Osmosis Practical Investigation
Ever wondered why chips go soggy when you add too much salt? This osmosis practical shows you exactly what's happening at a cellular level using potato cylinders and salt solutions.
The experiment is brilliantly simple: you're testing how different concentrations of salt solution affect potato mass. Your independent variable is the salt concentration (what you're changing), whilst your dependent variable is the percentage change in mass (what you're measuring). Keep everything else constant - potato size, solution volume, time, and temperature.
Here's the method that actually works: Use a cork borer to cut identical potato cylinders, then trim them to the same length with a knife. Dry and weigh each cylinder before placing them in boiling tubes with different salt concentrations (0%, 0.25%, 0.5%, 0.75%, and 1%). After a set time, remove them, dry carefully, and weigh again.
Top Tip: Always blot the potato cylinders dry before weighing - excess water on the surface will mess up your results completely!
The results table shows a clear pattern: higher salt concentrations cause greater mass loss. In pure water (0% salt), the potato stays the same mass. But in 1% salt solution, it loses 25% of its mass through osmosis - water leaves the potato cells to dilute the concentrated salt solution outside.