Introduction to Adhesion and Cohesion
In the study of molecular interactions, adhesion refers to the attractive force between dissimilar molecules, causing them to stick together. Conversely, cohesion is the force that holds similar molecules together. These forces are responsible for various phenomena we observe in everyday life, such as water droplets forming on surfaces (adhesion) and water molecules sticking together to create surface tension (cohesion).
Differences Between Adhesion and Cohesion
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FAQs on Adhesion vs. Cohesion: Understanding Molecular Interactions
1. What is the difference between adhesive and cohesive forces?
Adhesive forces cause dissimilar molecules to attract and stick together, while cohesive forces cause similar molecules to attract each other.
2. Can you provide examples of adhesive and cohesive forces?
An example of adhesive force is water spreading on a glass surface. An example of cohesive force is water forming droplets due to intermolecular attraction.
3. Are adhesive forces stronger than cohesive forces?
The strength of adhesive and cohesive forces varies depending on the substances involved. For instance, water's adhesive forces with glass are stronger than its cohesive forces, causing it to climb up the sides of a glass container.
4. How do adhesive and cohesive forces relate to transpiration pull in plants?
Adhesion helps water molecules stick to the walls of xylem vessels, while cohesion allows water molecules to stick to each other. Together, they facilitate the upward movement of water from roots to leaves.
5. Is cement adhesive or cohesive?
Cement exhibits adhesive properties, bonding to various materials like stone, brick, and metal, and cohesive properties, allowing it to maintain its form as a solid mass.
6. What are the seven main properties of water?
The seven main properties of water are polarity, cohesion, adhesion, high specific heat, high heat of vaporization, solvent abilities, and surface tension.
7. What is meant by adhesive force?
Adhesive force refers to the attractive force between dissimilar molecules or surfaces, causing them to stick together.
8. Is water adhesive or cohesive?
Water exhibits both adhesive and cohesive properties. Its molecules stick to other substances (adhesion) and to each other (cohesion), which is evident in phenomena like capillary action and surface tension.
9. What is the angle of contact?
The angle of contact, or contact angle, is the angle formed between the tangent to the liquid surface and the solid surface with which it is in contact, indicating the wettability of the surface by the liquid.
10. Can you provide a real-life example of adhesion?
A real-life example of adhesion is the way water droplets cling to the surface of a leaf due to the attraction between water molecules and the leaf's surface.
