How does the viscosity of a liquid change as temperature increases?

The viscosity of a liquid typically decreases as the temperature increases. This behavior can be understood through the kinetic theory of liquids. As temperature rises, the thermal energy of the molecules also increases. This increased energy leads to greater molecular motion, allowing the molecules to overcome intermolecular forces that resist flow. As a result, the liquid becomes less viscous, or "thinner," facilitating easier movement among the molecules.

For many common liquids, this trend is consistent, making it a reliable observation in thermodynamics and fluid mechanics. The specific decrease in viscosity with temperature can vary among different liquids, but the general trend holds true across a wide range of cases. Understanding this relationship is essential in various applications, such as process engineering, where the flow characteristics of fluids are crucial for designing efficient systems.