What effect do intermolecular forces have on viscosity?

Intermolecular forces play a crucial role in determining the viscosity of a substance. Viscosity is a measure of a fluid's resistance to flow, and it is significantly influenced by the strength of the intermolecular attractions between the molecules in that fluid.

When intermolecular forces are strong, such as in the case of hydrogen bonding or dipole-dipole interactions, the molecules are more tightly held together. This increased attraction leads to greater resistance to movement among the molecules, which in turn results in higher viscosity. For example, honey has a higher viscosity than water due to its stronger intermolecular forces.

Conversely, in substances with weaker intermolecular forces, the molecules are more free to move past one another, leading to lower viscosity. Oils, which often have weaker intermolecular forces compared to water, typically flow more readily.

Therefore, the correct understanding is that increased intermolecular forces correlate with an increase in viscosity, making it vital to recognize the importance of these forces in the behavior of fluids.