Final answer:
The state of butane as a gas and butanol as a liquid at room temperature is due to the difference in their intermolecular forces: butane has weak dispersion forces while butanol has strong hydrogen bonding.
Step-by-step explanation:
The difference in physical states between butane (C4H10) and butanol (C4H9OH) at room temperature and pressure can be attributed to the different intermolecular forces present in these compounds. Butane, which is a gas at room temperature and pressure, consists of molecules that are nonpolar and interact through relatively weak dispersion forces. On the other hand, butanol contains an hydroxyl group (OH), which provides the capability for hydrogen bonding. This type of intermolecular force is significantly stronger than the dispersion forces in butane and leads to a higher boiling point, making butanol a liquid at room temperature.
Liquids have molecules that are closer together than gases, and the attractive forces between them must be strong enough to keep them in the liquid state. Butanol's ability to form hydrogen bonds increases the amount of energy necessary to break these intermolecular attractions, thus requiring a higher temperature to convert to a gas. In contrast, the interactions in butane are weaker, allowing it to exist as a gas under room temperature and pressure because less energy is needed to overcome these dispersive forces.