Osmosis

Practical Report

Experiment 4 & 5 Diffusion and Osmosis

Experiment: 5 Osmosis- The movement of water

Aim: To observe the effects of the movement of water into and out of cells.

Hypothesis: I think the potato in the salt water will become soft and the potato in the distilled water will stay firm.

Method:

1. The potato was peeled and cut in to two 2cm cubes.

2. One potato was placed in a beaker of distilled water and the other into a beaker of salt solution.

3. The potatoes were left in the solution overnight.

4. The potato cubes were then taken out of the liquids and tested.

Results: 1 2

Discussion: The potato left in the distilled water became hard, while the potato in the salt water became soft. These results are due to diffusion of water molecules through the cell membranes of the potato cells. Osmosis occurred in the cell because the cell membranes are semi-permeable. The cells in the potato contained 90% water when the potato was placed in distilled water because water molecules diffused into the cell. The water molecules moved into a lower concentration which made the potato firm and larger. When the potato was placed in the salt solution where there is only 80% water, the water diffused out because it was at a higher concentration in the cell which made the potato softer and smaller.