Explain the effect of increasing the temperature of a liquid on intermolecular forces operating between its particles. What will happen to the viscosity of a liquid if its temperature is increased?

Increasing the temperature of a liquid affects the intermolecular forces operating between its particles in several ways:

1. Increased Kinetic Energy: As the temperature of a liquid increases, the average kinetic energy of its particles also increases. This increased kinetic energy causes the particles to move faster and collide with each other more frequently.

2. Weakening of Intermolecular Forces: Intermolecular forces, such as van der Waals forces, hydrogen bonding, and dipole-dipole interactions, are responsible for holding the particles of a liquid together. When the temperature of the liquid increases, the increased kinetic energy of the particles overcomes these intermolecular forces more easily. As a result, the intermolecular forces weaken, leading to a decrease in the cohesive forces holding the liquid together.

3. Increased Thermal Motion: Higher temperatures lead to greater thermal motion of the particles within the liquid. This increased thermal motion disrupts the ordered arrangement of particles and reduces the tendency for the particles to remain in close proximity to each other.

4. Expansion of Volume: The increased kinetic energy of the particles at higher temperatures causes the volume of the liquid to expand. This expansion results from the particles moving farther apart from each other as they gain energy, leading to a decrease in the density of the liquid.

Regarding the viscosity of a liquid, increasing the temperature typically leads to a decrease in viscosity. This is because higher temperatures result in weaker intermolecular forces, as discussed above. Weaker intermolecular forces allow the liquid particles to move more freely past each other with less resistance, reducing the internal friction within the liquid and hence its viscosity.

In summary, increasing the temperature of a liquid weakens the intermolecular forces operating between its particles, leading to reduced cohesion and increased thermal motion. As a result, the viscosity of the liquid decreases as its temperature increases.