How do you conduct a practical investigation on osmosis?

You can conduct a practical investigation on osmosis using a potato, salt solution, and water.

To start, you'll need a potato, salt, water, a knife, a ruler, a weighing scale, and six beakers. First, cut six equal-sized pieces of potato. Measure and record their initial lengths and weights. Fill three beakers with water and the other three with a salt solution. Place one potato piece in each beaker and leave them for a few hours or overnight.

The next day, remove the potato pieces from the beakers. Dry them gently with a paper towel to remove any excess liquid. Measure and record their final lengths and weights. The potato pieces in the salt solution should have decreased in size and weight, while those in the water should have increased. This is due to osmosis, the movement of water molecules from an area of higher concentration (the potato) to an area of lower concentration (the salt solution), through a semi-permeable membrane (the potato skin).

To analyse the results, calculate the percentage change in length and weight for each potato piece. This can be done using the formula: (final measurement - initial measurement) / initial measurement x 100%. Plot these values on a graph, with the type of solution (water or salt) on the x-axis and the percentage change on the y-axis. The graph should show a clear difference between the potato pieces in water and those in the salt solution, demonstrating the effect of osmosis.

Remember, it's important to keep all other variables constant (e.g., temperature, size of potato pieces, concentration of salt solution) to ensure a fair test. Also, repeat the experiment several times to confirm your results. This practical investigation is a simple yet effective way to observe and understand osmosis.