Mixtures
Diffusion & Osmosis
Osmosis in RBCs

Lab 5 - Diffusion and Osmosis Questions

These labs presume you have completed the membrane transport lectures. If you have not go back and do those first.
In this experiment, you will examine the diffusion of small molecules through dialysis tubing, a selectively permeable membrane. Dialysis tubing contains microscopic pores that allow molecules of a certain size to pass through. Small solute molecules and water molecules can move freely through, but larger molecules will not. The movement of a solute through a selectively permeable membrane is called dialysis. The size of the minute pores in the dialysis tubing determines which substances can pass through the membrane.

A starch water mixture will be placed inside a bag of dialysis tubing. The tubing is clipped to seal the bag from leakage. Distilled water and iodine will be placed inside a beaker, and the dialysis bag will sit in this beaker. Iodine is an amber colored. When mixed together iodine and starch turn a purplish / black color, depending on the concentration.

Additionally, the bagged gained weight. With water being the only significant source of weight gain.
Questions

Using a periodic table, what is the molecular weight (size) of Iodine?
Which is bigger, starch or iodine? Why or how do you know?
Which molecules were permeable?
Was the net movement of water into or out of the bag.
Did diffusion occur?
Did osmosis occur?
At the beginning of the experiment, was the bag solution hypertonic, hypotonic or istonic?