1. Observing Diffusion and Osmosis (pg 29-31)
Student Name
Date
Observing Diffusion and Osmosis (pg 29-31)
Question
Which molecules moves through a dialysis membrane?
Hypothesis
If starch can fit through the dialysis tubing, then the water outside should turn black
Materials
See page 29
Procedures
Do procedures 2,3,5,6,7
Analysis
Do B-F
Evaluation
Do I
Conclusion
Was your Hypothesis supported or rejected? Explain

2. Question
Which molecules moves through a dialysis membrane?

3. Hypothesis
If starch can fit through the dialysis tubing, then the water outside should turn black

4. Materials
See page 29

5. Procedures
Do 2,3,5,6,7
6. Black occurs inside the bag.

6. Analysis b. Iodine indicates the presence of starch.
c. Some molecules that move by diffusion are perfume, oxygen, carbon dioxide, water.
d. The tube with tap water acted as a control.
e. If dialysis tubing were permeable, we would have seen black outside the bag.

7. Analysis f. Water osmoses both in and out of the bag equally
Water osmoses into the bag (The bag swells)
Water osmoses out of the bag (The bag shrinks)

8. Evaluation
I. Some limitations of dialysis tubing are that the pores are all the same size and not selectively permeable. (i.e. the can not grab onto certain molecules and pull them in)

9. Conclusion
The Hypothesis was supported. The iodine osmosed into the bag turning the starch black. The starch was too big to leave the bag.