Question

1)Both HF and HCl are molecules having a polar covalent bond. Their boiling points are 293 K and 188 K respectively. (i) State which property of the atoms involved causes a bond to be polar.

2)Explain, in terms of the intermolecular forces present in each compound, whyHF has a higher boiling point than HCl

Answer 1

HF has a higher boiling point than HCl due to its ability to form hydrogen bonds, which are a strong type of dipole-dipole attraction. Hydrogen bonding arises from the significant electronegativity difference between fluorine and hydrogen.

Step-by-step explanation:

The property of atoms that causes a bond to be polar is a difference in electronegativity between the atoms involved. Molecules with a permanent dipole moment, such as HF and HCl, experience dipole-dipole attractions, which are stronger than dispersion forces. HF has a higher boiling point than HCl because of its ability to form hydrogen bonds, which are a special type of dipole-dipole attraction. Hydrogen fluoride (HF) can form hydrogen bonds due to the high electronegativity of fluorine and the presence of a hydrogen atom. This intermolecular force is significantly stronger than the dipole-dipole interactions present in HCl, which does not form hydrogen bonds. The greater strength of hydrogen bonding in HF results in a higher boiling point compared to HCl.