How Do You Do a Lab for Osmosis With Potatoes?

A lab experiment for osmosis with potatoes involves putting half a potato in plain water and the other half in salt water and observing the difference in appearance. Osmosis is defined as the manner in which molecules pass through a membrane into a more concentrated solution.

Only a few supplies are required for this experiment. Gather a large potato, knife, two plastic plates, salt and water.

  1. Prepare the water solution
  2. Pour plain water into one plate. In the other plate, add water and 2 tablespoons of salt and mix until the salt is dissolved.
  3. Add the potatoes
  4. Cut the potato in half lengthwise with the knife. Lay one half in the dish with the water, cut side down. Do the same with the other half of the potato in the dish with the salted water. Let the potatoes sit in the water for a few hours.
  5. Observe the differences
  6. Once time is up, flip the potatoes over to observe the changes on the cut side.

The potato that was in plain water will not look much different than before, except it may be a bit more rigid. That is because the plain water moved into the potato’s cells. The potato in the salt water will be slightly discolored, soft and flexible. This is because the contents of the potato’s cells moved out of the potato and into the salt water by osmosis.