Final answer:
Propanoic acid has a higher boiling point than methyl acetate due to its ability to form hydrogen bonds. For the other compounds, 2-methylpropane will have the lowest boiling point, followed by ethyl methyl ether, and acetone will have the highest due to their molecular polarity and intermolecular interactions.
Step-by-step explanation:
The substance with the higher boiling point between propanoic acid (CH3CH2COOH) and methyl acetate (CH3COOCH3) is propanoic acid. This is due to the ability of propanoic acid to form hydrogen bonds because of the presence of the -COOH group, which is much stronger than the dipole-dipole interactions present in methyl acetate. Hydrogen bonding significantly increases the boiling point as more energy is required to break these strong intermolecular forces. Regarding the order of increasing boiling points for the compounds ethyl methyl ether (CH3OCH2CH3), 2-methylpropane [isobutane, (CH3)2CHCH3], and acetone (CH3COCH3), we can predict that 2-methylpropane will have the lowest boiling point because it is mostly nonpolar. Next is ethyl methyl ether, which has some polar C-O single bonds leading to moderate dipole-dipole interactions. Acetone will have the highest boiling point due to the polar C=O double bond contributing to a larger dipole moment and stronger dipole-dipole attractions.