The enthalpy of fusion is influenced by the strength of intermolecular forces present between molecules.

Enthalpy of fusion refers to the amount of energy necessary to convert a solid into a liquid at its melting point. This energy is utilized to overcome the intermolecular forces that hold the molecules together in the solid state. The strength of these forces is contingent upon the type of molecule and its structural characteristics.

For instance, water exhibits a high enthalpy of fusion due to the presence of strong hydrogen bonds between its molecules. These bonds arise from electrostatic attractions between the positively charged hydrogen atoms of one water molecule and the negatively charged oxygen atoms of another. Because these hydrogen bonds are relatively strong, a significant amount of energy is required to break them, resulting in the melting of ice.

In contrast, methane possesses a low enthalpy of fusion, as it is held together by weak van der Waals forces. These forces are generated by temporary dipoles in the electron clouds of the molecules, which lead to transient attractions. Since these forces are comparatively weak, less energy is needed to overcome them and melt the solid.

In summary, the enthalpy of fusion serves as an important indicator of the strength of intermolecular forces among molecules. It can be utilized to predict the melting and boiling points of various substances, along with their physical properties such as viscosity and surface tension.