Which intermolecular forces are present between two molecules of HI?

• A. Hydrogen bonding only
• B. London dispersion forces only
• C. London dispersion forces and dipole-dipole interactions
• D. Dipole-dipole interactions and hydrogen bonding

Answer: (C)

Verified step by step guidance

1. Identify the types of intermolecular forces: London dispersion forces, dipole-dipole interactions, and hydrogen bonding are the main types to consider for molecules like HI.
2. Determine if HI is polar: Since hydrogen iodide (HI) consists of hydrogen and iodine atoms with different electronegativities, the molecule is polar, meaning it has a permanent dipole moment.
3. Check for hydrogen bonding: Hydrogen bonding occurs only when hydrogen is directly bonded to highly electronegative atoms like nitrogen (N), oxygen (O), or fluorine (F). Since iodine is not one of these, HI cannot form hydrogen bonds.
4. Recognize that all molecules exhibit London dispersion forces due to temporary dipoles caused by electron movement, so HI molecules will have London dispersion forces.
5. Since HI is polar and cannot hydrogen bond, the intermolecular forces present between two HI molecules are London dispersion forces and dipole-dipole interactions.