What determines a substance's viscosity?

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In summary, a substance's viscosity is determined by its physical parameters, including temperature, pressure, state, and the strength of its intermolecular bonds. Generally, larger molecules have higher viscosity than smaller molecules, and as temperature increases, viscosity decreases. This relationship can be seen in the example of glass, which has a lower viscosity when heated and a high viscosity at room temperature. Ultimately, the concept of viscosity is related to quantum mechanics, although the exact relationship is not remembered.
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The P-manator
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What determines a substance's viscosity? Is it a molecular pattern or something of the sort?
 
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It's related several physical parameters, and thus, ultimately to some quantum mechanics concepts, I don't remember the exact one's off the top of my head.
 
  • #3
In general, as temperature increases for a given substance, viscosity decreases. A great example is glass. At high temperatures when it is workable, glass has a relatively low viscocity but at room temperature it's viscosity is huge (something around the area of 10^35 poise IIRC).

Larger molecules usually have higher viscosity's than analogous smaller molecules. For example, propanol's viscocity is greater than ethanol's which is greater than methanol's.
 
  • #4
Generally, the strength of a substance's intermolecular bonds determines its viscosity.
The stronger these bonds are, the more viscuous your substance will likely be.

(Other factors include temperature, pressure, state, etc...)
 

What is viscosity?

Viscosity is a measure of a fluid's resistance to flow. It is a property that describes how thick or sticky a substance is.

How is viscosity measured?

Viscosity is typically measured using a viscometer, which is a device that measures the time it takes for a fluid to flow through a specific tube or channel. The longer it takes, the higher the viscosity.

What factors determine a substance's viscosity?

There are several factors that can influence a substance's viscosity, including temperature, pressure, and molecular size and shape. Generally, the higher the temperature and pressure, the lower the viscosity will be. Larger and more complex molecules tend to have higher viscosities.

Why is viscosity an important property to study?

Viscosity plays a crucial role in many scientific fields, including chemistry, physics, and engineering. It can affect the flow of liquids in pipes, the performance of lubricants, and even the movement of blood in our bodies. Understanding viscosity can also help us develop new materials and improve industrial processes.

How does viscosity differ from density?

While both viscosity and density are properties that describe a substance's physical properties, they are not the same thing. Density is a measure of how much matter is packed into a given volume, while viscosity is a measure of a fluid's resistance to flow. A substance can have a high density but a low viscosity, or vice versa.

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