Question

What is osmotic pressure? Name the experiment which can demonstrate it.

Answer 1

Osmotic Pressure:

1. The actual pressure developed in a solution when it is separated from pure water by the means of a semi-permeable membrane is known as osmotic pressure.
2. Osmotic pressure depends upon the number of solute particles present in the solution.
3. The higher the concentration of the solution, the greater will be the osmotic pressure.
4. It is also known as osmotic potential or solute potential.
5. Osmotic pressure can be demonstrated by the thistle funnel experiment.

Thistle funnel experiment:

1. In this experiment, a thistle funnel whose mouth is covered with a semipermeable membrane, is filled with sucrose solution.
2. It is then kept inverted in a beaker containing water.
3. The water diffuses across the membrane due to osmosis and raises the level of the solution in the funnel.
4. This movement of water inside the funnel can be prevented by applying pressure to the solution in the upper part of the funnel.
5. Hence, the pressure required to prevent the movement of water completely is called osmotic pressure.