Surface Energy

Introduction

Surface energy is potential energy, applicable for liquid molecules where the molecules stand on the same surface as the liquid substances. The surface energy characteristically decreases when the molecules try to settle down to the bottom layer of the liquid surface. In the case of surface energy, equivalent attractive forces are commonly present between the solid materials and the surface at the same time.

What is Surface Energy?

Surface energy can be defined as energy where an equivalent attractive force is present between the solid molecules and the surface molecules. The surface energy commonly differs from the high note to the low note and vice versa. According to the characteristics of surface energy, it cannot be measured as it arises during the interaction between surface molecules and solid molecules in real-time (Darwish et al. 2022).

In the case of surface energy, the surface of the liquid is commonly called a stretched membrane. During the generation of surface energy, the surface stores some potential energy when it is present in the liquid surfaces. Under these circumstances, the surface energy is known as the surface free energy.

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Surface energy can also be described as a measure for quantifying excess energy, present in the solid or liquid surfaces in a bulk. This energy is commonly used during the adhesion and wetting processes between materials. Although it quantifies these processes, it cannot be measured quantitatively every time.

In a bulk forms of materials, the atoms are generally balanced and stable while creating interactions and bonds between themselves. During this process, the phenomenon of surface energy is generated between the surface and the materials as a relative measurement. In most of the cases, surface energy is not favourable for complete boding and in most cases, they result in an incomplete bonding between the surface and the material in real-time.

For example, if a metal ball is thrown on a certain surface, it creates surface energy as it is being pulled by the gravity of the floor. In this instance, when surface energy is generated, it also gives away surface tension at the same time. The surface of the materials like glasses, metals, ceramics and materials can generate surface energy as they hold stronger bonds in terms of the interaction between atoms.

For example, bonds like iconic bond, metallic bond and covalent bond are capable of generating surface energy in real-time.

Formula for Surface Energy

Surface energy is denoted with the SI unit of N/m and the dimension of surface energy is $\mathrm{[MT^{-2}]}$. In some instances, ‘surface energy is also measured with the unit of $\mathrm{mJ/M^{2}}$. For example, the surface energy of glass is 83.4 $\mathrm{mJ/M^{2}}$, for water it is 73 $\mathrm{mJ/M^{2}}$, for copper 1650 $\mathrm{mJ/M^{2}}$ and for lead, the surface energy is 442 $\mathrm{mJ/M^{2}}$.

The dimensional formula for surface energy is $\mathrm{[M^{1}L^{0}R^{-2}]}$. Hare, M means the mass of the material, L denotes the Length of the material and T denotes Time. For example, if the derivation of surface energy, is surface energy (E) = energy $\mathrm{\times [area]^{-1}...(1)}$, then the energy will be equal to the $\mathrm{force\:\times \:displacement=m\times a\times x\:displacement}$. Then, the energy will be $\mathrm{[M^{1}\times M^{0}L^{1}T^{-2}\times L^{1}]}$. After that, when the dimensional formula is applied, the equation stands at energy = $\mathrm{[M^{1}L^{2}T^{-2}]...(2)}$.

Then the dimensional formula will be $\mathrm{[M^{0}L^{0}T^{0}]...(3)}$. Therefore, the dimensional representation of the surface energy will be $\mathrm{[M^{1}L^{2}T^{-2}]}$.

Relation between Surface Energy and Surface Tension

Surface energy and surface tension are interrelated, based on the possibility of an object touching a certain surface in real-time. Mathematically, they are related through the formula of

$$\mathrm{Surface\:energy=Energy/Area=Joule/m^{2}=Newton\times m/m^{2}=Force/Length=Surface\:Tension}$$

Therefore, it outlines that during the generation of surface energy, energy is divided by area and then it equals the joules divided by mass and then Newton multiplied by mass. Here, the force is divided by the length and finally, it relates to the surface tension.

For example, if a rectangular wire framework is taken and it is dipped into a frame of soap solution, then two surfaces will be created during this operation. Let us take that T denotes the soap solution and L denotes the wire framework.

So, the exerted force between the surface and the wire will be T $\mathrm{\times}$ L, therefore the total force will be wire = 2TL. Here, the surface film experiences both the surface energy as well as the surface tension in this experiment

Conclusion

Surface energy can commonly be found in the outermost area of a material in which the atoms are not bonded in an immediate neighbourhood. This commonly takes place because the bonded atoms surround the physical structure of the atoms. However, before touching the surface, the molecules of the materials are split-open and destroy the atoms in the outer end of the material.

FAQs

Q.1. Which force is responsible for the generation of surface energy?

Ans. The cohesive force in the liquid molecules is mostly responsible for the generation of surface energy. Here, surface energy is formed when the work done per unit area is produced within a new surface.

Q.2. Which factors affect surface energy the most?

Ans. The cutting of solid bodies into pieces can affect the formation of surface energy the most. When it is cut into pieces, they disrupt the bonds and increase the surface area, eventually increasing the surface energy in the process.

Q.3. Which real-time material has the highest amount of surface energy?

Ans. Metal is a real-time material that has a high amount of surface energy as they are eligible to perform well in different environmental conditions and temperatures.