cohesion and adhesion.pptx

a short knowledge of cohesion and adhesion differences

1. By Samjhana Thapa Cohesion and Adhesion

2. Cohesion Attraction between same molecules - Like water is attracted to water molecules Hold hydrogen bond together to create surface tension

3. Some examples of cohesion Insect walk on water Water droplet before falling down Glass is fill up with water beyond top Oil drops falling down

4. Adhesion Attraction between different molecules- water molecules stick to other substances Attraction can be due H-bond, polar attraction, dipole-dipole attraction

5. Some examples of adhesion water droplets at the tip of leafs Water drops at the spider web

6. Capillary action It occurs when adhesive forces is stronger than cohesive force concave miniscus in water Convex miniscus in mercury

7. Importance of cohesion and adhesion helps to transport water in plants Important role in water based process including movement of water to top of trees and drainage of tears from tear duct in corner of eyes

8. Differences between adhesion and cohesion Cohesion Adhesion - Attraction in same molecule - Attraction between different molecule - caused by hydrogen bonding and vander walls - caused by electrostatic force - strong force of cohesion cause water droplet to form on any surface - Strong force of adhesion cause liquid to spread on solid surface