Question

What is Viscosity? Explain how it varies with temperature.

Answer 1

Hint: Viscosity is the measure of degree momentum transport in a fluid perpendicular to the flow of velocity due to flow sheer. The intermolecular forces in liquid and gases are different, when temperature is raised they show change in viscosity.

Complete answer:
Viscosity is a measure of degree momentum transport in a fluid perpendicular to the flow of velocity due to flow shear. According to the kinetic theory of gases, viscosity is proportional to the square root of absolute temperature.
Since In liquid there will be molecular interchange similar to those in gases.
There are additional substantial attractive, cohesive forces between the molecules of a liquid. Here both cohesion and molecular interchange contribute to liquid viscosity.
The impact of increasing temperature of a liquid is to reduce these cohesive forces and increase the rate of molecular interchange. This effect causes decrease in shear stress while the latter causes it to increase. Therefore, liquid shows decreases in viscosity with increasing temperature.
Gases are made up of particles that are very far apart. When the temperature is increased the particles of gas move faster and collide more often, resulting in greater resistance of friction. The more is the friction in gases the more is its viscosity.

Note:
The physical and chemical properties of solids, liquids and gases are all different. The intermolecular forces are different in all of them. In solid the bonds on atoms are very strong and intermolecular forces are strong, in liquid the atoms are loosely bound and have weak intermolecular forces and in gases the atoms are not bound they move freely and thereby very weak intermolecular forces.