Question

which molecules NaCl, starch or glucose passed through the dialysis tubing into the surrounding solution?
which one remained inside of the dialysis tubing?
which of the molecules passed most rapidly through the tubing?

6. Which molecule(s) (NaCl, starch, or alucose) passed through the dialysis tubing into the surrounding solution? How do you know? 7. Which molecule(s) (NaCl, starch, glucose) remained inside of the dialysis tubing? 8. Which of the molecules passed most rapidly through the tubing? How do you know?

Answer 1

ANS-This experiment was conducted to investigate the selective permeability of dialysis tubing. The permeability of the tubing to glucose, starch and iodine (potassium iodide) was tested. *****The dialysis tubing was clipped to form a bag so that glucose and starch was fed into the bag through the other end, and was also clipped to avoid the seeping of the solution. Water with several drops of iodine added to it until it was visibly yellow-amber was added to a 400ml beaker. ****The bag was then placed in the beaker, which was stirred with a magnetic stirrer. It was left there for 30 minutes. It was seen that the color of the solution in the bag changed to blue-black color, this showed that iodine was able to pass through the membrane into the bag. The solution in the beaker became pale yellow-amber, this showed that starch didn’t pass through the membrane into the beaker. To confirm the presence of glucose in the beaker and also the bag, a Benedict test was performed on the solutions including tap water (control) too. The beaker solution turned into light brown color after Benedict solution was added to it and suspended in water bath for 10 minutes. The bag solution also changed to brown color, while tap water remained blue. This experiment showed that dialysis tubing is selective in its permeability to molecules. It was permeable to glucose and iodine but not starch and NaCl   

Q-1 which molecules NaCl, starch or glucose passed through the dialysis tubing into the surrounding solution? ANS- Glucose

Q-2. which one remained inside of the dialysis tubing? ANS- Starch[, starch molecules did not travel through the dialysis tubing into the water. However, there is a purple-black color inside the tubing. Because iodine molecules traveled into the dialysis tubing and reacted with the starch molecules.] Q-3.which of the molecules passed most rapidly through the tubing? ANS- Glucose [please read above experiment] THANKS YOU VERY MUCH