Diffusion, Osmosis and Dialysis (IQOG-CSIC)

Diffusion, Osmosis and Dialysis.
Video of scientific popularization. Animation.
This video has been produced in the Institute of General Organic Chemistry of the CSIC (IQOG-CSIC), Spain, by Guillermo Corrales, as part of its task for promoting Science Communication and may be freely used for educational and science popularization purposes.
Canal Divulgación. Divulgación científica.
Instituto de Química Orgánica General (IQOG-CSIC)
Created by Guillermo Corrales Morales
Músic: Carlos Estella - Happiness Has Harmony II

[balazsdinh]

Had to watch this video as an assignment but definitely did not expect this dramatic music for a video about diffusion

[technicaldixitji]

thanks for directly coming on the point well illustrated

[iiiiiiiii]

I watched this to see if all of his videos have that kind of dramatic music, and yes I enjoyed the music again

[davidschmidt]

EXCELLENT Vid!! Well paced, well illustrated. So many vids interchange the expressions of the SOLUTE moving from high to low compared to the solvent. A lot of my students were easily confused. This one is the best.

[baylee_baby_]

This video was far more helpful than any of the others, thank you <3

[chiconiko]

This explained it way better then my teacher explains it almost all day in class she kept saying it’s the same thing but different and proceeded to say they both are high concentration to low but different this is literally not the same one a full on uncontrolled to controlled but added more water to the concentrated side to dilute the salt particles so it ends up dialysis!

[abdullahabh]

Excellent animation.. This called the real use Animation... Hope for such more

[angelarose]

I'm sorry but I laughed so hard at the music

[githice]

thanks a billion for this illustration, should have added ultra Filtration

[aneesmushtaq]

It was really very good and understandable.

[sharonramola]

Animation super keep continuing all the best

[superdog]

OK I think I figured out a mechanism for osmosis. Sal's explanation is kind of correct but doesn't quite express it right.

The gist of it is that there is a net momentum vector for all the matter in the system that sits on the solute-solvent mixture side of the membrane. If you break the system down into two masses, the mass of water, and the mass of solute, we see that the mass of water's (solvent's) center of momentum movement is directly in the middle of the system over the membrane. However, when we look at the mass of solute's center of momentum, we see that it's in the middle of only the solute-solvent side. When you take the average of these two momentum vectors you get a net momentum vector that has a center somewhere between the two in physical space, so the tendency overall is for the water to move in the direction of the solute-solvent side toward the center of mass of the system.

Another way to think of it is that the barrier imparts energy to the system only on the side in which it is capable of deflecting matter (solute side). The Brownian motion of the molecules is the driving energy of the movement of molecules in the system. Where does the energy come from from the Brownian motion? Well, perhaps there is some internal energy at the subatomic/nuclear level, but I suspect it's more driven by the addition of heat from the environment and the transfer of kinetic energy to the particles from the barrier and walls. If a molecule hits the membrane, it is accelerated in the opposite direction. Energy is imparted to the molecule from the wall, and the wall gains energy from the particle. With each exchange, some kinetic energy is lost due to friction. Because the membrane is, on net, only interacting with the solute particles, any kinetic energy that the solute particles lose to the membrane barrier is lost only in that side of the system, but not the other half. This would imply the overall kinetic energy of the solute-solvent system is less than the pure-solvent side, which would obviously lower the water pressure and thus move water, on net, into the solute-solvent mixture side.

But, you might ask, osmosis is powerful enough, apparently, to work against gravity. This requires work, so energy LOSS doesn't seem to really explain how it can do work. Well, like I said, the Brownian motion of the particles is constant overall, so whatever inputs to the Brownian motion of the particles are, it must be the energy into these inputs that osmotic energy is driven by. It must be the case that the heat of the environment is going into one side of the system at a higher right than the other. I suppose that the solution must have the same temperature throughout on both sides of the membrane (does it? I suppose this could be measured). The order of energy seems to be:

heat from environment --> Brownian motion of liquid particles (Kinetic Energy) --> energy lost to membrane barrier

The energy lost to the barrier must be small compared to the increased input from the environment, otherwise you wouldn't be able to do work like elevate the solution against gravity. I would therefore speculate that the rate of heat intake in the system is greater on the solute-solvent side, because for the Brownian motion to remain constant, one needs an increased amount of energy to compensate for the energy lost at the membrane.

So that's my hypothesis about osmotic mechanism. Any thoughts?

The next question I have is: if this description is correct, does it imply that the total osmotic pressure is linked (proportional to) to the surface area of the membrane, or that the surface area of the membrane merely affects the rate of osmosis overall? Intuition at first tells me that the increased surface area of a membrane should increase the osmotic pressure overall, however as far as I know, the osmotic pressure is directly proportional to the solute concentration only, not the membrane surface area. This may imply that the surface area of the membrane only affects the rate of exchange, but not the overall osmotic pressure. This could be tested empirically by simply having two separate identical systems in terms of water mass, solute concentration on one side, and varying only the surface area of the membrane, and then measuring (1) what the rate of water movement is, and (2) what the overall end result is at equilibrium. If the rate varies but the end result is the same, then the membrane surface area doesn't affect the osmotic pressure. If the end result varies, then the osmotic pressure is proportional to the surface area of the membrane. As a secondary experiment, you could measure the temperature of the fluids and the rate of heat exchange on both sides of the membrane.

[michaelsmaragdakis]

Very nice video, I should point out though that there is an inconsistency that would be useful to clarify. During osmosis water molecules move through the membrane on both directions, but the ones that move towards the higher concentration are more. From our point of view we see water moving to the right but that is the net movement. While it might not be important for the purposes of the video, it should be noted for academic purposes. Same stands apparently with dialysis. Both phenomena stop at some point as the number of molecules moving left and right become equal.

[anandchaurasiya]

Super Animated vedeo it is so easily define

[faraaxguure]

Damn the music was a bit too vibey for me to focus

[prof.marius]

sorry but that was the most epic way to do this

[edgelord]

where was this video in ELEMENTARY ? HUH ?