In a pure sample of HF, which types of intermolecular forces exist between the molecules?

• A. Only dipole-dipole forces
• B. Hydrogen bonding, dipole-dipole forces, and London dispersion forces
• C. Only London dispersion forces
• D. Ionic bonding and London dispersion forces

Answer: (B)

Verified step by step guidance

1. Identify the type of molecule HF is: HF is a polar molecule because fluorine is highly electronegative, creating a significant dipole moment with hydrogen.
2. Recognize that HF molecules can form hydrogen bonds because hydrogen is directly bonded to fluorine, a highly electronegative atom with lone pairs, which is a key requirement for hydrogen bonding.
3. Understand that dipole-dipole forces exist between polar molecules like HF due to the attraction between the positive end of one molecule and the negative end of another.
4. Remember that all molecules, including HF, exhibit London dispersion forces (also called van der Waals forces) because these are present in all molecular interactions due to temporary fluctuations in electron density.
5. Conclude that the intermolecular forces present in pure HF are hydrogen bonding, dipole-dipole forces, and London dispersion forces, while ionic bonding does not occur because HF is a covalent molecular compound.