What Is Surface Energy?

In the case of constant temperature, constant pressure, and constant composition, the non-volume work on the material is required to increase the surface area of the system reversibly. Another definition of surface energy is the extra energy of surface particles relative to internal particles.

The environment of particles on the surface of the object and the particles inside are different, so they have different energies. For example, in a liquid, each ion is evenly surrounded by neighboring particles, so that the attractive forces from different directions cancel each other out and are in a state of force equilibrium. The particles on the surface of the liquid are different. The outside of the liquid is a gas, and the density of the gas is less than that of the liquid. Therefore, the surface ions are less attracted by the gas molecules, while the particles inside the liquid are more attractive. The forces in each direction are not balanced. In this way, the surface molecules are subjected to a tensile force directed toward the interior of the liquid, so the liquid surface tends to shrink to a minimum automatically.

If you want to move the particles inside the liquid to the surface, you need to overcome the inward pulling force and do work. When these migrated particles form a new surface, this part of the work consumed is transformed into the potential energy of the particles in the surface, which increases the total energy of the system. This part of the surface energy more than the internal particles is called surface energy.

Practice has proved that surface energy exists not only on the surfaces of liquids and gases, but also on any two-phase interface. In colloidal dispersion systems, dispersive particles have a large total

Can be used to calculate liquid contact angle