Question

How do intermolecular forces affect viscosity?

Answer 1

Hint: The resistance in flow of a liquid is defined as viscosity. Higher the viscosity, thicker the liquid and higher the resistance to flow. The coefficient of viscosity varies for different liquids.

Complete step by step answer:There are many factors which affect viscosity of a liquid. Intermolecular forces present in a liquid is a factor which affects its viscosity. Higher the intermolecular forces, higher will be the viscosity. When there is a strong intermolecular force, the molecules of the liquids are strongly bonded to each other. This induces a resistance to move. The liquids whose molecules are polar or capable of forming hydrogen bonds are more viscous. The attractive force between the molecules of the same type is called cohesive force. Hence we can say that higher the cohesive forces in a liquid higher is its viscosity. For example, the atoms present in honey are oxygen and hydrogen which can form stronger hydrogen bonds. Hydrogen bonds are very strong intermolecular forces. It holds the molecules together and induces strong cohesive forces. Hence honey is a highly viscous liquid. The other major types of intermolecular forces are dipole-dipole interactions and London dispersion forces.

Additional information-
Another important factor which affects viscosity is the temperature. When the temperature of liquid increases, the kinetic energy of the molecules increases. The molecules move faster and they get enough energy to break the intermolecular force of attraction between the molecules. Hence viscosity of liquid decreases.

Note:
Measuring the viscosity of a liquid is very important in real life. It helps in production and transportation of liquid. The shape of the molecule also affects the viscosity of the liquid.