Tonicity Lab

Tonicity Lab

Performed by: Danielle Dusterhus, Itati Fernandez, and Salvador Flores

Introduction:

We will be doing this experiment to demonstrate osmosis. Osmosis is when water spreads from an area of low concentration to an area of high concentration. Osmosis is different than diffusion because in diffusion, solutes spread from an area of high concentration to low concentration. The solution with a higher salt concentration is called hypertonic. If the solution has a lower salt concentration it is hypotonic. If the solution has the same concentration it is isotonic. Our hypothesis is that if the potato is placed into distilled water, the concentration of water outside of the cell will be greater that the concentration of the water inside the cell. There will be a net movement of water from the area of high concentration to the area of low concentration and as a result of this the cell will contain more water and cause the potato to expand. If the potato is placed into a salt solution, the water will be greater inside the cell than outside, osmosis will take place and the water will move from the area of high concentration (inside the cell) to an area of low concentration (outside the cell). This will cause the potato to shrink as it loses water.

Materials & Methods:

The materials that were used for the experiment was a ruler, potato, distilled water, a timer, salt, two clear-plastic cups, and a knife. To begin the experiment, one of my group members cut two cubed-shaped pieces from the potato. We poured about ¾ of a cup of water into the two cups and mixed 3 tbs of salt into one of the cups. Next we examined and measured the potato pieces using the cm unit. Then we placed each piece in a cup and observed for changes in the potato pieces for 30 minutes. Once the 30 minutes passed, we took the potato pieces out, measured them and scanned the potato for any changes. After completing the experiment, we wrote down our results and cleaned our area....