Final answer:
Pentane has a higher boiling point than methyl butane (2-methylbutane) because it has a straight-chain structure, which allows for stronger London dispersion forces compared to the branched structure of 2-methylbutane.
Step-by-step explanation:
When comparing the boiling points of methyl butane (also known as 2-methylbutane) and pentane, we must consider intermolecular forces at play. Both molecules are alkanes and are nonpolar, which means London dispersion forces are the primary intermolecular forces affecting their boiling points. These forces increase with the molecular mass and the surface area contact between molecules.
Pentane is a straight-chain alkane with a systematic structure that allows for more extensive contact between molecules, resulting in stronger London dispersion forces. On the other hand, methyl butane (2-methylbutane) has a more compact, branched structure which hinders this stacking and leads to weaker London dispersion forces. Thus, pentane has a higher boiling point than methyl butane. The boiling points (in °C) of the respective compounds are pentane (36.1) > 2-methylbutane (-11.7), confirming this analysis.