Discussing Issues Relating to Oceanography

A substance melts when its molecules move apart and have a “wider range” of motion than is possible in the solid state (Yong and Wai 197).
During boiling or conversion from liquid to vapor state, energy is not only required for overcoming the attractive forces between molecules but also for expanding the vapor against the atmospheric pressure. The energy required for this process is called latent heat of vaporization. In this case, too, the kinetic energy of the molecules remains constant.
Latent heat of melting only breaks down a few bonds between molecules while latent heat of fusion breaks down all the bonds. Moreover, during vaporization, the molecules are reorganized more vigorously than during melting. Therefore, the latent heat of vaporization is greater than the latent heat of fusion. For example, the latent heat of melting of ice (6.0×103 Jmol-1) is only 15% of the latent heat of vaporization (Adkins 79).
This is because of the strong intermolecular forces between water molecules. Water molecules are polar because of charge separation between the oxygen and hydrogen atoms, where oxygen atoms are partially negative and hydrogen atoms are partially positive. Because of the presence of positive and negative poles, each water molecule bonds with other water molecules. This leads to strong intermolecular hydrogen bonding. The boiling point and the freezing/melting point of water are higher than that of other compounds of similar makeup, such as H2S, H2Te and H2Se, because larger amounts of heat are required to overcome the strong hydrogen bonds in water compared to other compounds where hydrogen bonds are absent. Thus, the freezing point of water (which is equal to the melting point) is 100ºC higher than expected and the boiling point is 200ºC higher than expected (Spencer, Bodner, and Rickard 333).