Osmosis and Diffusion Lab 1
Dialysis tubing with clamps
Solutions of glucose, starch, protein and sodium chloride (NaCl)
250 mL beaker
Silver nitrate reagent
Triple beam balance
Procedure – Section A – Set-Up of Dialysis Tubing:
1. Use a piece of well soaked dialysis tubing (the “intestine”). Should be about 15 cm long. Fold one end over
about 2.5 cm and apply a clamp to the doubled region to seal the end of the tubing.
2. Open the other end of the tubing by rubbing the end between your finger and thumb. Slowly dispense 3 mL
of each of the following: protein, starch, glucose, and NaCl into the intestine.
3. Squeeze the air from the intestine. Fold the open end over about 2.5 cm and clamp it. Rinse the tubing in
tap water, blot it dry with a paper towel, and weigh the intestine. Record the weight in Table 1.
4. Place the weighed intestine in a 250 mL beaker then add tap water until the tubing is completely
Procedure – Section B – Sampling of Water Surrounding the Intestine and of Intestinal
1. Label 4 tubes as follows: G10, S10, P10, and N10. G = glucose, S = starch, P = protein, N = NaCl
2. Label four additional tubes as follows: G20, S20, P20, and N20. The 20 signifies that you will be sampling
water after 20 minutes has passed.
3. Allow the intestine to sit in the water in the beaker for 10 minutes. After 10 minutes, use a pipette to
transfer 20 drops of water from the beaker (outside the intestine into each of the four labeled test tubes
(G10, S10, P10, and N10). Place these tubes in your test tube rack and save them for later analysis.
4. Allow the intestine to sit in the water in the beaker for 10 more minutes. After this, use a pipette to take 20
drops of water from the beaker to your labeled test tubes (G20, S20, P20, and N20). Place these into your
test tube rack and save them for later analysis.
5. Remove the intestine from the beaker, gently pat it dry with paper towels and weigh it. Record the weight
in Table 1 below.
6. Label 4 more tubes as follows: G-IC, S-IC, P-IC, and N-IC. (IC = intestinal content)
7. Open the intestine and pour the contents into a clean beaker. Use a clean pipette to add 20 drops of the
intestinal contents to each of the test tubes (G-IC, S-IC, P-IC, and N-IC). Place these tubes into your test
tube rack (TTR) and save them for later analysis. Osmosis and Diffusion Lab 2
Procedure – Section C – Nutrient Testing:
1. Set up of negative controls:
a. Label 4 test tubes as follows: G-, S-, P-, and N-.
b. Add 20 drops distilled water to each of these tubes.