Final answer:
Physical properties like boiling points correlate with the strength and type of intermolecular forces, with hydrogen bonding typically leading to higher boiling points, as observed in substances such as benzoic acid compared to naphthalene.
Step-by-step explanation:
Physical properties such as boiling points are influenced by the strength of a substance's intermolecular forces. Substances with higher boiling points generally have stronger intermolecular interactions. Naphthalene, an aromatic hydrocarbon, displays London dispersion forces and has a moderate boiling point. Benzoic acid, on the other hand, can engage in hydrogen bonding due to its carboxylic acid group, leading to a higher boiling point despite its similar molar mass compared to naphthalene.
The shape of molecules also plays a significant role as it affects the surface area available for intermolecular interactions. Linear or elongated molecules tend to have stronger dispersion forces due to greater surface contact, while compact shapes correspond to weaker forces. This is observed when comparing the boiling points of isomeric hydrocarbons, where more extended shapes result in higher boiling points. The mentioned substances illustrate these concepts, as naphthalene has a flat planar structure allowing for more surface contact between molecules, while benzoic acid's ability for hydrogen bonding elevates its boiling point beyond that expected from its molecular mass and structure alone.