Physics – 2.2.3 Melting, boiling and evaporation | e-Consult

The boiling point of water is higher than the melting point because more energy is required to overcome the intermolecular forces in the liquid state compared to the solid state. Water molecules in the solid (ice) are held together by strong hydrogen bonds. Melting requires energy to break these bonds and allow the molecules to move more freely as a liquid. In the liquid state, water molecules are still held together by hydrogen bonds, although they can move past each other. Boiling requires significantly more energy to completely overcome these hydrogen bonds and allow the molecules to escape into the gaseous state. This is because the hydrogen bonds are relatively strong, requiring a substantial amount of energy to break. Therefore, a higher energy input is needed to raise the temperature of water from the liquid to the gaseous state (boiling) compared to raising it from the solid to the liquid state (melting). The energy required to break the hydrogen bonds in the liquid state is greater than the energy required to break the bonds in the solid state.