalent bond is stronger than the H–Cl bond: covalent bonds are not broken when boiling. HF has more electrons than HCl: HCl has more electrons. HF forms ions in the liquid: liquid HF is molecular.
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