Determination of interfacial tension and surface tension

Interfacial tension and surface tension is an important phenomenon of the interaction between liquids and solids or liquids and liquids, and it has a wide range of applications in various fields. In order to accurately measure interface and surface tension, various methods have been developed. This article will focus on three commonly used determination methods: maximum bubble pressure method, drip weight method and capillary lift method.

1. Maximum bubble pressure method

The maximum bubble pressure method is a commonly used method for measuring the surface tension of liquids. It is based on the process of bubble formation and gradual expansion in a capillary tube, and calculates the surface tension by measuring the pressure difference when the bubble expands at its maximum. In the experiment, a test tube containing liquid is connected to a capillary tube, and the liquid rises in the capillary tube by gradually reducing the air pressure to form bubbles. When the bubble reaches its maximum, its radius of curvature is the smallest, and the pressure difference is the largest at this time. By measuring the maximum pressure difference displayed by the pressure gauge, combined with known parameters such as air pressure, the surface tension can be calculated.

2. Capillary lift method

The capillary rise method is another method for measuring surface tension. It uses the relationship between the rising height of the liquid in the capillary and the surface tension to measure. In the experiment, a clean, grease-free capillary is immersed in the liquid to be tested, and the liquid rises to an equilibrium height in the capillary. By measuring this rising height as well as some liquid parameters, the surface tension can be calculated. This method is suitable for comparing the surface tension of different liquids, but attention needs to be paid to the handling of the capillary and the selection of the liquid to ensure the accuracy of the experiment.

3. Drop weight method

The drip weight method is a method of calculating the surface tension by measuring the weight of the droplet and other parameters. In this method, the droplet is dropped under control, and there is a certain relationship between its weight and the surface tension. In the experiment, parameters such as the weight of the droplet and the rate of droplet formation are measured, and then the surface tension is calculated by the corresponding formula. This method is more suitable in some cases, but it is also necessary to pay attention to the influence of factors such as the degree of volatilization of the droplet.

Conclusion

Interfacial tension and surface tension are important qualities in liquid interface phenomena, and there are various methods for their determination. Maximum bubble pressure method, capillary lift method and drip weight method are three commonly used methods, each of which has advantages and scope of application. In practical applications, choosing an appropriate method requires consideration of factors such as experimental conditions, liquid properties, and required accuracy. The application of these methods contributes to a deep understanding of interface and surface phenomena and provides important experimental data in the fields of materials science, chemical engineering, etc.