Hi. It's Mr. Andersen and today I'm going to show you a quick little osmosis
demo that I set up in my classroom. But before I do that I should probably talk a little
bit about what osmosis is. And so osmosis is simply diffusion or the movement of water
from an area of high water concentration to low water concentration, across a semipermeable
membrane. So what does that mean? Well if you look right here in this U-Tube, that's
what this is called, this would be a semi-permeable membrane. And what that means is that it will
only allow a few things to move through. And so you can see right here that the water molecules
are small enough that they can pass through, but the solute molecules aren't. Solute molecules
can be sugar. Could be ions. But essentially can't make it through. They are too big. And
so in relation to this side, the left side here we would call the hypertonic side. What
hypertonic means is greater levels of solutes. And that means over on here this is in relation
is going to be called the hypotonic solution. In other words there's greater solute concentration
on this side then there is over here. And so these are in relation to each other. And
so what does that really mean? Well if we were to zoom at the molecular level all of
the water molecules are going to actually stick to the this solute. So the water molecules
are going to grab on to that. And since the water molecules are grabbing on to the solutes,
there's not going to be a lot of water on this side. And so we're going to say that
the hypertonic side is actually going to be an area where there's low water concentration.
So over here there's less solutes. So there's less water molecules grabbing on to the solutes.
And so the water is going to flow in that direction. And so however you want to think
about it is the water from an area of high water concentration to low or is the water
flowing towards a hypertonic area? Either of those, it doesn't matter. As long as you
know which way the water is going to flow. So what's going to happen to the water Well
the water is eventually going to flow over to the side until the concentration of water
on either side of that semi permeable membrane is exactly the same. At this point we would
say on either side it is now isotonic. If I can spell that right. Isotonic means that
water is still flowing back and forth but it's flowing back at an equal rate. Now if
you're to think about this, if you were to watch this, it would seem somewhat magical
as the water is just moving up on this side, just kind of against gravity and dropping
on this side. Because you can't see the solutes. And so that's pretty cool. So let me show
you the set up that I did in class. In this osmosis demo, let me find a good color, right
here I have dialysis tubing. Dialysis tubing has these tiny little holes in it. So if I
were to trace it out, we've got dialysis tubing here. Kind of tied it in the knot at the bottom.
And so it goes all the way up here. And then as we move up the dialysis tubing is empty
up here. But it's tied all the way up to a big ring stand at the top. So the dialysis
tubing is filled down here. Now what's it filled with? It's filled with corn syrup here.
And so that corn syrup is going to have a high concentration of solute. In this case
it's going to be sucrose or sugar. Outside of that, right out here we have water. We
have distilled water. And so if we look at these two in relation to each other, which
of the following is hypertonic? And which of the following is hypotonic? Well the hypertonic
is going to be the area with more sugar or more solute. And so in this case that's going
to be the corn syrup. And so we should have a flow of water in that direction. And so
I'm going to turn on the video and then speed it up a little bit. And so you can watch it.
And so you can see the magic of osmosis.