Question

The molecular mass of butanol, C4H9OH, is 74.14; that of ethylene glycol, CH2(OH)CH2OH, is 62.08, yet their boiling points are 117.2 °C and 174 °C, respectively. Explain the reason for the difference

Answer 1

Butanol has one -OH group in it which is used to form intermolecular H-bonds with other molecule of butanol. Ethylene glycol is a diol compound. Such that it has two -OH groups which can form strong H-bonds in an intermolecular fashion. Breaking these H-bonds require energy. So as the number of H-bond forming groups increase, the energy required to break these bonds increase and so the boiling point also goes up. Thus thylene glycol has a higher boiling point than butanol.