cohesion

Examples of cohesion in the following topics:

• Surface Tension

  • The tendency of the surface of a liquid to resist a force and behave like a membrane and is a result of cohesion between liquid molecules.
  • This effect is a result of cohesion of the molecules of the liquid causing the surface of the liquid to contract to the smallest area possible.
  • The contact angle is measured in the liquid and depends on the relative strength of cohesive forces in the liquid and adhesive forces between the liquid and interface materials.
  • If the cohesive forces are greater than the adhesive forces, the resulting contact angles will be large and will form a more circular drop .
  • When a water droplet forms on a leaf, the cohesive forces between the water molecules are greater than the adhesive forces between the water and leaf surface.

• Surface Tension and Capillary Action

  • Attractive forces between molecules of the same type are called cohesive forces.
  • Liquids can, for example, be kept in open containers because cohesive forces hold the molecules together.
  • In this section we examine effects of cohesive and adhesive forces in liquids.
  • This property is caused by cohesion of similar molecules and is responsible for many of the behaviors of liquids.
  • The cohesive forces among liquid molecules are responsible for the phenomenon of surface tension, as shown in .

• Latent Heat

  • Energy is required to melt a solid because the cohesive bonds between the molecules in the solid must be broken apart so that the molecules can move around at comparable kinetic energies; thus, there is no rise in temperature.
  • Work is done by cohesive forces when molecules are brought together.

• Molecular Transport Phenomena

  • For example, temperature and cohesive and adhesive forces all affect values of D.