Viscosity of a liquid ________ by increasing temperature?

Q: Viscosity of a liquid ________ by increasing temperature?

Decreases - Viscosity is the measure of a fluid’s internal resistance to flow. In liquids, it arises due to intermolecular forces that resist the relative motion between adjacent layers. Stronger intermolecular interactions result in higher viscosity, while weaker interactions allow easier flow. When the temperature of a liquid increases, its molecules gain kinetic energy and move more rapidly. This increase in thermal motion reduces the cohesive forces between molecules. As a result, the layers of liquid slide past each other more easily, leading to a decrease in viscosity. This temperature-viscosity relationship is especially noticeable in liquids like oils and glycerin. At room temperature, motor oil is thick and flows slowly. When heated, it becomes thinner and flows more easily. This is why engines require proper temperature regulation to ensure efficient lubrication. The decrease in viscosity with temperature is a general behavior for most liquids, although the rate of decrease may vary depending on the nature of the liquid. For example, polar liquids with strong hydrogen bonding (like water or alcohol) show a noticeable change in viscosity with temperature changes. On the molecular level, as thermal energy increases, the intermolecular attractions (such as van der Waals forces or hydrogen bonding) become less effective in holding the molecules together. This reduces internal friction, allowing the liquid to flow more freely. Unlike gases, which typically show an increase in viscosity with temperature due to more frequent molecular collisions, liquids behave oppositely. This contrast is a key concept in physical chemistry and fluid dynamics. Understanding how viscosity changes with temperature is essential in industries like lubrication, food processing, pharmaceuticals, and chemical manufacturing, where fluid flow is critical to process efficiency and product consistency.

Question

Accepted Answer

Decreases - Viscosity is the measure of a fluid&rsquo;s internal resistance to flow. In liquids, it arises due to intermolecular forces that resist the relative motion between adjacent layers. Stronger intermolecular interactions result in higher viscosity, while weaker interactions allow easier flow.
When the temperature of a liquid increases, its molecules gain kinetic energy and move more rapidly. This increase in thermal motion reduces the cohesive forces between molecules. As a result, the layers of liquid slide past each other more easily, leading to a decrease in viscosity.
This temperature-viscosity relationship is especially noticeable in liquids like oils and glycerin. At room temperature, motor oil is thick and flows slowly. When heated, it becomes thinner and flows more easily. This is why engines require proper temperature regulation to ensure efficient lubrication.
The decrease in viscosity with temperature is a general behavior for most liquids, although the rate of decrease may vary depending on the nature of the liquid. For example, polar liquids with strong hydrogen bonding (like water or alcohol) show a noticeable change in viscosity with temperature changes.
On the molecular level, as thermal energy increases, the intermolecular attractions (such as van der Waals forces or hydrogen bonding) become less effective in holding the molecules together. This reduces internal friction, allowing the liquid to flow more freely.
Unlike gases, which typically show an increase in viscosity with temperature due to more frequent molecular collisions, liquids behave oppositely. This contrast is a key concept in physical chemistry and fluid dynamics.
Understanding how viscosity changes with temperature is essential in industries like lubrication, food processing, pharmaceuticals, and chemical manufacturing, where fluid flow is critical to process efficiency and product consistency.

MCQ Detailed View