A journey of osmotic regulation. By: Noor Hason and Jacquelyn Wood

T HE H YPOTHESIS : If a hypotonic potato is placed in a hypertonic aqueous solution of sodium iodide, then the water from the potato should move into the surrounding solution in an attempt to dilute it.

T HE P ROCEDURE : Materials: five potato cores of various diameters, five cups appropriately labeled, a triple beam balance, iodized salt, a graduated cylinder and distilled water. 1. Collect all necessary materials. 2. Cut five various sizes of potato cores and measure and record their initial mass. 3. Make five aqueous solutions of 4% sodium iodide. 4. Place potato cores in the solutions for at least 25 min. to soak. 5. Remove potato from solutions. 6. Measure and record the final mass.

T HE E VIDENCE : Core SizeInitial Mass (g)Final Mass (g)Percent Mass %

T HE C ONCLUSION : The purpose of this lab was to observe how core size effected osmotic rate. The results of our lab were consistent with our hypothesis. As you can see in our data, all the potato core samples lost weight rather than gaining it. This is significant because it shows that the water from the potato moved into the surrounding solution. In the procedure of our lab, we might have had a few errors such as: reading the meniscus incorrectly, therefore resulting in a more concentrated salt solution. Another error that could have been made was not getting the lengths of the potatoes equal. Some things that our group would have done differently might be to use an electronic scale so as to ensure measurement accuracy. If possible, we would have thought it best to let the potato samples soak for a longer period of time. Something that we learned through this lab was that as the size of the potato increases, the amount of water that leaves the potato is less.