If I wanted to determine if a membrane was permeable only to water, what experiment could I do?
To determine if a membrane is selectively permeable to water, you can conduct an experiment called "osmosis." Osmosis is the movement of solvent molecules (in this case, water) through a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.
Here's a step-by-step procedure to test the membrane's permeability to water:
1. Obtain a selectively permeable membrane. This can be a dialysis membrane or any other membrane known to allow water to pass through while preventing the passage of solute particles.
2. Create two equal-sized solutions: one with a known solute concentration and another with a higher unknown solute concentration. The known solute concentration solution will serve as the control.
3. Fill two separate containers, such as beakers, with the solutions you created. Place each container next to each other.
4. Secure the selectively permeable membrane between the two containers, ensuring it fully separates the solutions and forms a seal.
5. Monitor the two solutions over a specific period, typically several hours or overnight.
6. Observe the changes in volume or mass of each solution over time. If the membrane is selectively permeable to water, you would expect the solution with the higher solute concentration to experience an increase in volume or mass due to the movement of water through the membrane.
7. Analyze the results. If the solution with the higher solute concentration shows a noticeable increase in volume or mass compared to the control solution, it indicates that water successfully passed through the membrane. Therefore, the membrane can be considered permeable to water.
Keep in mind that osmosis is a slow process, so you may require a longer observation period to detect significant changes. Additionally, controlling variables such as temperature and pressure is crucial to ensure accurate results.