. Why do compounds having hydrogen bonding have high melting and boiling points
The compounds having hydrogen bonding show abnormally high melting and boiling points. The high melting and boiling point of the compound containing hydrogen bonds is due to the fact that some extra energy is needed to break these bonds.
i. The unusually high boiling point of hydrogen fluoride among the halogen acid is due to the existence of hydrogen bonding.
ii. H2O is a liquid whereas H2S, H2Se and H2Te are all gases at ordinary temperature. In water, hydrogen bonding causes linkages in the water molecules which result in the boiling point of water is more than that of the other compounds.
iii. Ammonia has a higher boiling point than PH3 because there is hydrogen bonding in NH3 but not in PH3.
iv. Ethanol has a higher boiling point than diethyl ether because there is hydrogen bonding in the ethanol.