Diffuse Through The Dialysis Bag's Membrane example essay topic

Diffusion LabProblemWill starch, water, glucose, iodine or a combination of the above diffuse across the membrane of the dialysis bag causing the bag to either expand or shrivel? Hypothesis & Strategy I believe that the smaller molecules, such as glucose and water will diffuse through the dialysis bag's membrane causing it to expand, due to the concentration gradient. I would test this hypothesis by filling the bag with a solution consisting of water, glucose and starch, tie it off and weigh it. I would then place the bag in a beaker of water and let it sit for a day.

Then I would reweigh the bag. Materials. Dialysis Tubing. Glucose Starch Solution, 15 mL.

IKI Solution, 5 mL. 4 Glucose Indicator Strips. 1 Graduated Cylinder. 1 Plastic Cup, 250 mL Experimental Procedure 1. Pour 15 mL prepared glucose / starch solution into the graduated cylinder. 2.

Get a piece of tubing and use a sting to tie a knot on one end of the tubing. 3. Open the tubing and pour 15 mL of the glucose / starch solution into the tubing. 4. Determine the initial glucose content in the tubing by using the glucose indicator strip. Record the data in Table 1.5.

Tie another not at the other end, leaving room for expansion 6. Record the color of the solution in the bag in Table 1.7. Fill a 250 mL beaker approximately 2/3 full with distilled water. Add 5 mL of iodine to the beaker. 8.

Record the color of the solution in Table 1.9. Determine the beaker glucose content using the glucose indicator strip and record the data in Table 1.10. Completely immerse the dialysis bag in the solution in the beaker. 11. Wait at least 30 minutes or until there is a noticeable change in the color of the solution in either the beaker or the dialysis bag. 12.

Remove the dialysis bag from the beaker reweigh it and record the final color and glucose content of the dialysis bag and the beaker. Record this data in Table 1.13. Wash your hands and clean up lab area. Observations Color Glucose Content Bag Time Dialysis Bag Beaker Dialysis Bag Beaker Weight Start Cloudy white Gold 500 mg / dl Negative 49.5 after 30 minutes Cloudy Purple Clear 100 mg / dl 100 mg / dl 50.9 g Analysis 1. What do your observations tell you about the presence of glucose, starch, and IKI in the dialysis bag and the beaker before and after the experiment? Before the experiment the dialysis bag had water with glucose and starch dissolved in it, while the solution in the beaker consisted of water and iodine.

After the experiment the iodine had diffused into the bag while the glucose had diffused out of the bag. This is evident because at the conclusion of the experiment the bag was purple due to the reaction of iodine and starch. The glucose content of the beaker was higher at the end of the experiment than in the beginning, proving that the glucose had diffused into the beaker from the bag. 2.

What can you conclude about the permeability of the dialysis bag membrane? Which compounds were able to diffuse through the membrane? Which were not? Why were only some able to pass through? The dialysis bag's membrane was a selectively permeable membrane. Iodine, glucose and water were able to diffuse through the membrane while starch was not able.

This occurred because while iodine, water and glucose molecules are small enough to diffuse through the membrane, disaccharides like starch are too large to diffuse through the membrane. 3. Was there more or less water in the dialysis bag at the conclusion of the experiment? Why? There was more water in the bag at the conclusion of the experiment because there was a higher concentration of water outside the bag than inside, creating a concentration gradient. 4.

Why did you weigh the bag? Did the weight increase or decrease? What does this prove? We weighed the bag so that we would know if there was any increase in weight or water in the bag at the conclusion of the experiment. The weight increased.

This proves that the bag's membrane was selectively permeable. Conclusion After doing the experiment I could clearly see that the iodine moved in to the dialysis bag, and some of the glucose move out of the bag to be at equilibrium. We found this out because of how the test strips came out positive for the solution inside the beaker..