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Science 5: Osmosis 67 Views


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Description:

We're raisin the water content of raisins today with osmosis. Spoiler alert: even through they may look like grapes again, they're still going to taste like raisins. You've been warned.

Language:
English Language

Transcript

00:05

[Dino and Coop singing]

00:13

Raisins: you either love them, or hate them.

00:16

And if you hate them, keep it to yourself. [Raisins in the trash]

00:18

Raisins have feelings, too ya know.

00:20

But one thing raisins are good for is experimentation.

00:23

So the next time you encounter one of these little guys, try this: [Raisin jumping in front of some test tubes]

00:27

Put it in a bowl.

00:28

Fill the bowl with water.

00:29

Watch the raisin balloon up before your eyes. [The raisin swells]

00:32

Will it taste like a grape?

00:33

No.

00:34

This isn't Hogwarts.

00:35

C'mon. It's still a raisin.

00:36

But it is a pretty neat example of a process called osmosis.

00:40

Osmosis is the movement of water from a lower concentration to a higher concentration. [Coop pointing at a blackboard]

00:45

So let's go back to our raisin.

00:47

Here's the raisin...

00:48

…and here's the water.

00:49

The water is simply hanging out around the raisin.

00:52

What determines if the water will go into the raisin is how much “solute” is present. [Arrows showing the flow of water]

00:56

Solute just means any sort of substance dissolved into water. [Dino pointing at a blackboard]

00:59

Like when your dad puts a million sugar packets into his morning coffee. [Teaspoon of sugar going into coffee]

01:03

That sugar is a solute!

01:05

When something is plunged in water, the water molecules pass through cell membranes from

01:09

an area of low solute concentration into an area of high solute concentration.

01:14

The water moved into the raisin, since it had more solute, and it swells the raisin [Water molecules shown in the raisin]

01:18

up, making it bigger.

01:19

That's osmosis.

01:21

And guess what?

01:22

Osmosis is used by plants all the time.

01:24

They use it to take in water for themselves. [Plants next to a stream]

01:27

How selfish.

01:28

Anyway, if you've ever seen a dehydrated plant before, the stem might look all floppy and weak. [Plant drooping]

01:32

Water that plant, however, and osmosis occurs, allowing the water to move into the stem, [Water going into the plant stem]

01:37

stiffening it up.

01:38

That's osmosis, too.

01:39

Animal cells can also use osmosis – but there's a risk involved. [Chickens]

01:43

If too much water moves into the cell, that cell can burst, just like a water balloon

01:47

you left under the faucet for too long.

01:49

In cells, this is called “lysis.” [Water balloon explodes in the sink]

01:51

So if you take a cell with some water and solute in it...

01:54

…then place it into a hypotonic solution – which just means a solution that has less

01:58

solute and more water than that cell –

02:00

…then the water will move into the cell, increasing the pressure. [The cell expanding]

02:04

However, if you take the same cell and instead put it into a hypertonic solution – which

02:09

means a solution with more solute and less water...

02:12

Then the water will move out of the cell, leading to shrinking, or plasmolysis. [The cell gets smaller]

02:17

Sounds like some sort of alien technology, huh? [People running away from a laser gun]

02:20

Plasmolysis powered blaster pistols… [Aliens holding the pistols]

02:22

Anyway, you might think this is all a bunch of scientific nonsense with no real world

02:26

application, but consider this…

02:28

What do people do when they drop their iPhone into the toilet? [Phone falls in and turns off]

02:32

Well, after being totally grossed out, they usually fish it out and then place it into

02:36

a bag of rice, drawing the water out and saving their phone from imminent death. [Water molecules leaving the phone]

02:40

That's right, a cell phone saved, all thanks to Captain Osmosis.

02:45

Which even we'll admit is probably not the coolest superhero name in the world. [Guy wearing a mask and a shirt with a big O on it]

02:48

At least it's better than Captain Rice Bag… [Guy wearing a shirt with a big R on it]

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