Osmotic Pressure within pressure vessel

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Discussion Overview

The discussion revolves around the behavior of osmotic pressure within a high-pressure vessel filled with an incompressible liquid, separated by a membrane with differing solute concentrations. Participants explore the implications of this setup on fluid flow and pressure dynamics, drawing analogies to biological systems.

Discussion Character

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

Main Points Raised

  • One participant suggests that if the vessel is incompressible and completely filled, there would be no flux due to the inability for volume change, implying that any net flux would create a pressure differential exceeding the osmotic pressure.
  • Another participant counters that osmotic pressure can drive solvent across the membrane, potentially leading to rupture if the membrane cannot withstand the pressure, referencing biological examples of cells in hypotonic solutions.
  • A follow-up question is raised about energy transfer in a turgid system where the rigid membrane prevents flux and pressure change, indicating a need for clarification on how energy is transferred in such scenarios.
  • One participant emphasizes that for no flow to occur, the pressure on the pure side must exceed that on the concentration side by the osmotic pressure, noting that in a compressible fluid scenario, a slight pressure difference could lead to flow, while in an incompressible case, even a small flow could establish pressure balance.

Areas of Agreement / Disagreement

Participants express differing views on the implications of osmotic pressure and the behavior of fluids in this scenario. There is no consensus on whether flux can occur or how energy is transferred in the described system.

Contextual Notes

Participants highlight assumptions regarding incompressibility and the nature of the membrane, as well as the dependence on specific conditions such as pressure differences and fluid properties.

Who May Find This Useful

This discussion may be of interest to those studying fluid dynamics, osmotic processes, or biological systems involving osmotic pressure and membrane interactions.

Tom79Tom
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Hi could someone point me in the right direction about the following scenario
A high pressure vessel is 100% filled with an incompressible liquid
A membrane separates two sides with differing concentrations one (one may be zero) of an impermeable solute.

upload_2014-11-5_17-16-11.png


What would occur ?
My feeling is that there would be no flux as there would not be 'volume' ability for it to occur
Any net fux would create an immediate pressure differential greater than the osmotic pressure. Is this correct.
I don't even think that it matters how strong the membrane is as it would be supported on all sides by the incompressible fluid?
 
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It depends on what the membrane is- there is osmotic pressure driving solvent across the membrane, equivalent to a hydrostatic pressure- so the membrane could rupture. This happens with living cells lacking a rigid cell wall placed in a hypotonic solution: water enters the cell, swelling the cell and bursting the membrane.
 
Thanks for that, going for the Biology analogy we are talking about a turgid system , the rigid membrane disallows the flux and pressure change.
So if the volume cannot increase how does the energy get transferred ?
 
Tom79Tom said:
Thanks for that, going for the Biology analogy we are talking about a turgid system , the rigid membrane disallows the flux and pressure change.
So if the volume cannot increase how does the energy get transferred ?

I don't understand your question- for example, plant cells have a rigid cell wall and can withstand an osmotic pressure jump. What do you mean by 'energy get transferred?'
 
Last edited:
The pressure on the pure side would have to be higher than the pressure on the concentration side by the osmotic pressure in order for no flow to occur. No fluid is completely incompressible, so for a compressible fluid case, if the pressure difference was not just right, some small amount of flow would occur. However, in the limit of incompressibility, any infinitecimal amount of flow would be sufficient to establish the pressure balance.

Chet
 
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