Q12.60P - Chemistry: Molecular Nature Of Matter And Change

Question

Does the strength of the intermolecular forces in a liquid change as the liquid is heated? Explain. Why does liquid viscosity decrease with rising temperature?

Step-by-Step Solution

Answer

The strength of the intermolecular forces decreases as the liquid is heated. This is because of the increase in the kinetic energy of the molecules which compensates for the intermolecular bonding.

The liquid viscosity decreases with the rising temperature because as the molecules gain energy, the intermolecular forces of attraction decrease enormously, thus decreasing the viscosity of the liquid.

 

Step 1: Effect of temperature on the molecular level

As the temperature increases, the energy supplied by the external source is compensated for the increase in kinetic energy. This triggers the motion of the molecules, thus decreasing the strength of the intermolecular interactions.

 

Step 2: Effect on the liquid viscosity

As, the intermolecular interactions decrease, the hold between the molecules due to force of attraction also decreases, which leads to a lowering of the viscosity.