Day 5: Finishing Difussion/Osmosis Lab

On day 5, we finished up the final parts of he diffusion/osmosis lab. But first, we reviewed general graphing skills and how to apply those to find molarity.

For Part 1 of the lab, we recorded the original volume and surface area of a "cell" (we used agar). We cut two sets of small cubes, middle-size cubes, and large cubes. Then, we added KI to some and NaOH to the rest. After letting them sit for about 15 min, we again calculated the volume and surface area. The purpose of his experiment was to observe the time rate of diffusion of different substances and how it is affected by volume and surface. Here are the results:

For Part 2 of the lab, we tested how glucose and starch would diffuse through a semipermeable membrane.  Here was my group's hypothesis:

We filled a diffusion tube with a solution of glucose and starch and tested for glucose with a test strip. We placed the tube in boiling water, and after we let it set, we took a pipette full of the water and add it to a test tube. We then added a benedict solution (to test for glucose) and put it back in the boiling water. The solution in the tube turned orange, which indicates that there was glucose in the solution. Then we added iodine to the water and the solution inside the cell turned dark blue/purple which means that the starch diffused into the cell  From this we can see that our hypothesis was supported, because only the glucose molecule diffused through the cell into the beaker because it is a smaller molecule than the starch.