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Questions tagged [osmosis]

Osmosis the the movement of molecules through a permeable membrane barrier. It occurs as the molecules of a solvent stabilize the concentration of solute particles on either side of the barrier. Osmosis does not require input energy, it does deplete the kinetic energy of the solution.

Osmosis the the movement of molecules through a permeable membrane barrier. It occurs as the molecules of a solvent stabilize the concentration of solute particles on either side of the barrier. Osmosis does not require input energy, it does deplete the kinetic energy of the solution.

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Why does the ideal gas law exactly match the van't Hoff law for osmotic pressure?

The van't Hoff law for osmotic pressure $\Pi$ is $$\Pi V=nRT$$ which looks similar to the ideal gas law $$PV = nRT.$$ Why is this? Also, in biology textbooks, the van't Hoff law is usually instead written as $$\Pi=CRT =\frac{NC_m RT}M$$ where $C_m$…
user257533
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Physical explanation of osmosis

I want to understand the forces involved in osmosis. If I have a molecule of water and one of a salt in the left side of a semi-permeable membrane, and a water molecule at the right side, what forces make the right side molecule travels left and…
Leopoldo Sanczyk
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How is it possible for tall trees to pull water to heights more than 10m?

Which force actually drives water so high up, since pure atmospheric pressure will only get you up to about 10 meters if you're using suction and a long straw and yet tallest trees are over 100 meters ( trees do basically have long continuous…
Kugutsu-o
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By what mechanism is a growing tree root able to lift heavy concrete pavement?

A tree root lying under several square meters of 100mm thick concrete pavement can cause the pavement to lift up as it grows. What forces are involved in creating this lift? I vaguely understand that the growth process is a matter of cell division,…
Igby Largeman
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Acer saccharum (Sugar Maple) Sap & Freezing

This may or may not be the appropriate scientific discipline to ask this question of, but I'll give it a shot. I'll happily invite chemists to chime in as well. It's time to tap sugar maples in the North East USA once again. What we essentially pull…
Tortuga Torben
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Why would tennis balls filled with sulfur hexafluoride explode?

An answer at Chemistry.SE tells the following anecdote: Another fill gas to avoid is sulfur hexafluoride. A tennis ball manufacturer once decided to fill tennis balls with sulfur hexafluoride, assuming this would prevent the balls from going flat…
Ruslan
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Osmotic pressure as a force

Where does osmotic pressure as a force originate? When salt water and fresh water are put together, they would be comfortable to stay as they were if the concentration difference weren't considered, because they seem to be in a mechanical…
user196075
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Does diffusion MRI measure diffusion or osmosis?

I am trying to understand the physical property which is measured in diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI). I read that these methods estimate the apparent diffusion coefficient (in DWI) or the diffusion tensor (in…
srcerer
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Does there exist a membrane that has unbalanced concentration as equilibrium?

In osmosis, there is flow of solvent particles from a region of lower solute concentration to a region of higher solute concentration, until such time that the concentration on each sides are equal. But does there exist a membrane in which the…
non-sensical
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Osmotic pressure "equilibrium"?

Consider a box with two compartments separated by a semipermeable membrane. The first compartment is initially at pressure $P_0$ and contains the solvent ; the second compartment is initially at pressure $P_1$ and contains the solvent and a…
lohey
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Is osmosis stronger or weaker than gravity, and by how much?

Suppose you perpare a jar of salt water and another of sugar water and invert one on top of the other with a divider between them, and then carefully remove that divider so the liquids are in contact. Will the concentrations of salt and sugar reach…
Joshua Frank
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Where is the energy involved in osmosis?

Osmosis creates pressure on the side of the membrane with higher concentration. But where does the energy for this come from?
Volker Siegel
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Where does the energy for osmosis come from?

A thought experiment: A U-shaped tube with semi-permeable membrane at the base. The tube is completely thermally isolated from its surroundings. The liquid (solvent) is at some temperature $T$. When solute is added to one side of the tube the fluid…
Alex
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Is the mechanism behind osmosis attraction of water molecules or pressure differences?

I am trying to get an understanding of the physical mechanics behind osmosis. About half the sources I have found say that it is due to differences in pressure, but some say that it is due to the attraction between water molecules. Is there more…
user180969
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Entropy as a driver behind processes

I sometimes encounter explanations of phenomena where only entropy is quoted as a driver, for example, osmosis, diffusion, hydrophobic effect... But can entropy ever be the sole driver of a process? I encountered 'entropic force', is it a real…
Filip VdB
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