Talk:Osmosis/Archive 2

Archive 1

Archive 2

Introductory sentence

The intro paragraph currently reads:

Osmosis is the movement of water molecules across a semi-permeable membrane from an area of high concentration to an area of low concentration. The movement (diffusion) across the semipermeable membrane does not stop (as is the case with any diffusion) but the net movement reaches zero when equilibrium is reached.

Osmosis is the movement of water molecules across a partially-permeable membrane down a water potential gradient.[1] More specifically...

Has no one noticed that there are two introductory sentences? It's been like that for over two months. The first sentence, which appears to have been added as a simpler explanation, is simply wrong. It was added by an anonymous editor here. Osmosis is not the movement from "high concentration to an area of low concentration" (concentration of what?), but is movement down a potential gradient. Or, in simpler terms, movement from high water potential to low water potential.

I'm removing the first sentence. These kinds of articles, about scientific concepts which are rife with misconceptions, need to be very closely watched. 76.24.222.22 (talk) 11:22, 31 August 2010 (UTC)

The remaining sentence remains a misconception still - as it constrains the general and widely applicable concept of osmosis to only one single medium. That happens when taking definitions from biology textbooks without broader knowledge of the subject. It's high time that someone gets this straight. --Burkhard (talk) 17:14, 31 August 2010 (UTC)

Section of basic explanations

In this section was stated "In a solution, the water is diluted (i.e., the concentration of water is lowered)". I deleted this because concentration of water cannot become lower if we dissolve substance in it, volume of solvatation remains same as volume of pure water, and water molecules dont dissappear if we dissolve some substance in it, that means that the concentration of water remains same. Maybe someone wanted to say that effective concentration of water becomes smaller due to the fact that part of the molecules of water are used for solvatation of molecules of dissolved substance and thats why there is less effective concentration of water. But perhaps would be better to look in some book before we return this to article. --Tekstovi (talk) 13:12, 19 March 2011 (UTC)

Are you saying that water has the same concentration in a solution as it does when it is "pure?" Because that's obviously not true. Take it to the extreme with 99% ethanol and 1% water, or 1% ethanol in 99% water. Solvated compounds occupy volume; solutes increase the entire volume of the solution, thus the average distance, or concentration of water decreases as you add more solutes to water (generally). Statistically it indicates chance of water-impact on the membrane. Although solvation recruitment also factors in there... then you'd move onto discussing entropy/potential/DG's. That section shouldn't have been deleted, it should've been augmented.

And I also changed the thermodynamic and entropy explanation of osmosis because it was confusing. When we talk about entropy, we look entropy of whole system before and after osmosis and compare which one is higher. And not like previouss version talking about entropy in one side of membrane, entropy on another side of membrane, and then somehow entropy "moves" from one part of membrane to another, there were also some unenecary comparations of entropy (by the way entropy of pure water is higher then entropy of water in solution, because there is bigger order of water in solution because of solvatated water plus water which moves chaotically, then just chaotic movement in pure movement, this was also mistake in previouss version. But it is also irelevant because we need to look at entropy of whole system, its very hard to conclude which is the entropy of whole system if we start looking entropy of every component, and its also wrong because it needs to be considered whole system). --Tekstovi (talk) 13:26, 19 March 2011 (UTC)

One problem with the entropy based explanation is that it is necessarily incomplete. Entropy is just one of several forces, which may influence a biphasic system across a semipermeable barrier. Equilibrium is given by the Gibbs–Duhem equation:

${\mbox{d}}G=V\cdot {\mbox{d}}p-S\cdot {\mbox{d}}T+\sum _{i=0}^{N}\mu _{i}\cdot {\mbox{d}}n_{i}=0$

The systems state is driven by pressure and temperatures changes (the latter might be ignored for isothermal systems), and changes in the concentration (to be more precisely - the number of particles) of components having a particular chemical potential. Entropy is a one constituent of the chemical potential. Explaining osmosis solely by changes in entropy would only be valid for systems where all other forces are held at the same level - which is obviously not the case for an osmotic system where you have changes in osmotic pressure. Regards, --Burkhard (talk) 18:15, 19 March 2011 (UTC)

yeah maybe we can add more things about it ... --Tekstovi (talk) 15:12, 23 March 2011 (UTC)

Doubt about definition of osmosis

As I thought osmosis is not difusion of water , but diffusion of any solvent through semi permeable membrane from place of lower concentration to place of higher concentration ? I will check in book tonight to be sure , thought ... --Tekstovi (talk) 16:57, 16 March 2011 (UTC)

Surely not just water but any solvent. Changed. Materialscientist (talk) 00:11, 17 March 2011 (UTC)

Why is this article being ravaged continuously? Osmosis relates only to water, and please do not keep putting in wrong definition over and over again. This wiki is being muddied up with entries from people who know little and want to see their handiwork on Wikiedia. — Preceding unsigned comment added by Hroychow (talk • contribs) 03:59, 4 October 2011 (UTC)

Well, we go not by our beliefs but by reliable sources. For example, Britannica says "Osmosis. the spontaneous passage or diffusion of water or other solvents .." And your references are .. ? Materialscientist (talk) 04:34, 4 October 2011 (UTC)

"cleaning this up"

I think it's pretty important some mistakes, misconceptions and inconsistencies in this article are improved, especially due to it being a science article and therefore probably a more frequently visited article. Refering to osmosis only in the context of water is woefully ignorant. Worse is the fact that whoever last edited the article keeps switching between "solvent" and "water".

Also, why is "basic explainations" needed? Trying to dumb down a subject is not encyclopedic, unless it is fully relevant and necessary I think it should coolly be removed. --Mooticle (talk) 23:23, 11 January 2011 (UTC)

No, it is not "woefully ignorant." The opposite is true, indeed. Osmosis does only involve water.

I'd say know your audience. In this case, a basic explanation is exactly what people are using this content for. If you are concerned with the usage of the term water and solvent interchangeably, then fix it. We could also just use "For example," as a header to water based "examples" of osmosis. In general, the language of this article might need to be improved, but it is at least refreshing to see it discussed from an entropic standpoint, rather than the pervasive (and incorrect) steric one. — Preceding unsigned comment added by Dmitchwk (talk • contribs) 09:40, 5 February 2011 (UTC)

For the subject of osmosis there is noch such basic explanation that could be correct or even complete; the concept of chemical potential (which is much broader than the more special case of water potential used in the introduction) is a prerequisite when discussing equilibrium states (that's what you can expect as result in an osmotic systems). This implies that any qualitative explanation not talking about chemical potential (like entropy) must be inherently misleading, as it leaves out other forces, as pressure, gravity or even temperature gradients (thermoosmosis). Remember: Osmosis is magical phenomenon (to cite Luis Fillipe del Castillo: El Fenómeno mágico de la ósmosis).

Since equilibrium is reached at exactly the point where the chemical potential of the solvent (or gas or whatever is carrying the movement of molecules in a given osmotic system) is equal on both sides of the semipermeable barrier (which does not necessarily need to be a membrane) - there is no qualitative or quantitative correct explanation without this concept. What can be done staying below this level of explanation is describing the phenomenon. That's what I tried in the german counterpart, where the article starts with an observation everyone should be familiar with (cherries bursting when in touch with raindrops) and then moves over to the description of the osmotic pressure before diving deeper into the thermodynamic details of the osmotic potential.

One more word, there are probably hundreds of textbooks defining osmosis. Unfortunately those definitions might be plain wrong, too restricted or are intended to be used in a particular context (e.g. biology, medicine ...). Simply citing such a definition from just one source is not helpful at all. It's easy to find another source defining the subject completely different. Regards, --Burkhard (talk) 13:15, 5 February 2011 (UTC)

Basic explanations still bugs me, but not as much as some of the information in this article that is just plain wrong. Osmosis does not necessarily describe solvent movement between a membrane. Osmosis is not "solute potential" it is "solvent potential", which is reliant on the sum of solute potential and pressure potential. The introductory paragraph also fumbles around with energy definitions. Everyone should be aware that energy cannot be created, saying such a thing in this article is completely unnecessary. Osmosis is a inter-passive process, implying that the random thermodynamic properties of the solvent are associated with kinetic energy, and this will inevitably aim to create a dynamic equilibrium. The work generated by osmosis is equal to the work required to create the solvent potential gradient, honestly the line "Osmosis is a passive process like diffusion" would be less misleading. If we're going to dumb this article down and slowly introduce concepts like entropy then at least be constant with that policy.

either be scientifically correct throughout or state a simple (yet correct) definition and then go into the finer detail. All this ambiguity and waffling makes the article obsolete. Statements like "does not create energy" are wrong, irrelevant, and are derogatory to people who use these articles to gain depth, information and understanding about osmosis. --Mooticle —Preceding undated comment added 10:37, 2 October 2011 (UTC).

Seriously is anyone willing to fix the basic explanation? At least we got rid of the junk about occlusion and steric blocking. But as it reads right now I think it isn't viable. I'm not even sure where to begin in restating the whole thing. I propose that we give a qualitative explanation of the process, and then go into detail with free energy and entropic explanations. If I felt bold enough to edit it right now I'd delete the entire paragraph and begin again. Keeping this in the context of a water based example. i. Explanation of concentration and statistical events (approachable) ii. Explanation of free energy of the system (leading) iii. Processing that free energy. (causality) Thoughts? — Preceding unsigned comment added by Dmitchwk (talk • contribs) 20:50, 30 October 2011 (UTC)

Request for Edit

Please change the internal redlink plasmolyzed to point to plasmolysis in the article. (Little things bug me.) --Flashgamer001 (talk) 00:55, 23 January 2013 (UTC)

Ah, never mind. It just confirmed me. --Flashgamer001 (talk) 01:03, 23 January 2013 (UTC)

Osmosis permeability

The use of permeable and semipermeable in the Osmosis article do not comply with the definitions of those words in Wiktionary. In particular, the two references to "partially permeable" make no sense, and the diagram for showing a "semi-permeable membrane" applies instead to a permeable membrane. In addition, the word semipermeable is not hypthenated. — Preceding unsigned comment added by 67.61.148.8 (talk) 16:52, 23 March 2013 (UTC)

Osmosis permeability

The use of permeable and semipermeable in the Osmosis article do not comply with the definitions of those words in Wiktionary. In particular, the two references to "partially permeable" make no sense, and the diagram for showing a "semi-permeable membrane" applies instead to a permeable membrane. In addition, the word semipermeable is not hyphenated. — Preceding unsigned comment added by Jeffrey A Glassman (talk • contribs) 16:59, 23 March 2013 (UTC)

Lead image

One frame of a computer simulation of osmosis

The meaning of the image in the lead section is not apparent. Either the caption should be expanded to better spell out the meaning of it, or the image should be replaced with something more evocative of osmosis. Any suggestions? --TSchwenn (talk) 00:47, 22 May 2012 (UTC)

Agreed! Perhaps a simple schematic drawing would be better? 16:16, 30 March 2013 (UTC) — Preceding unsigned comment added by 24.130.83.74 (talk)

TERRIBLE ARTICLE - FACTUALLY FALSE

THIS ARTICLE IS GARBAGE. From phys.org (Read more at: http://phys.org/news/2013-04-osmosis-wrong.html#jCp )

"A misconception is that osmosis always happens down a concentration gradient. When you dissolve something in water, the water doesn't necessarily get more diluted. Depending on the substance, it can get more concentrated."

"[a] misconception is that osmosis is limited to liquids... it works just fine for gases, too."

"Another misconception [is] that osmosis requires an attractive force. It doesn't."

"Another misconception is that you don't need to invoke a force to explain why the water flows... It's thought that, like diffusion, it's a spontaneous process...But, in fact, there is a force. It's complicated how it happens, but it turns out that the membrane ... exerts a force." The thermodynamic theory for osmosis was firmly established 60 years ago. This article echos incorrect explanations that, as recent articles have shown (see link), persist in the chemical and biological communities. I note that this article is locked, no doubt due to fan-boys who are unable to understand they are just plain wrong. Do what you want. The article is wrong. It is a disservice to the Wikipedia universe.173.189.76.217 (talk) 01:35, 2 April 2013 (UTC)

Well, one problem is that the rather abstract concept of chemical potential is required to describe osmotic processes correctly - unfortunately not the most intuitive concept - thus most textbooks try to avoid it. Solute concentration is only a factor as far as it influences the chemical potential of the solvent (or precisely - the passing component). With respect to the notion of the membrane exerting a force - this is as wrong or correct as every wall exerts a force on particles trapped in a container.

I agree that the english article is pretty much incorrect. In particular the "basic explanation" is absolutely misleading. The best approach would be IMHO:

• describe experimental findings independant of "physical" interpretation as a first step
• only then osmosis should be discussed in the context of equilibrium thermodynamics, in particular the Gibbs-Duhem equation
• then derive the Morse-Frazier and van't Hoff equation for osmotic pressure
• only then possible "phyisical" interpretations of the microscopical processes may be discussed - believe it or not - even nowadays science has not arrived at a common understanding of which physical interpretation is the right one, see e.g. Borg's essay (for a citation see the article)

BTW: The article is locked for IP-Editors as it was and still is quite often subject to plain vandalism. If you like to contribute, please get a user login and your edits certainly will be welcomed. I am currently working on the german sister article de:Osmose and have plans to restructure it according to the ideas outlined above, see e.g. de:Benutzer:Drahkrub/Osmose/Grundlagen. Regards, --19:35, 2 April 2013 (UTC) (from de-WP.) — Preceding unsigned comment added by Drahkrub (talk • contribs)

From someone who doesn't know much about this, while I can understand that diffusion might be insufficient to explain all of the osmosis effect, I don't see why it can't be at least part of the explanation... Tmfs10 (talk) 03:47, 3 August 2013 (UTC)

What particularly do you have in mind? --Burkhard (talk) 18:00, 7 August 2013 (UTC)

Proposal: Physical/thermodynamically correct explanation

Osmosis is the flow of components in a system partitioned by a semipermeable layer or membrane that prevents some components from passing the membrane freely. A passing component will spontaneously move across the membrane to the side where its chemical potential µ_p is lower.

If the passing component is a solvent like water, its chemical potential µ_w will be lowered in the presence of dissolved solutes; increasing the concentration of a nonpassing solute on one side therefore directly affects the osmotic gradient. Onset of volumetric inflow of the passing component will increase the overall volume, lowering solute concentration and increasing hydrostatic pressure at the same time - both factors will decrease the chemical potential µ_w on this side. Thermodynamic equilibrium will be reached when the value of µ_w becomes equal on both side. As solute concentration and hydrostatic pressure both contribute to chemical potential µ_w, osmotic flow in a closed system generally will not restore equal solute concentrations. Increasing pressure on one side can decrease the chemical potential sufficiently enough to reverse the direction of spontaneous osmotic flow (Reverse osmosis).

Baseline: Osmosis tends to equalize the chemical potential of the passing component (usually a solvent). Difference in solute concentration (non passing components) is only one of several factors that determine the osmotic gradient of a given system.

--Burkhard (talk) 21:03, 4 April 2013 (UTC)

I like this suggestion. I strongly think the bit about osmosis being a type of diffusion should be removed. This claim is untenable given numerous experimental results. For example, it is well known that water will move to a higher concentration in some cases. (Some solutes will increase the concentration of water, not dilute it.) These data are shown in the Handbook of Physics and Chemistry. Apparently physicists have had osmosis figured out for over 60 years, but (sadly, for me as a biologist) biologists still have not. It is easy to find inaccurate references in the biology literature, so I am sure some people will not want to let go of the incorrect claim that osmosis is diffusion, or, for that matter, that osmosis relies on attractive forces of solutes for water. I suppose one solution would be to report that biology has conceptions of osmosis that do not comport with the conception of osmosis held by modern physics, and cite sources for this divide.108.213.79.33 (talk) 05:01, 2 April 2014 (UTC)Michaplot (talk) 05:04, 2 April 2014 (UTC)

Semi-protected edit request on 14 March 2015

The basic explanations section needs to split up at "Osmotic pressure is the main cause of support in many plants. The osmotic entry of water raises the turgor pressure exerted against the cell wall, until it equals the osmotic pressure, creating a steady state."

This is a new topic and should be in a new section.

104.156.228.85 (talk) 21:16, 14 March 2015 (UTC)

Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format. — {{U|Technical 13}} (e • t • c) 02:31, 15 March 2015 (UTC)

Expansion of this article

This article needs to be expanded and cleaned. Check out the german article, it gives a indication of how the article should be written and reformatted.

193.156.161.92 (talk) 06:31, 7 May 2014 (UTC)

Some time ago I carried out a simple calculation in which I assumed an analogy between solute ions in seawater and particles in a gas, then I used the ideal gas equation, pV=NRT, to calculate the pressure that those ions would exert within the solvent. The number I got was almost identical to the measured osmotic pressure of seawater versus fresh water. In the model that I used osmosis occurs because the solute exerts its pressure against the free surface of the solution and that surface will move if and only if fresh solvent can enter the solution without solute ions leaving it. The semipermeable barrier meets that criterion, so we have a simple, straightforward, and easy-to-understand explanation of osmosis. I would rewrite the Wikipedia article myself to reflect this model but for the fact that it would constitute an act of original research. However, I am confident that somewhere some physical chemist has carried out the same or similar calculations of osmotic pressure and published them in a professional journal. All we need is someone sufficiently familiar with the literature of physical chemistry (and that excludes me) to find that article and use it as a reference in rewrite the explanation of osmosis on Wikipedia. Good luck, folks!Kanawishi (talk) 16:33, 2 August 2014 (UTC)

The so called "solute bombardment theory" - the idea that osmotic pressure is caused by solute molecules hitting the membrane (not the free surface) - was described first by Jacobus_Henricus_van_'t_Hoff in his 1887 classic paper "The role of osmotic pressure in the analogy between solutions and gases", http://urila.tripod.com/Hoff.pdf. It has been falsified around the 1950s though, see e.g. Francis P. Chinard, Theodore Enns: Osmotic pressure. In: Science. 124, 1956, S. 472–474. For a more recent review on this topic see e.g. F. Kiil: Kinetic model of osmosis through semipermeable and solute-permeable membranes. 2002. doi:10.1046/j.1365-201X.2003.01062.x. and Frank G. Borg: What is Osmosis. arXiv.org, e-Print 2003: http://arxiv.org/abs/physics/0305011v1.

So your simple, straightforward, and easy-to-understand explanation of osmosis is neither correct nor original research. Thanks anyway. --Burkhard (talk) 19:49, 8 April 2015 (UTC)

Semi-protected edit request on 24 September 2016

typo in section Mechanism, paragraph 6, last sentence: One fact to take not of is that --> One fact to take *note* of is that

81.242.211.232 (talk) 12:19, 24 September 2016 (UTC)

Done Topher385 (talk) 12:33, 24 September 2016 (UTC)

Article Cleanup

This article is still in need of major cleanup and thus I have flagged it for such. A complete re-write would likely be best course of action.

• Explanations need to be more concise, scientific and include fundamental underlying principles, especially the section on the mechanism. Thus it should probably be written by someone knowledgeable in chemistry or physics with more literature references (ie textbooks and articles).
• Information is poorly organized/in wrong sections or even better suited to other articles. There should probably be a section on application of osmosis and how it relates to other fields such as biology.
• Quality of writing and sources are not up to Wikipedia standards.
• Many complaints in talk page still don't appear to have been resolved.

Devon (talk) 07:59, 6 October 2016 (UTC)

Explaining Article from American Journal of Physics

What about the Explanations in this article, that the membrane exerts a repulsive force on the solution which is the driving force behind osmosis?

I found it here: https://www.researchgate.net/file.PostFileLoader.html?id=56ee07d5cbd5c226ac0d9b92&assetKey=AS%3A341536895193098%401458440149864 — Preceding unsigned comment added by 37.201.243.48 (talk) 20:08, 12 March 2017 (UTC)

Semi-protected edit request on 1 October, 2018

In the "Mechanics" section, change Template:More citations needed to Template:Refimprove section, since the latter fits this situation better. 94.234.44.113 (talk) 14:14, 1 October 2018 (UTC)

Your energy and mine would be better spent actually finding sources for this section, but since the requested edit does no harm,  Done —KuyaBriBri^Talk 15:17, 1 October 2018 (UTC)

A Commons file used on this page has been nominated for deletion

The following Wikimedia Commons file used on this page has been nominated for deletion:

• Osmotic Gradients.png

Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 11:36, 10 October 2018 (UTC)

Basic explanation

The references refuting the basic explanation in this article are some random guy's lab for his students, and a news article. I could find a hundred texts indicating that osmosis is a colligative property related to entropy and diffusion. We seem to be ignoring that here in light of exceptions. Does someone have real evidence that diffusion, potential, and entropic concerns are not the primary driving force? Because as it stands this article is at odds with every published explanation and model I've seen in my career. — Preceding unsigned comment added by 168.156.43.141 (talk) 16:00, 24 February 2015 (UTC)

I have always been confused about osmosis and this article did little to correct my confusion. As I was studying it, most of the verbage used was not "plain language" , or at least did not reach me. Studying the picture at the top of the article I think I finally gained some understanding in spite of the caption rather than because of it. Better captioning would have helped me. I would suggest that the caption be modified to include an example. As in " the left beaker in the example has a liquid, such as water that had a dissolved solid, such as salt. it is of low concentration, as say 7 parts per million, with each blue dot representing that 1 millionth fraction. The right side has a example concentration of 27 PPM. due to the lower concentration on the left side. water passes the semi-permeable membrane over to the right side to try to equalize the right side of the breaker at the same 7 ppm concentration, as is shown in the beaker on the right side."

The net spontaneous flow of solvent particles from low concentration to high concentration through semi permeable membrane is known as osmosis. It is due to difference in vapour pressure of solution and solvent. Amankushwaha0412 (talk) 17:24, 1 February 2019 (UTC)

Update of an external link

Hi, I would like to announce an update of the link to the "NetLogo Osmosis simulation for educational use"

URL: https://koj.kftg.ch/Java/Osmosis_fast.html

Best regards, Johannes Kottonau — Preceding unsigned comment added by Johummel (talk • contribs) 13:24, 26 August 2019 (UTC)

This article is horrendous and the explanation is wrong

Osmosis is not unrelated to solute-solvent attractions, in fact, that is the exact reason for osmotic pressure as easily demonstrated by virial theorem in this article.

https://arxiv.org/ftp/physics/papers/0305/0305011.pdf

Solvent molecules actually are more tightly bound than when there is no solute present. If that was not the case then solvation wouldn't occur and most things that are soluble wouldn't be soluble. Reason why a lot of things are soluble without external input is because the energy that is liberated from binding water molecules to the solute is bigger than the energy necessary to break apart the solute-solute interactions and solvent-solvent interactions to make space for the solute molecules to come through.

Ultimate proof of that is that mixtures of solvent and non-soluble solute do not create an osmotic pressure.

Osmosis is not a 100% colligative property. It's an approximately colligative property. Strength of interactions does matter and it can be accounted for via 2nd order terms in virial expansion. Or you could say that osmosis is colligative property in ideal solutions (where any excess hydrophility is neglected but there obviously has to be some hydrophility for actual solution to be possible) — Preceding unsigned comment added by 93.143.60.23 (talk) 10:34, 23 August 2020 (UTC)

From what I understand (though I'm not an expert on this, I've only briefly studied it), osmotic pressure is universally colligative in the dilute limit, for some fairly fundamental entropic reasons. The PDF you linked even states this (which seems to contradict your point?): "An important point is that osmosis is a colligative property". You're also seeing this in your virial expansion, where you have to go beyond the dilute limit (beyond first-order effects) to see the interaction strength mattering.

That said, my understanding is that most discussions of osmosis focus on case of *non-volatile* or low-volatility solutes. Clearly, if a substance can exist in some concentration in a solvent, yet it doesn't volatilize with equal concentration into the headspace above the solvent, then it must have an interaction with the solvent that 'pulls in' the solute particles as they try to escape. So the entire discussion of osmosis with non-volatile solutes does indeed tend to assume *a priori* that some interaction exists.

Why does volatility matter? With a volatile solute, even though the osmotic pressure formula remains colligative, we have to now also consider the solute vapor pressure (also colligative but with a different concentration) which acts against the osmotic push. For a non-electrolyte, the ratio of these colligative pressures will equal the dimensionless Henry solubility. Thus, in the hypothetical case of a ghostly solute that has zero interaction with solvent (and thus is perfectly volatile), we don't get preposterous results.

As for going beyond the dilute limit ... anything can happen, and it really becomes crucial to consider the exact interactions and correlations to properly get the second virial term, as in the Kirkwood–Buff solution theory and such.

So regarding the article, I think it's important to emphasize which statements assume the dilute case, and which statements assume a non-volatile solute. The closely-related article on Boiling-point elevation seems to do a good job of this. --Nanite (talk) 01:45, 24 January 2021 (UTC)

Semi-protected edit request on 22 June 2021

Please add a link to the following terms:

• "net movement or [[diffusion]]"
• "region of high [[water potential]]"
• "can be made to do [[Work (physics)|work]]"

157.157.113.104 (talk) 08:36, 22 June 2021 (UTC)

 Done ScottishFinnishRadish (talk) 11:04, 22 June 2021 (UTC)

Untitled

OK essentially what is happening is this

The side with the larger particles have much more mass, at temperature cube law etc means they are acting as a pump, trillion of small pumps that keep pushing water in every direction, only one of those directions is back towards the membrane, thats where the energy comes from to make the GZ raise of the water.

Think it through you have a picture of a perpetual motion machine, you can let the water from the high part flow back down to the low side and drive a turbine.

Where then is the energy coming from, Heat, surrounding the whole system or particles bouncing around the whole system — Preceding unsigned comment added by JUBALCAIN (talk • contribs) 10:12, 21 May 2021 (UTC)

Mechanism of osmosis not explained

The article does not explain the mechanism of osmosis, it merely says two common explanations are wrong and implies that better explanations (one having something to do with chemical potential, one having something to do with virial theory) exist. This is not helpful, especially to nonexperts such as myself turning to Wikipedia to deepen their understanding. If the mechanism of osmosis is not well understood, it would be helpful for the article to say so directly. If it is well understood, it would be helpful for the lengthy “Mechanism” section to explain it. If it is extremely complicated, it would be helpful for the article to explain it in a high level way with links to related concepts. — Preceding unsigned comment added by 2603:7000:B63F:6020:8C83:6F4C:CE36:FFC (talk) 06:52, 28 February 2021 (UTC)

I agree. In https://doi.org/10.1119/1.4722325 paper, authors refute many mechanisms and offer their own "The Brownian motion of the solute molecules bring them into occasional contact with this field, at which time they receive some momentum directed away from the membrane.

Viscous interactions between solute and solvent then rapidly distribute this momentum to the solvent molecules in the neighborhood of the membrane. In this way, the membrane exerts a repulsive force on the solution as a whole. Since additional pure solvent can freely cross our idealized membrane, it flows into the solution compartment, gradually increasing the hydrostatic pressure in the solution. Thus, a

pressure gradient builds up across the thickness of the membrane. This pressure gradient exerts a second force on the solution,

capable of counteracting the membrane force." However, I myself am not convinced in validity of this mechanism. 128.62.62.10 (talk) 21:50, 29 March 2022 (UTC)

100% agree - I came here to say exactly this! Like you, I am not an expert in this, so I can't add a correct explanation of the mechanism. But as a step in the right direction I am going to take everything that is not about the mechanism out of the 'Mechanism' section and put it in other sections. Hopefully others will be able to come along and clarify the mechanism.

Famedog (talk) 11:21, 25 June 2021 (UTC)

Hello, do you feel the article is now in a better place, with clear direction and simplified explanation? IrishOsita (talk) 19:45, 8 June 2022 (UTC)

Semi-protected edit request on 17 June 2022

change

• NetLogo Osmosis simulation for educational use

to

• NetLogo Osmosis simulation for educational use Johummel (talk) 16:24, 17 June 2022 (UTC)

 Done ScottishFinnishRadish (talk) 19:22, 17 June 2022 (UTC)