Osmosis experiments
Visking tubing is an artificial The property of a membrane that controls the movement of molecules depending on their size. membrane:
- smaller molecules like water and A simple sugar used by cells for respiration. pass through its microscopic holes
- larger molecules like A type of carbohydrate. Plants can turn the glucose produced in photosynthesis into starch for storage, and turn it back into glucose when it is needed for respiration. and A disaccharide made from glucose and fructose. It is used as table sugar. cannot pass through it
This slideshow shows a typical experiment using Visking tubing and sucrose solution.
Image caption, Visking tubing experiment
The Visking tubing is the selectively permeable membrane. Water moves by osmosis from the high water concentration (dilute solution) in the beaker into the low water concentration (concentrated solution) in the Visking tubing across the membrane, increasing the volume of liquid in the Visking tubing, which forces liquid up the capillary tube.
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