Definition of interfacial tension
Interfacial tension is a tension phenomenon generated at the interface between liquid and air or other substances, and it is the reflection of the interaction force between liquid molecules at the interface. Interfacial tension, also known as the surface tension of a liquid, is the phenomenon of tension at the interface between a liquid and air. From the 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 solid and liquid interface, the interfacial tension is called the 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, the surface energy of metals and inorganic substances is higher, which is called a high-energy surface, while the surface energy of organic substances such as plastics is lower, which is called a low-energy surface.

Analysis of influencing factors of interfacial tension

Influencing factors of interfacial tension
Interfacial tension is affected by many factors, including internal factors and external factors.

Internal factors:

Type of liquid: 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 tension, while liquids containing elements such as fluorine and silicon have smaller surface tension.

Molecular weight: Liquids with higher molecular weight usually have higher surface tension.

Solute presence: Surface tension in an aqueous solution is affected by the solute. The surface tension of aqueous solution containing inorganic salt is higher than that of aqueous solution containing organic matter.

External factors:

Temperature: An increase in temperature will lead to a decrease in surface tension, because as the temperature increases, the molecular kinetic energy increases, and the aggregation of molecules at the interface decreases, thus reducing the interfacial tension.

Pressure: There is no direct relationship between pressure and surface tension, that is, changes in pressure will not cause changes in surface tension.

Analysis of influencing factors of interfacial tension

conclusion
Interfacial tension is the performance of the interaction between liquid molecules at the interface, which is closely related to the properties of liquid and external conditions. Internal factors such as liquid type, molecular weight and solute presence affect the interfacial tension, while external factors such as temperature and pressure affect the change of interfacial tension. Understanding the factors affecting interfacial tension is important for understanding the behavior of liquids and their applications in materials science, chemical engineering and other fields.