What determines a substance's viscosity?

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SUMMARY

The viscosity of a substance is primarily determined by the strength of its intermolecular bonds, with stronger bonds leading to higher viscosity. Temperature plays a crucial role; as temperature increases, viscosity decreases, exemplified by glass, which has a viscosity of approximately 10^35 poise at room temperature but becomes more workable at higher temperatures. Additionally, larger molecules exhibit higher viscosity compared to their smaller counterparts, as seen in the comparison of propanol, ethanol, and methanol.

PREREQUISITES
  • Understanding of intermolecular forces
  • Basic knowledge of thermodynamics
  • Familiarity with molecular structure and size
  • Concepts of quantum mechanics related to physical properties
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  • Research the impact of temperature on viscosity in various substances
  • Explore the relationship between molecular size and viscosity
  • Study intermolecular forces and their effect on physical properties
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Chemists, materials scientists, and students studying fluid dynamics or physical chemistry will benefit from this discussion on viscosity and its determining factors.

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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.
 
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.
 
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...)
 

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