The Effect of Concentrations of Starch and Sugar Solutions on Synthetic Semi-
Permeable Membranes


By: Jamie Hardy

Question: Is dialysis tubing selectively permeable?

Hypothesis: If one has dialysis tubing, which is dipped in water, filled with
Gatorade and starch and is left for 15 minutes, the sugar in the Gatorade will
exit the dialysis and into the water. So the dialysis is semi-permeable.

Materials: 16 cm dialysis tubing beaker cylinder test tubes transfer pipettes
Gatorade Starch solution 10 g/1000 ml water Benedict's Solution Iodine
Solution string ring stand water bath boiling chips goggles

Scientific Method: 1. Each group will make up a Gatorade solution as follows:
Group 1 1.0 M 3.4 g/10 ml
Group 2 0.5 M 1.7 g/10 ml
Group 3 0.5 M 1.7 g/10 ml
Group 4 0.2 M 0.7 g/10 ml
Group 5 0.2 M 0.7 g/10 ml

NB: Tare the balance.
Tare the balance with a test tube inside a beaker.
Add the amount to the tube.
Vortex, gradually turning the speed up.
Heat in a water bath.
Cool the tube. 2. Wet the dialysis tubing with the beaker of distilled
water. 3. Twist one end of the tubing. 4. Fold the twisted end over on itself. 5.
Tie a tight knot. Leave the extra string. 6. Insert the transfer pipette (cut
off top) about one third of the way into the tubing. 7. Tie a knot securely
around the transfer pipette. Leave the extra string. 8. Add two transfer
pipettes (two squirts) of the Gatorade solution to the tubing. 9. Add two
transfer pipettes (two squirts) of the starch solution to the tubing. 10. If you
spilled any solutions while transferring, carefully rinse the tubing. 11. Fill
the cylinder with distilled water to about 2.54 cm from the top. 12. Place the
tubing into the cylinder of water. 13. Rest the apparatus against the ring stand.
14. Note the height of the water in the tube. 15. Record the time the tube was
placed into the cylinder (it will stay for about 20 minutes)
Time tubing was placed into cylinder: 1:15.00 p.m.
Time tubing was taken out of cylinder: 1:31.12.87 16. Note any changes
in the height of the water in the transfer pipette.
The height of the water in the transfer pipette was that it did not
change. Observations and Data: Tests:
Positive Negative Test for starch and Iodine Solution
blue black clear yellow Test for Gatorade and Benedict's Solution
orange/green clear blue 17. Using transfer pipettes and dry
test tubes, test the solution that has been holding the tubing for Gatorade and
starch.
Test each separately.
Run a control for each.
Test each of the original solutions with Benedict's and Iodine solutions.

18. Record Observations:
When starch is added to Iodine Solution it turns clear yellow and when
Gatorade and Benedict's Solution are mixed it turns orange. The Gatorade
solution smells like burnt Gatorade and the starch solution smells like a very
dull baby powder. 19. Test a known glucose solution with Benedict's and Iodine
solutions. 20. Record observations:
The color of the glucose did not change when mixed with Benedict's and
Iodine Solutions. The color did get greyer though.

Discussion:
In the observations unit of the lab report it explains that the test on
starch added to Iodine Solution and Gatorade added to Benedict's Solution the
Gatorade solution was a thick orange color and the starch solution was a very
clear yellow. The Gatorade Solution smelled like something was burnt and placed
in the solution and the starch solution smelled like a very dull baby powder.
When the Gatorade solution was placed over the flame the solution bubbled to the
top of the test tube and almost went over.

Conclusion:
My hypothesis, "If one has dialysis tubing, which is dipped in water,
filled with Gatorade and starch and is left for 15 minutes, the sugar in the
Gatorade will exit the dialysis and into the water. So the dialysis is semi-
-permeable.", was proven correct. The tubing is semi-permeable.

Category: Science