Osmosis is defined as the movement of water molecules from a region of their high concentration to a
region of their lower concentration via a semi permeable membrane.
A semi permeable or selectivity permeable membrane is one which can allow the passage of some
material to occur and prevent others from passing across it e.g. visking–tubing, cell membrane which
allows the passage of all materials across it is said to bea freely permeable membrane
 
An experiment to demonstrate osmosis
 
Aim : To demonstrate osmosis in non living tissues (osmometer)
 
Materials

• Visking tubing or cellophane or dialysis tubing
• Thistle funnel
• Sugar solution
• Distilled water
• Beaker
• Stand/clamp

Procedures
50cc of distilled water is poured in a beaker. The mouth of thistle is tightly covered with a visking tubing
(a semi permeable membrane). This is filled with a strong solution .Thistle funnel containing the sugar
solution is lowered into the beaker and clamped vertically. The level of sugar solution in the funnel is
marked as the first level
 
Diagram
 
Observation
After 2 hours the sugar solution in the thistle is found to have risen upward to level 2 .The water level in
the beaker slightly falls down.
 
Conclusion
Water molecules moved from the beaker where they are of a high concentration to the sugar solution in
the thistle funnel via semi–permeable membrane by osmosis causing a risen in the level of solution in the thistle funnel

 
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