https://en.wikipedia.org/wiki/Temperature_dependence_of_viscosity

Dr John Francis Muller thank you for your contribution to the discussion

Yes, the viscosity of a liquid decreases with increasing temperature.

Dr Astra Mundukovna Makasheva thank you for your contribution to the discussion

When a liquid is heated, the kinetic energy of its molecules increases and the intermolecular attraction becomes weaker. Hence, the viscosity of a liquid decreases with increase in its temperature. Viscosity of a liquid decreases with an increase in its temperature. Viscosity decreases on increasing the temperature of liquid because cohesive force among the water molecules decreases. Gas viscosity increases with temperature, whereas liquid viscosity decreases with temperature. Because intermolecular forces weaken with temperature, viscosity decreases. The viscosity of liquids decreases rapidly with an increase in temperature, and the viscosity of gases increases with an increase in temperature. Thus, upon heating, liquids flow more easily, whereas gases flow more sluggishly. The viscosity index (VI) is an arbitrary, unit-less measure of a fluid's change in viscosity relative to temperature change. It is mostly used to characterize the viscosity-temperature behavior of lubricating oils. The lower the VI, the more the viscosity is affected by changes in temperature. Gas viscosity increases with temperature, whereas liquid viscosity decreases with temperature. Because intermolecular forces weaken with temperature, viscosity decreases. Temperature increases typically cause an increase in molecular interchange because molecules move faster at higher temperatures. Viscosity of gases increases with increase in temperature because the velocity of gas molecules increases with temperature hence collision of molecules increases which deceases the ability of the molecules as a whole to engage in the coordinated move.Viscosity generally decreases as the temperature increases. Viscosity generally increases as the temperature decreases. The viscosity of a liquid is related to the ease with which the molecules can move with respect to one another.

The viscosity of a liquid decreases with increasing temperature. This is because the increased temperature causes the liquid molecules to move faster and collide less frequently, which reduces the friction between them.

The viscosity of a gas increases with increasing temperature. This is because the increased temperature causes the gas molecules to move faster and collide more frequently, which increases the friction between them.

The reason for the opposite trends in liquids and gases is due to the different forces that are responsible for viscosity in each state. In liquids, viscosity is caused by the cohesive forces between the molecules. These forces are stronger at lower temperatures, so the liquid flows more slowly. In gases, viscosity is caused by the momentum transfer between molecules. This transfer is more efficient at higher temperatures, so the gas flows more slowly.

Here are some examples of how the viscosity of liquids and gases changes with temperature:

• The viscosity of water decreases from 1.85 × 10^-3 Pa·s at 20°C to 0.89 × 10^-3 Pa·s at 100°C.
• The viscosity of air increases from 1.8 × 10^-5 Pa·s at 20°C to 2.0 × 10^-5 Pa·s at 100°C.

The viscosity of a fluid is an important property that affects its flow behavior. It is used in many engineering applications, such as designing pipelines, pumps, and valves.

Dr Murtadha Shukur thank you for your contribution to the discussion

I agree with Murtadha Shukur that viscosity of liquids decreases with increase in temperature. For gases, viscosity is due to collision between gas molecules. With increase in temperature, gas molecules attain more kinetic energy and the rate of collision is more. Hence, viscosity of gases increases with increase in temperature. This momentum transfer can be thought of as a frictional force between layers of flow. Gas viscosity increases with temperature, whereas liquid viscosity decreases with temperature. Because intermolecular forces weaken with temperature, viscosity decreases. Viscosity generally decreases as the temperature increases. Viscosity generally increases as the temperature decreases. The viscosity of a liquid is related to the ease with which the molecules can move with respect to one another. Viscosity generally decreases as the temperature increases. Viscosity generally increases as the temperature decreases. The viscosity of a liquid is related to the ease with which the molecules can move with respect to one another. When the liquid is heated the viscosity of liquid decreases. As temperature increases, there is an increase in molecular interchange as the molecules speed increases with rising in temperature. At high temperature, molecules posses’ high kinetic energy and thus it can overcome the intermolecular forces to flow faster. Gas viscosity increases with temperature, whereas liquid viscosity decreases with temperature. Because intermolecular forces weaken with temperature, viscosity decreases. Temperature increases typically cause an increase in molecular interchange because molecules move faster at higher temperatures.When temperature increases, the energy level of liquid molecules increases (kinetic energy increases) and the distance between the molecule increases. It causes a decrease in inter-molecular attraction between them, which reduces viscosity. Increasing temperature results in a decrease in viscosity because a larger temperature means particles have greater thermal energy and are more easily able to overcome the attractive forces binding them together.