The boiling point of a substance is influenced by the strength and type of intermolecular forces between its molecules. In the case of ethanoic acid (acetic acid) and methanoic acid (formic acid), the difference in boiling points can be attributed to the variation in intermolecular forces.
Ethanoic acid (CH3COOH) has a higher boiling point than methanoic acid (HCOOH) primarily due to the presence of stronger intermolecular hydrogen bonding in ethanoic acid. Hydrogen bonding is an attractive force that occurs between a hydrogen atom bonded to an electronegative atom (in this case, oxygen or nitrogen) and another electronegative atom in a different molecule.
In ethanoic acid, the presence of two hydrogen atoms bonded to oxygen atoms (–OH) allows for intermolecular hydrogen bonding. The hydrogen atoms of one ethanoic acid molecule can form hydrogen bonds with the oxygen atoms of neighboring ethanoic acid molecules. These hydrogen bonds are relatively strong and require more energy to break, resulting in a higher boiling point for ethanoic acid.
On the other hand, methanoic acid has only one hydrogen atom bonded to an oxygen atom. While it can form hydrogen bonds with other methanoic acid molecules, the presence of only one hydrogen bond per molecule leads to weaker intermolecular forces compared to ethanoic acid. As a result, methanoic acid has a lower boiling point than ethanoic acid.
In summary, the difference in boiling points between ethanoic acid and methanoic acid can be attributed to the presence of stronger intermolecular hydrogen bonding in ethanoic acid, which requires more energy to overcome and leads to a higher boiling point.