Cohesive and Adhesive Forces

Answer: Surface tension is caused by the force of cohesion between molecules of the liquid. At the surface, molecules do not have any other molecules like them on all sides, so they are more likely to cohere with those directly adjacent to the surface.

Answer: Cohesion helps water molecules adhere to glass or plant tissue, while adhesion helps them stay together. Water can travel up the tube at a higher rate if the tube has a smaller diameter. Meniscuses of liquids in glasses are also caused by cohesion and adhesion.

Answer: Molecular particles (atoms, molecules, or ions) are held together by strong, cohesive forces, resulting in little void space and very low compressibility and thermal expansion. Solids are generally dense, and their density does not vary much with temperature. On the other hand, liquids tend to be more cohesive than disruptive.

Answer: Because they hold the molecules of the sample close together, cohesive forces, or forces resulting in cohesion, are generated between like molecules. The strong, cohesive forces cause this phenomenon of surface tension at the surface of a liquid.

Answer: The two major applications of the Stokes’ Law are as follows:

• Settling of sediment into the freshwater
• Measurement of the viscosity of the fluid