When you half-fill a glass with mercury, the mercury curls...

Name: Problem 20, Chapter 12: Physics: A Conceptual World View
Uploaded: 2020-06-13T02:50:20-08:00
Duration: 38 s
Channel: Mayukh Banik
Description: When you half-fill a glass with mercury, the mercury curls down where it meets the glass. What can you conclude about the relative strengths of the inter atomic forces between the mercury atoms and the adhesive forces between the mercury atoms and the glass? (Caution: Mercury is toxic and should not be handled.)

When you half-fill a glass with mercury, the mercury curls down where it meets the glass. What can you conclude about the relative strengths of the inter atomic forces between the mercury atoms and the adhesive forces between the mercury atoms and the glass? (Caution: Mercury is toxic and should not be handled.)

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Key Concepts

Cohesive Forces

Cohesion refers to the attractive forces between like particles—in this case, the mercury atoms. These forces are responsible for the tendency of mercury to stick together, resulting in a curved or convex surface when in contact with another material. The strong cohesive forces in mercury cause the liquid to minimize contact with the container walls rather than spreading out widely.

Adhesive Forces

Adhesion is the attraction between different substances, such as the mercury and the glass. In this scenario, the relatively weak adhesive forces between mercury and glass compared to the stronger cohesive forces among the mercury atoms lead to less wetting of the glass surface. This is why the mercury curls downward at the edge of the glass.

Surface Tension and Meniscus Formation

Surface tension, which is a consequence of strong cohesive forces, is the property of a liquid's surface that makes it contract and resist external force. In mercury, high surface tension results from the strong interatomic attractions. This causes the liquid to form a convex meniscus and minimizes the area in contact with the glass, clearly displaying the balance between cohesive and adhesive forces.

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