Osmotic pressure can be measured using a relatively simple setup involving a semipermeable membrane.
Measuring Osmotic Pressure: A Simple Method
One straightforward method involves the following setup (as illustrated conceptually in Figure 2 of the provided reference):
- Preparation: A funnel-shaped tube's wider end is covered with a semipermeable membrane. This membrane allows solvent molecules to pass through but restricts the passage of solute molecules.
- Filling the Tube: The tube is filled with the solution for which osmotic pressure needs to be measured.
- Immersion: The filled tube is then placed in a container of the pure solvent.
- Observation: Due to osmosis, the solvent molecules will move across the membrane into the solution, causing the solution level within the tube to rise.
- Equilibrium: The solution level will continue to rise until it reaches a maximum height. At this point, the hydrostatic pressure exerted by the column of solution balances the osmotic pressure.
- Measurement: The height of the solution column above the solvent level is then measured. This height is directly related to the osmotic pressure of the solution.
