Mercury as a Non-Wetting Liquid

Mercury is known as a non-wetting liquid because it does not wet the surface it comes into contact with. This property of mercury can be attributed to cohesion rather than other factors such as adhesion, viscosity, or surface tension.

Cohesion:
- Cohesion is the force of attraction between molecules of the same substance.
- In the case of mercury, the cohesive forces between its own molecules are much stronger than the adhesive forces between the mercury and other substances.
- This strong cohesion prevents mercury from spreading out or wetting the surface it encounters.

Adhesion:
- Adhesion is the force of attraction between molecules of different substances.
- While adhesion plays a role in the wetting of a liquid, it is not the primary factor for mercury's non-wetting behavior.
- The adhesive forces between mercury and most substances are relatively weak compared to the cohesive forces within the mercury itself.

Viscosity:
- Viscosity is a measure of a fluid's resistance to flow.
- Although viscosity can affect how a liquid spreads or wets a surface, it is not the primary reason for mercury's non-wetting behavior.
- Even though mercury has a relatively high viscosity, it still does not wet most surfaces due to its strong cohesion.

Surface Tension:
- Surface tension is the tendency of a liquid's surface to minimize its surface area.
- Surface tension is related to both cohesion and adhesion.
- While surface tension can influence wetting behavior, it is not the primary reason for mercury's non-wetting property.
- The strong cohesive forces in mercury outweigh the effects of surface tension, leading to non-wetting behavior.

Conclusion:
In conclusion, the property of mercury as a non-wetting liquid can be attributed to its strong cohesive forces. While adhesion, viscosity, and surface tension may have some influence, it is the cohesion between mercury molecules that prevents it from wetting most surfaces.