1. Based on your observations, which substance moved, the iodine or the starch? Based on our observations, the iodine diffused into the dialysis bag. Diffusion is the movement of substances from high concentration to areas of low concentration. The dialysis was selectively permeable, which meant that substances such as the iodine were able to pass through. Based on the color change of the starch as well as the change in mass, the solution within the dialysis was hypotonic to the solution in the beaker. Therefore, the iodine was hypertonic to the dialysis, which caused the movement of the iodine. 2. How did you determine this? We determined this based on the color change in the bag. The starch in the bag changed to a purple color after around 20 minutes of waiting. This showed that the solution in the beaker was hypertonic to the solution within the dialysis. Since the starch cannot pass through the bag, then it means that the concentration gradient between the dialysis bag and the beaker allowed the iodine to move into the bag. Iodine is an indicator, and changes to purple whenever it is in the presence of starch. Because the beaker is hypertonic to the bag, the iodine had to diffuse from an area of high concentration to an area of low concentration. Because …show more content…
The plastic baggie was permeable to which substance? The plastic baggie was permeable to the iodine because the starch solution reacted by color change when iodine permeated the “cell membrane”. As a result of this, the concentration gradient allowed for the iodine to pass through the dialysis bag and react with the starch solution. However, the dialysis bag was not permeable to the starch solution, as evident by the lack of color change by the iodine solution in the beaker. As a result, the dialysis bag is selectively permeable, allowing for some substances such as iodine to move while preventing other substances such as the starch solution to move. 4. Is the plastic baggie selectively