Question

Give a reason for the higher boiling point of ethanol in comparison to methoxymethane.

Answer 1

Hydrogen Bond:

• The bond between the hydrogen atom of one molecule and the electronegative atom [Oxygen$\left(\mathrm{O}\right)$, Nitrogen$\left(\mathrm{N}\right)$ or Fluorine$\left(\mathrm{F}\right)$] of another molecule is called intermolecular hydrogen bonding.
• Compared to Ionic and covalent bonds, these are weaker but stronger than Van der Waal's forces.
• Hydrogen bonds are intermolecular forces.
• When a molecule has intermolecular hydrogen bonding, it requires more energy to break i.e., a high boiling point is required.
• Ethanol is alcohol whereas methoxy methane is an ether.
• Both have the same molecular formula but different structures due to different functional groups in them.
• Ethanol$\left({\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}\right)$ has $-\mathrm{OH}$ a group that undergoes intermolecular hydrogen bonding where it is absent in methoxy methane$\left({\mathrm{C}}_2{\mathrm{H}}_6\mathrm{O}\right)$.

Therefore due to the presence of intermolecular hydrogen bonding, ethanol $\left({\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}\right)$ has a higher boiling point than methoxy methane$\left({\mathrm{C}}_2{\mathrm{H}}_6\mathrm{O}\right)$.