Question

Why ethanol has higher boiling point than ethane ?

Answer 1

The molecules of ethane are joined together by weak van der waals force of attraction while ethanol are held by stronger intermolecular hydrogen bonding. Therefore, ethanol has higher boiling point than ethane.

Answer 2

Ethanol has higher molecular mass than ethane and it also contains -OH group. So the ethanol molecules are associated with hydrogen bonding. But in ethane molecule only van der waal force is operative. So in case of ethanol higher thermal kinetic energy is needed to tear the greater molecular association and that is why it has got higher boiling point than ethane.