October 11, 2011 - Diffusion Experiment

In science class yesterday, we completed a diffusion experiment. To begin, a beaker was filled halfway with water. Then, a teaspoon of corn starch was placed into a plastic bag, which was secured shut and submerged in the water in the beaker. The last step of the preparation was to drop iodine into the water. After sitting for about fifteen minutes, the iodine should have diffused into the plastic bag, which is permeable to liquid substances. The mixture of iodine and water should have entered the plastic bag, changing the starch from a translucent white color to a dark purple color. However, only a small portion of the bag's contents were changed to the purple color, and it was a lighter shade than expected. This may have been because the iodine was not given enough time to complete the full process of osmosis. When this experiment was put in place for an extended period of time by Mrs. Rousseau, the process worked out, and the iodine diffused into the starch. Overall, this experiment was a great way to learn about osmosis and diffusion.