Diffusion and Osmosis - For Teachers

[@TobyOnTube]

I would like to be tested / criticised on the following comment: in the beginning when demonstrating diffusion I do not think the experimentor demonstrated diffusion. I think she demonstrated brownian motion. And possibly not even that. The hot glas is in a thermal inequilibrium: the glas, the water, the room do not have the same temperature. The surface or top part of the hot water is cooler compared to the bottom part. Therefore it is likely that you have a circular convection current transporting energy from bottom to the top part. However, no circular current is seen. Thus the change in solute concentration is likely due to a combination between brownian and convection motion. A better experimental setup would be to have a heated chamber (can be acquired and biologist use it relatively often in their labequipment). In that setting, everything (water, glas, and room and also the solute substance) is in thermal equilibrium thus ruling out convection. My intuition tells me that transport via convection is much larger than brownian motion. Please comment on all this.

[@sciencenorth]

Hi @TobyOnTube, We appreciate your scientific curiosity! At the beginning of the video, we explained that diffusion is the movement of molecules from a high concentration to a low concentration. The purpose of the demonstration with the food colouring and the water at different temperatures is to show that the food colouring spread out more quickly in the warmer water than it did in the colder water. This was to explain that diffusion happens more quickly in warmer fluids. In the terms you are describing, we oversimplified in using the word diffusion having not considered convection or Brownian motion. Convection does explain the movement of the molecules in the fluid but it wasn’t the focus of the video. There may be other experimental setups that better demonstrate diffusion but again, that wasn’t our goal with the food colouring. The actual demonstration of diffusion was shown with the following two demonstrations to show diffusion through a semipermeable membrane using the dialysis tubing. Thank you for your question. We encourage you to go forth and carry out your own experimental methods to test your hypotheses!

[@francescar8017]

Hehe im a student watching a vid for teachers

[@juibi8006]

savage

[@noahlong3195]

Same 🥱🥱

[@salomek7606]

My teacher told me to watch this

[@Simplydarrell]

Know your role!!! Jk

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[@reaper7884]

Got here from online class, btw who's here in 2020

[@jessicas9315]

me :]

[@kavinelango3888]

@Angel Fires same

[@sumithhebbar]

Ayyyy

[@anumwarsi937]

Same got here from online class

[@XSypherX]

same here

[@technocratenitin9937]

Do you know ...that was awesome .for so many years a was perplexing In osmosis and diffusion .but today it is crystel clear .. Thanks a lot .God bless you..

[@nicebassbro6753]

Crystel

[@ariesdelosreyes9275]

Hello, we are using this as a reference for our online Bio Lab. Thank you!

[@grummy3770]

I’m on a zoom call while watching this for school lol

[@kyuubinoyoko01]

Lymphedema certification brought me here. Thanks for the refresher!

[@princekaonga3373]

As a student teacher at Chalimbana University, I find this video more useful on the related subject; Diffusion and Osmosis

[@plvto1436]

Online school brought me here

[@robloxmain1368]

same mad unlucky

[@harveyjamesadams8987]

plvto oh me too

[@kezzathebesta3176]

welp and here we are as well, online school man.

[@zainabhussain5343]

me 2

[@simir8165]

Me too

[@wilfredapetorgbe8609]

wow really helpful thanks a lot looking forward to your next video

[@ssana2000]

Dr.S.S.Ahmed, from Hyderabad, India I really appreciate your efforts you made for this video..Its awsome. Will you please let me know the preperation on Semi Permeable Membrane too........

[@anisurrahman6633]

Please, show the experiment from a closer camera. Than it will be effective.

[@nancyboakye8129]

I am a student I really love this video the best explanation thanks for sharing this video it has helped me clearly to understand osmosis and diffusion thanks

[@nancyboakye8129]

❤️

[@hilarioalejo2348]

The best explanation, thanks for sharing your knowledge and your comprehension.

[@hannahbermeollanos155]

I understood all your explanation, is the best.

[@abdulhafeez1828]

This is one of the peoductive vedios that i ever seen..keep making and spreading the knowldge

[@itzsafah-um4pf]

Did anyone notice that she added 2 drops of red food colouring into the beaker of hot water and only 1 drop of blue food colouring into the beaker of cold water? And I wanna know if the amount of drops added matters

[@TobyOnTube]

The Best way to go around this is to do diffusion experiments yourself. At least that is my plan. Demonstrating diffusion is not easy. The mean distance of a solute particle (food color) in a solvent (water) increases with the sqrt of time. This is one of the major results in Einstein's 1905 paper. This means that in the beginning things evolve (diffuse) rapidly but then slows down for larger and larger time periods. A complete mixing of the solute in the solvent could take days.

[@xx_Rising_Thunder_xx]

I’m in class and me and my friend started laughing while reading these comments instead of doing our work 😂😂

[@AshKetchum09]

I’m watching this so I can make a flip book animation for science. Best teacher ever.

[@ramadhanmajeedmogga4239]

Thanks I appreciate for your help 🙏

[@noorsaif8346]

So Ur saying that if I fart somewhere where it is hot it will spread places further? OMG this is perfect!

[@SNEHA1999.]

🤗very well explained ☺️

[@yossefrefaey]

Helped me alot with my study thank you

[@sciencenorth]

That is so great to hear, thanks for sharing, Mr. Refaeizz! :)

[@SemaAkca-fl5xh]

awesome, thank you for sharing this video

[@rimamariya177]

Your explanation is really helpful 👍👍

[@simiyusegunoluwaseun1731]

that's a great explanation.keep doing well!!!!. thanks

[@sciencenorth]

Thanks for watching and for letting us know, Simiyu! :)

[@simonforster4776]

A very good explanation - thanks

[@rajatrodney259]

Is the second experiment (Starch and Iodine) an example of diffusion or osmosis?

[@ackylahbyron5356]

I'm a student and this vid helped alot

[@NotSoFunnyAnimator]

Dang, I can't watch this, it says it's for teachers.

[@courageofhumanity2006]

Thank you very much make for such video.

[@Itsyourdailyidk]

This teached better than my science teacher

[@studyland4779]

Is this for a student of class 6th

[@archivaljrvelasco237]

is there a script for this or manual?

[@misterlawlor]

Great video. I particularly enjoyed it in 2x speed.

[@abhinandanmehta915]

Thanks for this vid,helped me a lot..

[@shreenidhi3683]

We enjoyed this video a lot. Thankyou !

[@georgetteemary9420]

Now I understand well thank u

[@RR1R561]

Camera should always be focused on the experiment and not on the experimenter.

[@superdog797]

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.

[@colletteikeanyibe1487]

Is osmosis from a region of high concentration to region of low concentration

[@ArticPup]

Using this video for school, Tysm this helped me a lot and it was easy to understand

[@simir8165]

Thanks for this video,it was very helpful

[@dah-bu1fi]

I love ❤ this video or experiment

[@1.Cs.22]

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[@whatdoyouknow4843]

The video is good. The one comment I will make is that the instructor could talk slower to allow people to follow better.

[@anujarora0]

Keep doing that was a great fun with good knowledge

[@vinayaksharma795]

Good one

[@petergabriel2813]

Hey guys pls what's the set up for this practical

[@akuaamo5973]

How diffusion in liquid and osmosis in water

[@loganmosling3314]

When you are a student watching a video for teachers >:)

[@thomasanderson1416]

Are you Canadian?

[@xtgamesv.2673]

this really helped thank you!

[@KirssisPeguero]

Excellent job!

[@alsaineybarry2598]

So great we are really learning

[@nixmakes]

1:21 that's not diffusion at all, that's convection! Random molecular movement takes weeks on the size of your beaker! I made a video about this: kzbin.info/www/bejne/gn-Thpifm7V2sNk

[@TobyOnTube]

I support this comment. Another useful experiment to perform would be to utilize a heated chamber much like the one used in biology labs to establish thermal equilibrium between glas, water and the environment.

[@lovelylyfe932]

I can't figure out how to calculate diffusion rate

[@carleli7162]

Great explanations!!! Good job!!!

[@jonni2734]

Really interesting!!

[@mingeuncho5877]

정말 잘 했습매다

[@TobyOnTube]

Well, it does not demonstrate diffusion. It demonstrates convection.

[@prassaadbehara4152]

Good Job.

[@thedreamofplanrotherangerg8271]

It can be easily define by this type of example

[@muskanali1236]

I am in 9th class from kashmir and that was my question why osmosis takes place through a semipermeable membra ne and i was thinking like what about diffusion now it's clear that diffusion occurs into a semipermeable membra ne.

[@masumbillah3124]

Excellent

[@Mahdyslh]

As a 12th grade student, thank you

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I like it this video ❤❤

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Tq this helped me in my science exhibition ❤️

[@studying548]

best superb BINOD

[@pateldivy6464]

Great contribution to teachers thanx...👍👍

[@akuaamo5973]

Great

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Thank mam for is demonstration it is use full for my studies

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[@restyseptiayu2658]

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Nice

[@mingeuncho5877]

Very well

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nice experiment ;)

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[@giftofeducation300]

Mind blowing explanation.

[@amrita770]

U said it very well but focus the camera front

[@emmanuellaopokuabrafi4673]

Thank you 😌

[@vasundhara2024]

I am a student....I really loved this video...it explains a lot☺️😊

[@peising4189]

what if you swap the sucrose with glucose solution? Glucose will diffuse out of the tubing while water molecules will just diffuses into the tubing until an equilibrium is reached , and so no change in the level of the solution in tubing and beaker, is that right?

[@patiencendidiamaka622]

I need to have a class of biology everyday,I can I get help

[@patiencendidiamaka622]

I am a student,and I'll love to learn more

[@shanthala1345]

Thanku 🥺🥺

[@لاقوهالابالله-غ5ص]

Thanks you💙

[@studyland4779]

I am in 6th class and my sir said to watch this video🤨

[@moezbali]

The explanation you give for the first experiment is false. The food coloring molecule are dispersed by convection movements. Diffusion only act at a very small scale. For example, it takes a molecule of oxygen 6 hours to travel 1 cm using only diffusion and a month to travel 10 cm!

[@TobyOnTube]

How do you make this calculation? You likely use Einstein's diffusion equation and then consider the molar mass of oxygen and set distance equal 1 or 10cm and calculate the time?

[@stephanieoyebamiji4854]

thank you

[@dearanonixyhylo8656]

So since this is for teachers... and I'm a student... do i become a teacher after watching this video

[@phb1955]

Well, the problem with the first part of the video is that most of the differences in mixing rates are likely the consequence of differences in convection. This is apparent because the changes shown in the video reveal very clearly correlations between regions that are obviously streaming. The only way to do the comparison properly on the effects of temperature on diffusion is to have the 2 beakers in 2 different rooms with ambient temperatures exactly equal to the temperature in the corresponding beaker. This is needed to to eliminate temperature gradients and the resulting convective flow. When one does that you will see a very different result!

[@nixmakes]

You're 100% correct, and the internet is full of these wrong demonstrations. They teach these at schools too!! I made a video about this: kzbin.info/www/bejne/gn-Thpifm7V2sNk By the way, in the last part the show a '24 hours later' clip and that's clearly a lie.. the liquid is even flowing down the tube....

[@dimlighty]

Do you know any video that has the experiment as you've said it should be? I would like to see the result.

[@TobyOnTube]

There is a video about the misconception of diffusion experiments.

[@moezbali]

The relation between diffusion and temperature is hidden in the diffusion equation. It is part of the "diffusion coefficient" D. The explanation is that temperature influences the average speed of the molecules, therefore increasing the frequency of collision between molecules and consequently, increasing the "speed" of diffusion.

[@TobyOnTube]

@@moezbali : hmmm, try and look up fxsolver and "online diffusion time calculator" (to make life easier) and plug in typical values. For the temperature you can consider i) 20 C and ii) 70 C (reasonable estimate as shown in the video). For the distance you can chose say 5 cm as a reasonable distance when looking at the video. If you calculate the time for the food colouring to travel a distance of 5 cm you will find more than 380726120 days. This is much longer than what we see in the video. The experiment in the video does not demonstrate diffusion (a very slow process). Likely the experiment shows turbulent convection due to a an increasing temperature gradient from top to bottom. Would you agree?

[@dr.zahraa.]

عاشت ايدج

[@lorens205]

That is will be my research in University 🔥

[@zmzm107iq]

♥♥

[@janettemartel6502]

I have to do this lab tomorrow and I just want to be prepared and understand how to do it

[@daudakasozi8654]

incradible

[@tebashamll7567]

طالبة سادس 🙏💜

[@malaisamysivakumar6016]

best explanation, thanks