ChemistryPhysics

4 Types Of Viscosity In Chemistry

All liquid substances are susceptible to measurement of their thickness, which is technically recognized as viscosity.

This physical condition depends on a large number of factors, the main one being temperature. For example, honey has a viscosity that varies when it is hot.

Definition:

” Viscosity is a fluid’s resistance to flow, determining its thickness or stickiness. It’s measured in units like poise (P) or Pascal-seconds (Pa┬Ěs)”.

What is Viscosity?

It is the physical state of all types of fluids, which is colloquially represented by the concept of thickness. It arises thanks to the collision of specific masses of the fluid, when they have different speeds and resistance to movement occurs.

The degree of viscosity depends on how much resistance there is, since the higher the level of resistance, the more viscous the fluid will be. Hence, the less viscous ones can move much faster than those with a high degree of thickness.

There are also cases in which there is no type of viscosity. This phenomenon is known as zero viscosity, superfluid or ideal fluid, since in a closed circle they could flow without friction. Generally this occurs only when the liquid solution is in a cryogenic state (at a very low temperature).

Viscosity can be measured through the use of a viscometer, viscometer or rheometer, instruments that reflect the exact force with which a fluid develops its displacement, agreeing that those with a higher level of viscosity have a much slower displacement.

Viscosity can also be measured through gravity, as is the case with lubricating oils, honey and other types of thick substances.

Viscosity definition chemistry:

Viscosity in chemistry refers to a liquid’s resistance to flow, affected by factors like temperature and molecular interactions. It quantifies how easily molecules move past each other, influencing properties such as fluidity and diffusion rates.

4 Viscosity types:

Within scientific studies of the fluid system, four types are recognized:

1. Apparent viscosity

It is identified with the acronym VA. The apparent viscosity depends on the fluid-velocity gradient, that is, it is different depending on the points at which it is located within space.

It is given by dividing the shear stress between the velocity and the deformation of the fluid. In that sense, it acquires a non-linear behavior.

2. Extensional viscosity

This is the type of viscosity in which the fluid is not Newtonian in nature when a tensile stress is applied, while at the same time having a close relationship between the stress and the speed at which the axis deforms, whether biaxial or axial.

3. Kinematic viscosity

It is represented with a V, but the international measurement system allows it to be measured in square meters over seconds. It is obtained at the moment in which the density of some fluid is divided by the dynamic viscosity, both being measured with the same temperature and expressed in the same consistent units.

4. Dynamic viscosity

It is measured through the international system as units of pascal-seconds. It is recognized as the absolute viscosity, since it occurs due to the relationship between the shear stress and the fluid velocity gradient.

Dynamic viscosity can indicate a type of specific resistance of fluids when certain shears (shearing stresses) are subjected after the movement of the particles is exerted.

This type of viscosity is what underlies the theory of temperature, which explains that while there is a higher temperature inside the fluid, there will be a lower level of viscosity.

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