Capillary action and why we see a meniscus | Chemistry

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Capillary action and why we see a meniscus | Chemistry | Khan Academy

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9 жыл бұрын

How capillary action and the meniscus are related to intermolecular forces in water.
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Chemistry on Khan Academy: Did you know that everything is made out of chemicals? Chemistry is the study of matter: its composition, properties, and reactivity. This material roughly covers a first-year high school or college course, and a good understanding of algebra is helpful.
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Пікірлер: 94

@reneelemieuxsmith8003 9 жыл бұрын

This dude must be brilliant. He teaches all the lessons on the website.

@awesomeroger99 4 жыл бұрын

true thing

@jermainegarrick6114 2 жыл бұрын

Yes true thing

@wasikbillah9902 7 жыл бұрын

God bless this man. I understood it crystal clear. Many many thanks.

@GueVonez 9 жыл бұрын

Leave it to chemistry to change completely the way i look at a paper towel

@siddarth1346 5 жыл бұрын

@iroxursox1234567 WHAT?!

@emmap7431 5 жыл бұрын

Lamp look it up sis

@shouri5111 8 жыл бұрын

Very understandable. you must be some kind of hero c:

@davarman3615 8 жыл бұрын

+Shouri No, Sal Khan is just some dude who says things.

@aashayzanpure4248 7 жыл бұрын

Davarman he's a MIT graduate and Harvard post graduate...need to say anything more?

@sincerelysilvia 7 жыл бұрын

He's a mit grad and harvard post grad. He also created a world wide free site for people who are less fortunate, so they can learn mandatory kindergarden to high school curriculums.

@alexandrumoise1511 6 жыл бұрын

But just adhesion doesn't explain capillary action. If it were the case, then the height that the water could rise to would be independent of the tube's length. But that would mean a perpetual fountain if the tube was short enough, which is not what we see. It also has to do with air pressure being lower inside the tube because of the small space that impedes high velocity air particles. Inside the tube there's a gradient of pressure, with a minimum in the middle of it, and normal air pressure at the ends.

@termivan 5 жыл бұрын

sorry for comenting on an old coment but can you please give some sort of sorce because i tried finding what you tallked about, but couldnt find anything. thank you

@rockstarali99 5 жыл бұрын

Ivan Miholić its actually pretty much logic, you don’t need a source for it. But what the OP didn’t point is that due to capillary action, there is a force extered either upward or downward. And THIS force is balanced out by the PRESSURE exerted on or by the OTHER OPEN END. This is why equilibrium is achieved even though there are two open ends on which atmospheric pressure is acting. Because its the liquid weight that balances out the capillary rise/fall, not the atmospheric pressure. Hope it clears something up for ya.

@alvekvale2431 4 жыл бұрын

If the capillary action in any given system is strong enough for a liquid to defy gravity, then that liquid will not suddenly start to adhere to gravity once it reaches the end of the glass tube. The glass tube keeps it from progressing any further once it's reached the end, and the water is not about to spill over (adhering to gravity), because if the water is capable of spilling over at that point, then it wouldn't have been capable of climbing to that point in the first place.

@maverick4900 8 ай бұрын

Thank you for the additional information! I feel stupid that I did not think about this on my own.

@kaniasalsabila2681 6 жыл бұрын

I immediately subscribed without hesitation. this dude explains so well without using convoluted language. this is actually helping me

@pankajsinghbisht4369 6 жыл бұрын

Amazing , one thing I love about this lecture is that he illustrate everything with the help of basic concepts.

@TheWolverine7 3 жыл бұрын

went to take a poop and put some tp in the water so it wouldn't splash. was interested by how the water climbed the tp as I was placing it, so I decided to once and for all look up how capillary action works. ended up being one of the most informative poops I've ever taken thanks to this video 👍

@nancybautista1797 5 жыл бұрын

I’m taking Fluids Mechanics this semester and I really need to understand this forces. Thank you so much Saul!!!!!

@arunmoses2197 2 жыл бұрын

*Sal

@drswish629 6 жыл бұрын

Woah! You are a bloody good teacher

@IndieDX 3 жыл бұрын

Clearly explained! Thank you!

@acidithiobacillusferrooxid3687 4 жыл бұрын

you just saved a random guy's surface chem final, thank you

@2011Sankalp 8 жыл бұрын

damn good video, never thought this is why water sticks to most surface

@varunpandey9341 3 жыл бұрын

good explanation thanks

@aldreivohnaquino3590 3 жыл бұрын

Thanks Sal!

@TheRedstoneTaco 7 жыл бұрын

This fire mixtape on capillary action is better than that other fire mixtape about balancing chemical equations. dont ever take me seriously

@dishayanmandal 5 жыл бұрын

This is really impressive Thank you so much Sir

@mrigankusaharia1741 3 жыл бұрын

You made realize how stupid my university professors are. Never in my life I have learned so much. Thank you. You are my idol.

@DavidAusman 6 жыл бұрын

That so cool. I never realized it is the positive polarity of the glass that attracts the negative polarity of the water to it.

@ihsanulhaq5646 2 жыл бұрын

Thanks sir

@MrWhiteav6 7 жыл бұрын

I love this channel! Thanks for the free info! I find this so cool

@hananahmed1765 3 жыл бұрын

Thank u sir

@mddelman 6 ай бұрын

Very informative video, thanks. Do you have time to answer a question for me? I have a small vessel filled with water. A thin tube (1.5mm inner diameter) hangs an arbitrary distance below the surface and the top is attached to a valve that allows me to release ink into the water. When the valve is open, ink flows freely. When I close the valve, a vacuum is created at the top of the tube, so the flow of ink stops. However, through what I assume is capillary action, water from the vessel is pulled into the tube, apparently displacing ink, which then leaks into the vessel. This continues until all of the ink in the tube has leaked out. My question is, is there any way to prevent this leakage from happening? I cannot change the viscosity of either the ink or the water. The tube could be modified if that would help, but not to the extent of using a much larger diameter tube. I hope you find this question interesting and I'd be most appreciative if you can answer it. Thanks very much!

@Mohamed.U3 5 жыл бұрын

dude thanks so much this helped me alot to understand my last lecture :)

@AnthonyFrancisJones 4 жыл бұрын

Excellent - well explained!

@shreevignesh1564 5 жыл бұрын

Khancave

@payelpandit7467 3 жыл бұрын

Brilliant

@MA-yz7ef 2 жыл бұрын

Does this explain the mess caused when liquid sticks to the outer walls, let's say for a cup when it is poured into another container?

@arabindakumarpal3063 6 жыл бұрын

Thank u verrrry much Sir

@hizbaarshad6524 4 жыл бұрын

what is the height in case of pressure difference on the both sides of meniscus?

@umaveerendra767 6 жыл бұрын

mr khan is the king of the world

@ankushbhawal4428 4 жыл бұрын

Thanks a lot sir

@jayeshahirrao3118 6 жыл бұрын

I have 1 question; as capillarity is due to adhesion then while calculating capillary rise, why we take surface tension in free body diagram instead of adhesive force

@upalikarunasiri9994 2 жыл бұрын

At the equilibrium, the already adhesived water molecules at the top pull the ones on the surface next to those tangentially with force per unit length equals to T of water/air. Hence mg=2 pi r T cos (theta).

@MrJayPuff 7 жыл бұрын

Very good video!

@ABond008ABond008 9 жыл бұрын

I have 2 questions? One what draws water to paper towel and 2 why doesn't capillary action happen on the other side of the of the tube (The outer area).

@shouri5111 8 жыл бұрын

I know the awnswer to your second question. For capillary action to work, the tube has to be very narrow, or else there's no place to 'bump up'.

@ashasalelkar7457 6 жыл бұрын

Answering ur first q..... In simple terms, water really likes to wet certain surfaces (e.g. your paper towel fibers), and is willing to do so against a small amount of gravity. If you have lots of wettable surface area per volume of water, then the water can be pulled up quite a distance.. basically adhesion is occuring here when it happens water will tend to spread over the surfaces of the other material, even climbing against gravity to do so. Cohesion among the water molecules will drag along those water molecules not in direct contact with the material, and surface tension will hold the water together as it adheres to the surface. Adhesion may be strong enough to raise the water against gravity.

@mahwishtahir5617 4 жыл бұрын

I like it

@KumarHemjeet 5 жыл бұрын

how come he can teach all the subjects ?

@jermainegarrick6114 2 жыл бұрын

Yes it form shape

@morancium 6 жыл бұрын

Awesome

@chissstardestroyer 2 жыл бұрын

Isn't water basically magnetic (a water molecule seems to be a very tiny magnet to me), because of the positive and negative charges involved, pray tell, Sir?

@julian.ch_ Жыл бұрын

Does capillary action occur inside the capillaries in our body?

@winduslel2040 4 жыл бұрын

capillary /kəˈpɪləri/ but i still love this vid definitely

@nickbooomerr8150 5 жыл бұрын

capillar reaction helps us to clean the table #usefull : )) (i hope you know what i mean)

@batmanlovesjokerr 5 жыл бұрын

I don't understand the case of mercury why is there a depression in case of mercury. Plz explain me🙏🙏🙏

@mayurakshisingh5922 6 жыл бұрын

hey the paper towel is also showing the capillary action does it mean that paper also has polarity in it????

@jatindersharma9801 6 жыл бұрын

I have one question then why does distilled water doesn't have enough adhesion instead it forms flat meniscus

@chandramaulichakraborty6787 6 жыл бұрын

What happens in the case of mercury and glass then why it is convex form upward?

@theparadigm8149 3 жыл бұрын

What is your question?

@HARSHVARDHAN-im2hb 6 жыл бұрын

Aweaome

@wtfvids3472 4 жыл бұрын

5:54 I see it in a plastic tube. Maybe not so pronounced but it's there.

@sroydetroy6404 2 жыл бұрын

why does the oxygen on water has a positive charge? shouldn't be negative?

@ignodepaula7685 5 жыл бұрын

Watching Corey Taylor teach fluid mechanics is just amazing.

@kikiliu9879 9 жыл бұрын

Hi♡💕💕

@davarman3615 8 жыл бұрын

+Nikki Liu Hello

@kikiliu9879 8 жыл бұрын

+Davarman I don't even remember putting that comment

@davarman3615 8 жыл бұрын

+Nikki Liu I don't blame you, it was almost a year ago.

@kikiliu9879 8 жыл бұрын

+Davarman oh, that's probably why

@haroldwestrich3312 5 жыл бұрын

So if I had a tube made of something that Mercury "Adheres to" stronger than it does itself; would it have a concave meniscus? and be sucked up the tube (a tiny bit because it's heavy)? I think yes, so that means capillary action relies on not only the size of the tube, but the liquid and tube materials used!?!?!?! Huh....Whut?

@seasong7655 4 жыл бұрын

When the water is climbing the tube it gains potential energy, but where is this energy coming from?

@RKBrumbelow 3 жыл бұрын

He mentions the biggest clue for you, simply that thermal energy boosts the water to a higher gravitational potential energy, but in doing so it looses momentum/ kinetic energies so what you will see is a loss of temperature in the system directly related to the increase in gravitational potential energy.

@invalide 3 жыл бұрын

it's also how candles work and i think that's very sexy of it

@mingyeeleung5756 5 жыл бұрын

surface tension?

@jfuite 7 жыл бұрын

Why not show actual pictures of the phenomena instead of just talking about it?

@vectorscore21680 2 жыл бұрын

I guess you could do the experiments yourself, they’re not that complex

@jackyarnton1732 3 жыл бұрын

how does he write so effectively with a mouse this is abhuman

@sarbagyaratnakhatiwada3159 2 жыл бұрын

He actually got a touch pad writing device

@jackyarnton1732 2 жыл бұрын

@@sarbagyaratnakhatiwada3159 ak ok i'm an idiot ty XD

@ClasssicAri 7 жыл бұрын

But how come if you take a plastic comb over water, it still has capillary action.

@JasonVaysberg 6 жыл бұрын

Plastics are kinda a complicated chemistry topic and often times there are entire courses at unis on polymers, but basically because the short answer to your question that there are many different kinds of plastics made up of different chains of elements called polymers. There are many types of plastics, but a plastic water container is likely a different kind of plastic than the plastic of a comb. If that doesn't help: think about the idea that polymers can be made up of tons of different constituents and amounts of constituents -- like carbon, hydrogen, oxygen, nitrogen, sulfur, chlorine, fluorine, phosphorus, silicon, etc. These all have different differences in polarities across molecules.

@MrMdegmm 9 жыл бұрын

First comment :)

@penanutpenuatya 9 жыл бұрын

Lolno

@lawlerzwtf 8 жыл бұрын

That seemed like it was cut short lol

@Ohhh92 3 жыл бұрын

Im 14 and i dont understand😊

@labrat3305 5 жыл бұрын

i like your dipoles haha

@shadowpumper 6 жыл бұрын

who's here after the pyramid power plant?

@aes53 6 жыл бұрын

This is painful to watch. The silica surface is nothing like this guy thinks it is, it is completely covered with hydroxyl groups, in fact you have to go to high temperatures to get rid of them and they reappear instantly when exposed to the ambient environment. The wetting and the capillary forces are caused by the water hydrogen bonding to the silanols (Si-OH) groups on the surface.

@varunsharma4575 6 жыл бұрын

Why does it happen with other surface like towels, paper, etc.?

@yourlifeisagreatstory 5 жыл бұрын

The 13yr old voice in my head says: Imma start callin’ my junk Freddy Mercury because it’s bulging! The 17yr old nerd voice in my head says: My bulge puts the Hg in Huge!