Experiment to demonstrate osmosis (LC 2026) (Leaving Cert Biology): Revision Notes
📚 Revision Notes
Experiment to demonstrate osmosis
infoNote
Osmosis: the movement of water molecules from an area of high water concentration to an area of low water concentration across a semi-permeable membrane.
Equipment needed:
- Visking tubing (2 strips)
- Sugar solution (80%)
- Distilled water (control)
- Beakers
- Mass balance
- Water
Method:
- Soak two strips of visking tubing in water to soften them.
- Tie a knot on one end of each strip.
- Half-fill one piece of tubing with a sugar solution and the other with distilled water (control).
- Remove any air from the tubing and tie a knot on the open end of each tube.
- Observe and record the turgidity of each tube.
- Use a mass balance to weigh each piece of tubing. Record the weight.
- Place each piece of tubing in separate beakers of water.
- Leave for 15 minutes.
- Remove the tubes from the beakers.
- Reweigh each tube and record the new weight.
- Observe and record the turgidity of each tube.
Control
Experiment
Results:
| Tube Content | Starting turgidity | Ending turgidity | Starting mass | Ending mass |
|---|---|---|---|---|
| Sugar Solution | Not fully turgid | Fully turgid (fuller appearance) | 10.8g | 15.2g |
| Distilled Water | Not fully turgid | Not fully turgid (no change in appearance) | 10.8g | 10.8g |
Conclusion**:**
The visking tubing containing the sugar solution gained mass as osmosis occurred. The control tubing with distilled water did not change mass, indicating that no osmosis occurred.