Why the process of diffusion takes place

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    Diffusion Process
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Discussion Overview

The discussion centers on the process of diffusion, specifically why molecules, such as gases, move from regions of higher concentration to lower concentration until equilibrium is reached. The scope includes theoretical explanations and conceptual clarifications related to entropy, molecular movement, and statistical behavior in gases.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants suggest that diffusion is driven by entropy, with a preference for the least-ordered state requiring less energy to maintain.
  • Others argue that a lower concentration represents a more orderly system, leading molecules to prefer moving toward that area due to energy considerations.
  • One participant explains that higher concentrations lead to more frequent collisions, resulting in a statistical tendency for molecules to drift toward lower pressure regions over time.
  • Another perspective introduces Brownian motion, suggesting that individual molecules move unpredictably, and over time, the probability of finding them becomes equal throughout the space, indicating diffusion has occurred.
  • A brief mention of momentum and energy is made, though it lacks elaboration.

Areas of Agreement / Disagreement

Participants present multiple competing views on the mechanisms behind diffusion, with no consensus reached on a singular explanation.

Contextual Notes

The discussion includes various assumptions about molecular behavior, the influence of temperature, and the shape of the reservoir, which remain unresolved.

mubashirmansoor
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Hello,
I wonder why the process of diffusion takes place...
Why should the molecules of gas for example, travel from a region of higher concentration to the region of lower concentration till an equilibrium is achieved?

I'll be thankful for your guidance :)
 
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Basically, it's just entropy in action. Assuming gases of similar density, the least-ordered state is preferred since it requires the least energy expenditure to maintain.
 
Like danger said , a lower concentration of molecules versus a higher concentration of molecules , the lower concentration is the "more orderly system" and less energy would be required to remain in that state. The molecules would prefer to move to that area . The movement itself is due to the constant movement of gas particles.
 
The higher the concentration of molecules, the more likely it is for a given molecule to suffer a collision traveling over a given distance. This means that when a molecule gets knocked toward regions of higher pressure (concentration), it travels, on average a shorter distance before it collides with another particles than when it gets knocked toward a region of lower pressure (We call this concept the mean free-path).

This means that molecules are more likely to drift to regions of low pressure over time. The fact that there is a great many molecules, means that you will get a net drift of molecules from the high pressure region to the low pressure region.

Keep in mind that diffusion is inherently a statistical phenomenon - the vast numbers of particles involved means that the behaviour of the group can be predicted with accuracy despite this.

Claude.
 
Momentum and energy.
 
May i explain this way (not concerning entropy) : Suppose there's a reservoir full of water and a mall drop of ink inside it. For brownian motion, an individual molecule, both water and ink, will move to an unpredictable spot within the reservoir after some time. The probability of finding a given molecule after a long enough period of time is equal everywhere in the reservoir. And thus the diffusion has taken place.
The time to get to equilibrium depends on many things namely: temperature (brownian motion), reservoir shape etc..
 
Thanks from everyone contributing to this thread...
 

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