Diffusion and Osmosis lab

     
  Diffusion and Osmosis are important to any living organism, because water and certain solutes move in and out of cells by these processes. During these two processes molecules only more from regions of higher concentration to lower concentration. The way this works is cells often need to absorb molecules from regions in which the concentration of the molecules may be lower than the concentration already inside the cell. Absorption of glucose from the blood frequently occurs under these circumstances.Diffusion and Osmosis do not require any added energy. In this experiment we measured diffusion of small molecules through a selectively permeable membrane (dialysis tubing). What is Dialysis tubing? Dialysis tubing is made of a membrane contain gin tiny pores. The size in the pores is what determines what molecules can exit or enter the bag.  For this experiment we used iodine,starch, dialysis bag, sting, beaker and water. 
      The first step to this was we opened the dialysis bag. On one end we tied a string to it so it stayed closed. After tying it closed we got the starch and put about three droplets full of it into the dialysis bag.  We than tied the top with sting so the starch wouldn't empty out. Next we filled up the beaker with water from the sink about half way and added Iodine into the water until it turned a dark yellow color. Next we added the Dialysis bag filled with starch into the water and iodine. We let the bag sit in the solution until the next class day(about 24 hours). 
      When we came into the class the next day after the letting the starch sit in the mixture of water and iodine  we looked to make observations about what happened. The solution of water and iodine was not a dark yellow color any more it was clear. After pulling the dialysis tube out of the water it had a purplish color at the bottom. 
     As a class and group we came up with the conclusion that the Iodine reacted with the starch in the Dialysis bag. Which made the Iodine enter the bag through its pores. This process would be the Osmosis part because the Iodine entered the bag. The Glucose from the starch exited the bag into the water which was diffusion.