Why boiling point of ethanol is higher in comparison to methoxymethane
The Correct Answer and Explanation is:
The boiling point of ethanol is higher than that of methoxymethane due to the difference in intermolecular forces between the two substances.
Ethanol (C₂H₅OH) contains a hydroxyl group (-OH), which allows the molecules to form hydrogen bonds. Hydrogen bonding is a strong type of dipole-dipole interaction that occurs when a hydrogen atom, which is covalently bonded to a highly electronegative atom like oxygen, interacts with the lone pairs of electrons on another electronegative atom. In the case of ethanol, the oxygen in the hydroxyl group is highly electronegative, and it forms hydrogen bonds with the hydrogen atoms of neighboring ethanol molecules. These hydrogen bonds are strong, requiring a substantial amount of energy to break them, which results in a higher boiling point.
Methoxymethane (CH₃OCH₃), on the other hand, contains an oxygen atom bonded to two methyl groups (-CH₃). The oxygen in methoxymethane can engage in dipole-dipole interactions, as oxygen is electronegative, but it cannot form hydrogen bonds because the molecule does not have an -OH group. Instead, the interactions between methoxymethane molecules are weaker van der Waals forces (London dispersion forces) and dipole-dipole interactions. These intermolecular forces are less substantial than the hydrogen bonds present in ethanol, so methoxymethane requires less energy to separate its molecules, resulting in a lower boiling point.
In summary, ethanol has a higher boiling point than methoxymethane because it forms stronger hydrogen bonds, which require more energy to break. Methoxymethane, with only dipole-dipole and van der Waals forces, has weaker intermolecular interactions, leading to a lower boiling point.
