Osmosis Lab
Name: ___________________________
Purpose: To observe the movement of water across a membrane.
Materials:
Water
5% sucrose solution
20% sucrose solution
40% sucrose solution
Dialysis tubing
Graduated cylinder
Funnel
5 beakers
Methods:
1. Take four 15 cm strips of dialysis tubing and soak them in a beaker of water for 2 minutes.
2. Tie one end of the dialysis tube off (like a balloon).
3. Rub the other end between your fingers to open up the tube. Using the graduated cylinder measure
out 10 mL of water and pour it all into the dialysis tube with the aid of a funnel.
4. Tie off the other end of the dialysis tube.
5. Pat the dialysis tube dry.
6. Take the mass of the dialysis tube and record it in the table.
7. Place the dialysis tube in a clean, dry beaker marked “Water Only”
8. Repeat steps 2 – 7, only use 5% sucrose solution instead of water. Label beaker accordingly.
9. Repeat steps 2 – 7, only use 20% sucrose solution instead of water. Label beaker accordingly
10. Repeat steps 2 – 7, only use 30% sucrose solution instead of water. Label beaker accordingly
11. Add 200 mL of water to each beaker and let stand for 20 min.
12. At the end of the 20 min. remove the “Water Only” dialysis tube. Pat it dry and find its new mass.
Record this in the table.
13. Repeat step 12 for the other 3 dialysis tubes.
14. Change in mass as a percent using the following equation. Record these values in the chart.
% mass change = mass after – mass before x 100
mass before
15. Put all of the dialysis tubes in the plastic bag provided by the teacher.
16. Rinse the beakers, graduated cylinder and funnel, then return them to where you found them.
Observations:
Table 1: Osmosis through dialysis tubing
Tube Contents
Mass Before (g)
Water Only
5% Sucrose Solution
20% Sucrose Solution
30% Sucrose Solution
Mass After (g)
% Mass Change
Conclusion:
Look at the % mass change for each solution. Explain the pattern that you see (remember this lab is
based on osmosis).