Answer to Question #332561 in General Chemistry for micheal

Question

a. Define the terms viscosity, capillary action and surface tension.

b. How do the viscosity and surface tension of liquids change as intermolecular forces become stronger? Explain.

c. How do the viscosity and surface tension of liquids change as temperature increases? Explain.

d. Using the Kinetic Particulate theory explain the compressibility of liquids .

Answer 1

(a) Viscosity is the resistance of a fluid (liquid or gas) to a change in shape or movement of neighbouring portions relative to one another. Viscosity denotes opposition to flow.

Capillary action (sometimes called capillarity, capillary motion, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of, or even in opposition to, any external forces like gravity.

Surface tension could be defined as the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of the water molecules.

(b) Surface tension and viscosity are unique properties of liquids that depend on the nature of intermolecular interactions. The stronger the intermolecular interactions, the greater the surface tension. Intermolecular forces play a role in viscosity, because stronger attractions between molecules cause them to resist flow more strongly. Liquids that have strong intermolecular forces tend to have high viscosities. Therefore, Viscosity and surface tension of liquids increase as intermolecular forces become stronger.

(c) As temperature increases, viscosity and surface tension decrease because the raise in temperature speeds up the molecules and the movement makes the liquid move faster so the viscosity decreases.

(d) The kinetic-molecular theory explains why gases are more compressible than either liquids or solids. Gases are compressible because most of the volume of a gas is composed of the large amounts of empty space between the gas particles. At room temperature and standard pressure, the average distance between gas molecules is about ten times the diameter of the molecules themselves. When a gas is compressed, as when the scuba tank is being filled, the gas particles are forced closer together.