Analysis of influencing factors of interfacial tension

Definition of interfacial tension

Interfacial tension is a tension phenomenon generated at the interface between liquid and air or other substances. It is the manifestation of the interaction force between liquid molecules at the interface. Interfacial tension, also known as the surface tension of a liquid, is the tension phenomenon at the interface between liquid and air. From a numerical point of view, the interfacial tension is equal to the interface rising energy per unit area, or equal to the specific interface energy. At the interface between solid and liquid, the interfacial tension is called solid-liquid interfacial tension, which is equal to the free energy of the solid surface. The solid-liquid interface energy of different materials is different. Metals and inorganic substances have higher surface energy and are called high-energy surfaces, while plastics and other organic substances have lower surface energy and are called low-energy surfaces.

Factors affecting interfacial tension

Interfacial tension is affected by many factors, including intrinsic and extrinsic factors.

Internal factors:

• Liquid Type: Inorganic liquids generally have greater surface tension than organic liquids. In organic liquids, molecules containing elements such as nitrogen and oxygen usually have larger surface tensions, while liquids containing elements such as fluorine and silicon have smaller surface tensions.

• Molecular Weight: Liquids with larger molecular weights generally have greater surface tension.

• Presence of solutes: Surface tension in aqueous solutions is affected by solutes. Aqueous solutions containing inorganic salts have a larger surface tension, while aqueous solutions containing organic matter have a smaller surface tension.

External factor:

• Temperature: The increase in temperature will cause the surface tension to decrease. This is because as the temperature increases, the kinetic energy of the molecules increases and the aggregation of molecules on the interface decreases, thereby reducing the interfacial tension.

• Pressure: Pressure is not directly related to surface tension, that is, changes in pressure will not cause changes in surface tension.

in conclusion

Interfacial tension is the manifestation of the interaction between liquid molecules at the interface. It is closely related to the properties of the liquid and external conditions. Intrinsic factors such as liquid type, molecular weight, and presence of solutes will affect the magnitude of interfacial tension, while external factors such as temperature and pressure will affect changes in interfacial tension. Understanding the influencing factors of interfacial tension is of great significance to understanding the behavior of liquids and its applications in materials science, chemical engineering and other fields.