Answer to Question #262179 in General Chemistry for MAY

Question

Describe the roles of intermolecular attractive forces in each of these properties/phenomena?

Answer 1

Kindly note;

The phenomena/properties being referred to are omitted/ not specified

The condition of the question is modified to read

"a) Define viscosity, surface tension and capillary action

b) Describe the roles of intermolecular forces in each of these properties/ phenomena"

Solution

Part A

Cohesive forces are intermolecular forces between molecules of the same substance and they are responsible for phenomena such as viscosity and surface tension.

Viscosity is the resistance of a liquid to flow.

The stronger the intermolecular forces between liquid molecules the higher the viscosity of a liquid.

Cohesive forces between like molecules are responsible for liquid viscosity.

Surface tension is the elasticity of the surface layer of a liquid due to the liquid minimizing its surface area.

This property results from the cohesive forces between molecules of a liquid, and it causes the surface of a liquid to behave like a stretched elastic skin.

Adhesive forces are intermolecular forces of attraction between dissimilar molecules

Adhesive forces are responsible for phenomena such as capillary rise.

Capillary action is the flow of liquid within a porous material due to the attraction of the liquid molecules to the surface of the material and to other liquid molecules

The adhesive forces between the liquid and the porous material, combined with the cohesive forces within the liquid may be strong enough to move the liquid upwards against gravity.

Capillary action can also occur when one end of a small diameter tube is immersed in a liquid (Capillary rise).

If the adhesive forces between liquid molecules is stronger than the cohesive forces between liquid molecules, the liquid flow up a narrow tube unassisted against gravity.

The rise stops when the weight of the liquid and the adhesive forces are in balance.