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Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: scientizscht on 27/12/2019 16:32:49

Title: What is the net rate of mass flow through a semipermeable membrane?
Post by: scientizscht on 27/12/2019 16:32:49
Hello

If we have a deflated semipermeable balloon (so the external pressure is 1Atm) and the osmotic pressure of the permeable molecule is 0.5Atm, will the balloon fill with the molecule or because the external pressure is higher, it will never fill?

Thanks!
Title: Re: What is the net rate of mass flow through a semipermeable membrane?
Post by: evan_au on 27/12/2019 22:05:39
It's not clear from the description if the molecule of interest is inside or outside the balloon? (or both?)
- Is the molecule of interest dissolved in a liquid, or floating in air?
- Is the same solvent present inside and outside the balloon?
- Is the semi-permeable membrane permeable to the solvent molecule, the dissolved molecule, both, (or neither)?

Assuming the same solvent is present inside & outside the balloon, and the molecule of interest is only present on the inside of the balloon, and the membrane is permeable to the solvent and not the solute, then the solvent will move from the outside to the inside, inflating the balloon. The inflation will stop when the tension of the balloon equals the osmotic pressure.

Title: Re: What is the net rate of mass flow through a semipermeable membrane?
Post by: scientizscht on 28/12/2019 14:12:47
The molecule is a gas dissolved inside a liquid, the sack is empty and immersed in the liquid and the membrane is permeable to the molecule only.

What will happen?