Question

The contact angle between water and glass is 0°. When water is poured in a glass to the maximum of the capacity, the water surface is convex upward. The angle of contact in such a situation is more than 90°. Explain.

Answer 1

Hint:To respond to this question, we must first comprehend the concept of surface tension. Surface tension is a feature of a liquid surface that manifests itself as a stretched elastic membrane. The roughly spherical shape of little liquid drops and soap bubbles are examples of this phenomenon.Certain insects can stand on the surface of water due to this characteristic.

Complete answer:
Due to surface tension, the liquid's surface acts as a stretched membrane, as mentioned in the suggestion section.Surface tension is determined by the forces of attraction between particles within a liquid, as well as the forces of attraction of solids, liquids, and gases in contact with it.

The work or energy necessary to remove the surface layer of molecules in a unit area is roughly equivalent to the energy responsible for the phenomena of surface tension. As a result, even if more water is poured into it than the glass rim level, the stretched water surface that keeps the glass rim in place grows convex upward due to surface tension adhesion, and the contact angle between the water and the glass increases to more than 90°.

Note:The zero degrees angle of contact between water and the glass is employed if the water level is below the rim level of the bottle. In some odd conditions, the angle of touch might shift.The surface tension of water can also support a razor blade. The razor blade does not float; if pushed through the water's surface, it sinks.