 This is dialysis tubing and a dialysis tubing is a membrane that if we put a compound inside like water or molasses if the molecules are very large they can't pass through the little tiny holes in the membrane but if they're very small they'll pass through that's why it's called semi-permeable. Little things will pass through but not big things so what we're going to do to test that osmotic pressure inside and outside is we're going to use this as if it were a cell. We're going to take the molasses and pour into our dialysis tubing and then we're going to tie it we're going to make two like this one will use as our control the second one will put in a beaker of water. Two hours later let's see what our results are. You can see definite change in the volumes and if we move this around you can see that in this larger volume the molasses is not nearly as viscous so we have plenty of evidence to support the fact that the water molecules move through the dialysis tubing and it's diluted the molasses so the osmotic pressure was the driving force that brought the water in and this one remained unchanged.