Chemistry
Chemistry
Problem
n-Pentane boils at 36.1 °C, whereas neopentane boils at 9.5 °C even though both share the molecular formula C₅H₁₂. Explain the difference in boiling points in terms of intermolecular attractions.Intuitive explanation
The key here is molecular shape and surface area contact. Both molecules are nonpolar hydrocarbons, so their intermolecular forces are London dispersion forces—which depend entirely on how much surface area the molecules can touch each other. n-Pentane is a long, stretched-out chain that allows many points of contact between neighboring molecules, creating stronger dispersion forces. Neopentane is compact and spherical, minimizing surface contact and weakening intermolecular attractions. More surface area means stronger dispersion forces and a higher boiling point.
Intuitive explanation
The key here is molecular shape and surface area contact. Both molecules are nonpolar hydrocarbons, so their intermolecular forces are London dispersion forces—which depend entirely on how much surface area the molecules can touch each other. n-Pentane is a long, stretched-out chain that allows many points of contact between neighboring molecules, creating stronger dispersion forces. Neopentane is compact and spherical, minimizing surface contact and weakening intermolecular attractions. More surface area means stronger dispersion forces and a higher boiling point.