Questions: Considering only intermolecular forces, predict which substance would have the highest boiling point (hint: it may not be the substance with the actual highest boiling poin HI HBr HCl HF

Solution Steps

The boiling point of a substance is influenced by the strength of its intermolecular forces. The stronger the intermolecular forces, the higher the boiling point. The main types of intermolecular forces are:

1. London dispersion forces: Present in all molecules, but stronger in larger, more polarizable molecules.
2. Dipole-dipole interactions: Occur in polar molecules.
3. Hydrogen bonding: A special type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like nitrogen, oxygen, or fluorine.

• HI: Has London dispersion forces and dipole-dipole interactions. It is the heaviest and most polarizable molecule among the given options.
• HBr: Has London dispersion forces and dipole-dipole interactions. It is less polarizable than HI.
• HCl: Has London dispersion forces and dipole-dipole interactions. It is less polarizable than HBr.
• HF: Has London dispersion forces, dipole-dipole interactions, and hydrogen bonding due to the presence of hydrogen bonded to fluorine.

• HF: The presence of hydrogen bonding makes HF have very strong intermolecular forces compared to the others, which only have dipole-dipole interactions and London dispersion forces.
• HI, HBr, HCl: Among these, HI has the strongest London dispersion forces due to its larger size and higher polarizability.

Final Answer