Diffusion, Science Lab Green

         On October 13, 2011 in a science lab, an experiment was done. The labs purpose was to show how the cell membrane allows certain substances to travel in and travel out. The experiment involved predicting what might happen; such as if the plastic baggie were permeable to starch, the starch would move into the bag. Another prediction was that if the bag was permeable to iodine, it would move out of the bag; if the plastic baggie was permeable to iodine, the solution inside the plastic baggie would turn purple and the solution in the beaker would stay the same. The last prediction made was that if the baggie was permeable to starch, the solution in the baggie would turn golden and the solution in the beaker would turn purple. What also happened was diffusion (the process by which molecules move from an area of high concentration to an area of low concentration) and osmosis (the diffusion of water molecules through a selectively permeable membrane). The indicator (a substance that changes color in the presence of the substance it indicates) iodine was used on starch and it made the starch solution in the baggie hypertonic (high concentration) and the beaker became hypotonic (lower concentration) in relation to starch. None of the solutions were isotonic (equal concentration).

         The lab was done easily. Filling a baggie with a teaspoon of cornstarch and half a cup of water and tying the bag? Not a problem. Filling a beaker halfway with water and adding then drops of iodine? Hah! Like that would ever be a dilemma. Placing the baggie in the in the beaker so the cornstarch is completely in the iodine/water mixture? Kind of cool. But waiting fifteen minutes to see what would happen?! That was almost forever! But the experiment was worth the wait.

      This experiment, like written before, involves diffusion. Some examples of diffusion are cigarette smoke (it diffuses into the air and spreads around the room), a drop of food coloring in water (it gradually diffuses throughout the water), oxygen (diffuses from the air sacs in lungs into blood capillaries), and helium (it diffuses through the membrane of a balloon, causing the balloon the stop floating).