Talk:Molecular diffusion

message: It is to specialistic for the general reader looking up diffusion.145.116.1.3 (talk) 07:45, 5 June 2008 (UTC)
thread_title: Mathematics

message: Diffusion is the movement from a high to low concentration along the concentration gradient.
In ternary solutions particles can be tranported from low to high concentrations. Joao
This can happen in binary alloys, too Olof
: Agreed. Molecular diffusion occurs in solids as well as liquids and gases; even pure, unalloyed metals exhibit molecular diffusion. 99.133.144.210 (talk) 01:56, 29 July 2011 (UTC)
thread_title: General discussion

message: I hate it when one page is used for two topics.  Something needs to be done! Either create a page for Diffusion (physics) and Diffusion (anthropology) or kill the anthropology on the diffusion page.
Osmosis= diffusion of water not general diffusion surely. Equally my GCSE biology teacher could have been lying to me...
:I agree the osmosis reference should be removed, and I did so. Danrs 18:45, 15 August 2007 (UTC)
thread_title: Disambiguation

message: I just made a major change to the layout of the page. Since there were alot different types (and sub-types) of diffusion listed inthe article, I grouped them all in one section and moved the relevant information to separate pages on the particular types of diffusion. Hope that made the page a bit clearer than before. Cheers Karol 18:01, 15 September 2005 (UTC)
thread_title:  Types of diffusion in separate pages 

message: I think diffusion is not connected to turbulence, the example of smoke dissipating into the air is a bad example since it involves convection. I have removed the parts accordingly. Lirnup 20:28, 28 September 2005 (UTC)
replies: text: Good work catching that. Also, diffusion isn't quite the same thing as Brownian motion, no? Karol 06:06, 29 September 2005 (UTC)
replies: text:  As I understand it, in the case of diffusion the particles move one by one by brownian motion, but I'm not really an expert on that. Lirnup 06:21, 29 September 2005 (UTC)
replies: text: Sure, in the case of the diffusion of particles, but that is only one type of diffusion since not only particles diffuse. There is also the subtle difference that BM is a description of the stochastic motion of single particles in itself, whereas diffusion is more a dsecription of a process, in which there is a net transport and flux of the diffusing quantity (related to some kind of gradient). Karol 14:37, 29 September 2005 (UTC)
replies: text:  Yes, the brownian motion thing came in only to make a kind of juxtaposition. We better take this out there Lirnup 10:28, 4 October 2005 (UTC)

text: To some extent there is a false dichotomy between convection and diffusion, insofar as "shear induced dispersion" is a coherent concept used to quantify effective diffusivities, see e.g. Taylor dispersion. The key is to establish the scale (in time and space) of the motion of interest- turbulent mixing is an effective diffusion on scales much larger than the scale of the turbulent eddies; for the typically encountered situations the fractal nature of turbulence means that no scale can be found on which it only adds to an effective diffusion, but some media have upper cutoff lengthscales for the turbulent motion. That smoke example was bad and should stay deleted, but convection and diffusion are not always mutually exclusive, and frequently what is called convection on a small scale leads to diffusion on a large scale. 99.133.144.210 (talk) 02:13, 29 July 2011 (UTC)
thread_title:  Diffusion and Turbulence 

message: At 11h04 today (31 october 2005), I added a link to collective diffusion in this article. At 11h06, or 2 minutes later, this link was deleted by user:Karol Langner, on the basis that I should first create the collective diffusion article (I created this article "only" at 11h17). So Karol, a question: are you going to delete all the red links that have existed for more than 2 minutes in this encyclopedia, or should I conclude that you are specifically after my edits? ThorinMuglindir 12:32, 31 October 2005 (UTC)
replies: text: Talk:Degrees of freedom (physics and chemistry) ThorinMuglindir 14:27, 31 October 2005 (UTC)
replies: text: I wasn't even aware that it was your edit, and deleted the red link, because it didn't add anything to that list. And I didn't look at the time, so I also didn't get that the page would be created soon. In any case, I'm not stalking you. Sorry. My bad. Karol 15:01, 31 October 2005 (UTC)
replies: text:  OK no problem. Your edits you do appear sound to me btw. We'd better get across as clearly as possible that diffusion is a very general phenomenon.ThorinMuglindir 16:21, 31 October 2005 (UTC)
thread_title:  A redlink story 

message: I find this page only gives the physical view. There is also the mathematical term of a diffusion (process). Of course these concepts are related, but it's not the same. LARS 18:58, 19 November 2005 (UTC)
replies: text: The mathematical term--and the other uses of diffusion--are in analogy to the mathematical models for the physical process, no?  You can discuss the diffusion equation or a random walk without reference to the physical process, but then there are already articles on those topics.  I added a statement about the analogies in the intro. Danrs 18:53, 15 August 2007 (UTC)
thread_title:  Diffusion (mathematics) 

message: Somebody might want to remove the giant animated GIF from this page. Just sayin'.
*What's your screen resolution? You might want to increase it... — 0918BRIAN • 2006-04-3 07:37
** It's distracting and irritating, and the size contributes to this.  My screen resolution is higher than average, yet I still find the image too big; I have a higher resolution because I want a greater density of information.  It really doesn't take a 12x12 square of pixels to represent a particle.  The image should be reduced to half size, and possibly slowed down (most of the animation shows random motion - the reader currently needs to watch the loop several times to catch the three seconds or so of diffusion). --Will 152.78.191.84 12:16, 14 June 2006 (UTC)
thread_title:  Giant animation 

message: Isn't it because warmer systems have more energy and higher energy molecules move fast? too bad i don't have a reference for that Tsinoyboi 16:16, 21 September 2006 (UTC)
thread_title:  Why does diffusion happen faster in warmer systems? 

message: The example of the sugar cube in WATER is wrong, unless we could guarantee that water is completely still. Otherwise there will be some transport due to convection, and it is also likely that the "sugar water" neat the sugar cube will sink to the bottom of the glass due to its higher density and the gravitational force.—The preceding unsigned comment was added by 201.231.152.118 (talk • contribs) .
:I have removed the examples listed as not being examples of diffusion, because the statement implies that they do not really contribute to the article. Perhaps they could be reworded so they can be included in the article. For instance, I would still think diffusion plays an important role (in addition to convection). Perheps this could be reworded to reflect the role of diffusion?--GregRM 21:57, 19 July 2006 (UTC)
thread_title: Examples of diffusion

message: The following are NOT examples of diffusion:
*A gas distributes itself over a room by diffusion
*A sugar cube in a glass of water that is not stirred will dissolve slowly and the sugar molecules will distribute over the water by diffusion
*Ink in a beaker of water is an example of diffusion. In the end, the ink particles spread evenly throughout the mass of water
According to my textbook, Chemistry & Chemical Reactivity, 6th edition, Thomson Brooks/Cole , cover seen here http://www.newtexts.com/newtexts/book.cfm?book_id=3038, those count as diffusion that ultimately they become scattered. It says so on page It's supposed to be closed containers so they can be closed systems, it's just that those systems are open to other sources of energy to affect the rate system. Rate doesn't mean it's not diffusion. Warmer molecules will just mix faster. Being open systems, heat may be introduced like windows or people in a room, or escape like water evaporating from a beaker. The listed items are still molecules diffusion.
However, in a quiescent medium, gas could distribute evenly across across a room, and the dissolving of sugar will distribute sugar within the water, and the ink particles distributing is diffusion again.  I think the word NOT should have been simply removed.  Wiki editors,  I am new to this, but removing content that is worthwhile to the general public, and relevant, I think you should correct the inaccuracies, and not just remove content.  I know about my little section of the world, but so do other people, even if it is the other way around.Biotechscientist (talk) 02:47, 19 November 2010 (UTC)
thread_title: Removed section

message: Theses have nothing to do with diffusion, they are examples of active transport, require energy and specialized transporters/engulfing machinery:
* Active transport, pumping material across a cell membrane
* Pinocytosis, "cell drinking" intake of small droplets of lipids
* Phagocytosis, carrier proteins are used to transport glucose
Besides Pinocytosis is an intake of small droplets of liquid not lipids, phagocytosis has nothing to do with transporting glucose, it's engulfing of solid particles by cell membranes, read their articles for more info.Enemyunknown (talk) 13:24, 12 December 2008 (UTC)
thread_title: Removed examples

message: Diffusion and Thermodynamics are definitely related but can you say that diffusion occurs as a result of the second law of thermodynamics? isn't it more that The second law of thermodynamics works because of diffusion of heat? Tsinoyboi 16:15, 21 September 2006 (UTC)
thread_title: Diffusion and Thermodynamics

message: The example animation on the page shows a clear example of convection and bulk flow; the higher-density dye sinks in the glass of liquid (with turbulent fluid flow); barely any of the visible mixing is due to diffusion.  After all, diffusion constants for small molecules tend to be a few hundred microns squared per second, meaning that it would take millions of seconds (weeks) for diffusion to equilibrate the dye concentration in the glass.
Does anyone want to keep that graphic as an example of "mixing that isn't diffusion"?  Otherwise, even though it looks cool, I'll just delete it.
Ichoran 04:29, 15 October 2006 (UTC)
replies: text: I agree with the point that convection is not diffusion and doesn't belong here.  A quibble about the use of "Fickian": usually it's used to contrast with other (non-Fickian) forms of diffusion, for example in complex systems, or where the flux depends on the magnitude of the concentration (in addition to the concentration gradient).  It's a little odd to use Fickian to contrast with convection, which is not diffusion at all.  Also, see Fick's law section below.  Danrs 19:04, 15 August 2007 (UTC)
thread_title: Example Animation is Convection not Diffusion

message: The introduction implied that Fick's law and Fourier's law were alternate names of the diffusion equation.  Fick's law is used to derive the diffusion equation, but is not identical to it.  Also, I think the important aspect of Fick's law is not that it labels the diffusing substance as mass (as opposed heat), which was implied, but that the net transport is proportional to the concentration gradient.  There are other possibilities for purely diffusive systems!  I tried to clarify this in the introduction. Danrs 20:04, 15 August 2007 (UTC)
thread_title: Fick's law

message: Is it possible for us to add a section into the article where this process is explained simply? I'm staring at the screen and cringing when I read this - maybe I just have unnaturally low intelligence. The Last Melon 01:53, 26 June 2007 (UTC)
replies: text: Unfortunately, the introductory paragraph was edited to say that diffusion *is* the movement of particles, rather than that this is an *example*.  I'm restoring the more general (i.e. more accurate) text.  If there is a compelling reason to do otherwise, please mention the reasoning here!  128.177.16.8 19:10, 3 October 2007 (UTC)
thread_title:  A section for the shmucks 

message: Thermal diffusion ≠ Heat flow.
Currently Thermal diffusion redirects here, and then this article sends it off to "Heat flow", which redirects to Heat transfer).
This is not the best understanding of Thermal diffusion as in the OED or most places.
— DIV (128.250.204.118 06:03, 21 September 2007 (UTC)
thread_title:  [[Thermal diffusion]] ≠ Heat flow 

message: The diffusion experiment with ammonia and cotton wool seems a little suspect to me.  Won't the rapid evaporation of ammonia increase the local pressure and thus cause slight bulk flow within the tube?  Wouldn't stabbing gelatin with a needle with ink be a better experiment?  The key to doing a good experiment that demonstrates diffusion is to choose a system where non-diffusive flow is greatly retarded by viscosity or somesuch. Ichoran 19:55, 3 October 2007 (UTC)
thread_title:  Diffusion experiments 

message: The term diffusion is derived from the Latin verb husionere which means "to break" but can also mean "leave way"
There is no such word "husionere" in Latin. In fact, I can only assume this is vandalism, since it doesn't bear even a passing resemblance to reality.
http://www.m-w.com/
diffuse
: Etymology: Middle English, from Latin diffusus, past participle of diffundere to spread out, from dis- + fundere to pour
dis-
: Etymology: Middle English dis-, des-, from Anglo-French & Latin; Anglo-French des-, dis-, from Latin dis-, literally, apart;
http://archives.nd.edu/latgramm.htm
diffusilis -e [capable of spreading , elastic]
fusus (1) -a -um partic. from fundo; q.v.
fundo (1) fundere fudi fusum: of liquids [to pour , pour out]; of metals, [to melt, cast]. Transf., [to pour out, shower, give abundantly]; [to squander]; 'se fundere', [to rush, stream]; of sounds, [to utter]; with emphasis on distribution, [to spread, extend, scatter]; milit., [to rout, defeat, scatter, put to flight]. Hence partic. fusus -a -um, [spread out, extended]; 'crines', [flowing free]; of speech, [diffuse]; adv. fuse, [widely, copiously].
Proving once again that an encyclopedia predicated on popular consensus... sucks.
--75.63.48.18 (talk) 08:02, 8 January 2008 (UTC)
replies: text: A quick google search shows that husionere has now successfully diffused around on the net. These usages may now be used as a citation to refute your proposed etymology. 178.38.117.134 (talk) 13:13, 13 April 2014 (UTC)
thread_title:  This etymology is complete nonsense. 

message: I proposed to move this article to Molecular diffusion.
Reason: to better define the scope of the article. "Diffusion" is a large and complex topic.
* For "diffusion in general", there is already an article Diffusion (disambiguation).
* For specific types of diffusion, there are already multiple English Wikipedia articles, as listed on the above disambiguation page. If any specific diffusion-related topic is missing, a new article can be added.
The obviously central yet missing article is that on the molecular diffusion of mass. 
Under the current title, the basic definitions are disputed.  The article does not appear to develop into a useful one, despite an overall large  number of edits.
Cheers. Stan J. Klimas (talk) 21:32, 22 October 2008 (UTC)
replies: text: Complete Tohd8BohaithuGh1 (talk) 19:22, 23 October 2008 (UTC)
thread_title:  Proposed move to Molecular diffusion 

message: The article gives a few examples for typical diffusion speeds such as "In gas: 100 mm per minute". Diffusion is inherently something that is described by the square of length per time unit and these examples (which suggest that 100 mm per 60 seconds equals about 1.5 mm per second) are misleading. Han-Kwang (t) 09:14, 2 February 2009 (UTC)
replies: text: Yes, this is much clearer. Yet, perhaps the examples should be even more clarified or removed altogether because they can confuse. Not sure. Stan J. Klimas (talk) 23:03, 2 February 2009 (UTC)
thread_title:  Example diffusion speeds 

message: The See also section is now rather long with 13 entries. Would it be better to shorten this and rely on the Diffusion Category to aid further navigation? --Art Carlson (talk) 11:35, 9 March 2009 (UTC)
thread_title:  See also section 

message: I just suggested that the page Diffusion equilibrium be merged into this one.  There is only a small amount of material on that page, and this article already has a section on non-equlibrium systems, so it seems like it would fit here. Shanata (talk) 21:29, 20 October 2009 (UTC)
thread_title: Suggested merge of diffusion equilibrium into this article

message: There is also molecular diffusion in solids. This is the origin of aging processes in many solid materials. I would therefore suggest to remove the "(liquid or gas)" in the first sentence "Molecular diffusion, often simply called diffusion, is the thermal motion of all (liquid or gas) particles at temperatures above absolute zero."  — Preceding unsigned comment added by 128.176.210.208 (talk) 17:14, 10 September 2019 (UTC)
thread_title:  Molecular diffusion in solids 

message: Hey authors,
I only had a quick view on this article and I find that already the introductory sentence "Molecular diffusion, often simply called diffusion, is the thermal motion of all (liquid or gas) particles at temperatures above absolute zero." misses some precision. To my knowledge and according to the definition in many basic textbooks in physics, diffusion is the mixing process resulting from random motion, not the random motion itself. The random motion of the fluid particles is rather termed thermal motion.
It seems I cannot edit the introductory section. Please help!
Thanks (Pelicanelson (talk) 10:53, 10 September 2020 (UTC)
thread_title:  Introductory sentence