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.
