What is the relationship between viscosity and temperature of liquid and gas?

Answer 1

As the temperature of the liquid fluid increases its viscosity decreases. In the liquids the cohesive forces between the molecules predominates the molecular momentum transfer between the molecules, mainly because the molecules are closely packed (it is this reason that liquids have lesser volume than gases.

The viscosity of the gases increases as thetemperature of the gas increases. The reason behind this is again the movement of the molecules and the forces between them. In the gases the cohesive forces between the molecules is lesser, while molecular momentum transfer is high. As the temperature of the gas is increased the molecular momentum transfer rate increases further which increases the viscosity of the gas.

Answer 2

Actually an increase of temperature of a gas WILL reduce viscocity and a increasing temperature on a liquid will increase viscocity. ~ A 12 yr, old girl :)

This is false. An increase in temperature of a liquid will decrease the viscosity of a liquid, while increasing the temperature of a gas will increase its viscosity. Next time, please don't answer unless you have graduated high school.

Answer 3

The effect of temperature on viscosity of a liquid, according to particle model, as temp. increases viscosity decreases. The effect of temperature o viscosity of a gas, according to particle model, as temp. increases viscosity increases.

Answer 4

Short Answer:

In gasses, forces between atoms are not important and the transfer of momentum (hence force, hence viscosity) between different adjacent regions of a fluid is dues to the movement of particles over long distance. Higher temperature means faster movement means higher viscosity in a gas.

In liquids, forces between particles dominate and shear force is transmitted through those interactions with adjacent particles. Higher temperature means more short distance particle movement and more varied interaction with neighboring particles thus decreasing the effectiveness of transmitting shear force and decreasing viscosity.

Long Answer:

Generally, the viscosity of a liquid decreases as temperature increases.

On the other hand, the viscosity of a dilute gas tends to increase with increasing temperature.

(These are not universally true statements since fluids can be made up of complex substances with peculiar behaviors and such peculiar circumstances require individual explanations.)

This can be understood in terms of shear stress occurring during fluid flow and the explanation is limited to simple non-turbulent flow.

When one part of a fluid is flowing relative to another part, some shear force is transmitted between adjacent regions and that is the essence of viscosity.

In a gas, particles move large distances before collisions and those distance are large compared to the average distance between particles and much much larger than the size of the particle. Thus, when one region of a gas is moving relative to an adjacent region there is interchange of particles between the regions before a collision occurs. In this way, with many particles moving, the region which has one average velocity (vector velocity, not speed) inserts particles in the nearby region which has particles of a different average velocity and the reverse happens as well. Since the particles carry momentum, that momentum is transferred to the new region. The more momentum transferred, the greater the force. (Change in momentum is always accompanied by force.) For a gas, the particles at high temperature move faster, so this process occurs faster. More rapid transfer of momentum between adjacent regions of a gas means more shear force and more shear force is identified as greater viscosity.

In a liquid, the spacing between particles is small. Particles typically move distances that are smaller than the size of the particle before a collision occurs. In fact, because the particles are so close together they exert significant forces on each other and are never truly free of force. It is not really even appropriate to use the term collision because that implies a period of uninterrupted travel and then a sudden change associated with a collision. In liquids, particles are inconstant interaction with multiple neighboring particles, so there is no uninterrupted travel.

In liquids, viscosity is large, hundred or thousands of times larger that a gas, because the forces between particles is important and the size and shape of particles is important. Forces and structure vary greatly between different molecules, so a single explanation will not be able to address the important features of all liquids, but here are some factors that enter.

In liquids composed of longer molecules, there is some entanglement an shear stress is transmitted through the interactions between adjacent particles. These stress soon relax as the particles are rapidly moving and, in a sense, get out of each others way. (In a solid, shear stress is maintained because the relative positions of adjacent particles is maintained.) This relaxation of shear stress due to particle motion is faster if the particles move faster and so viscosity is lower for higher temperatures.

Another way of discussing this is to consider the attractive forces between particles. When shear stress is applied in a liquid, this tends to move particles away from adjacent particles, something that is not favored by attractive forces. The particles will move however and find other attractive forces with other particles. The higher sped of molecules at higher temperature means they change interactions with neighboring molecules quickly, so higher temperature reduces viscosity.

All liquids exhibit some degree of both of the above processes and so not single characterization is adequate.

Finally it should be noted that this is a qualitative explanation and there can be other ways of saying this. Furthermore, viscosity is a microscopic qualitative phenomena involving many particles at once and qualitative explanations can never accurately portray what goes on as well as microscopic theory.
because the viscosity has density so when increase temperature

Answer 5

The higher the temperature the lower the viscosity.

Answer 6

For liquids; Viscosity tends to fall as temperature increases.

For gas; Viscosity increases as temperature increases.

Answer 7

cold temperature makes the gas reduce to possibly liquid

hot temperature makes it still gas since gas is like 100 degrees Celsius(212 fahrenheit)

Answer 8

Increasing the temperature, viscosity is decreasing.