Osmosis Lab

Osmosis of Sucrose Solutions of Different Molarities Through Dialysis Tubing (a Semi-Permeable Membrane)


  I. DESIGN
      A. PROBLEM/RESEARCH QUESTION
  1. How does increasing molarity of sucrose affect osmosis through dialysis tubing?

      B. VARIABLES
        1. The independent variable in this lab is the molarity of sucrose each dialysis bag is filled with. The time (30 minutes), the temperature (23C) and the type of dialysis tubing used are all constants.
        2. The dependent variable is the final mass of the dialysis bag.
        3. The control in the experiment is distilled water, as it does not contain sucrose solution.

      C. MATERIALS NEEDED
        4. Five 30 cm strips of dialysis tubing
        5. Five clear plastic cups
        6. 10 pieces of yarn
        7. Distilled water
        8. Sucrose solutions (with molarities of: 0.2, 0.4, 0.6, and 0.8)
        9. Calculator
        10. Electrical balance
        11. Clock
        12. Beaker
        13. Funnel
        14. Graduate cylinder
        15. Rag
        16. Sharpie

      D. PROCEDURE
  1. Obtain five 30 cm strips of presoaked dialysis tubing.
  2. Tie a knot in one end of each piece of dialysis tubing with a small piece of yarn to form 5 bags.
  3. Pour 20 mL of each of the following solutions into separate bags:
  A. Distilled water
  B. 0.2 M sucrose
  C. 0.4 M sucrose
  D. 0.6 M sucrose
  E. 0.8 M sucrose
  4. Remove air from each bag by drawing the dialysis bag between two fingers. Tie off the other end of the bag. Make sure to leave sufficient space for expansion of the contents in the bag.
  5. Rinse each bag gently with tap water to remove any sucrose solution spilled during the filling.
  6. Carefully blot the outside of each bag, find and record the initial mass of each bag.
  7. Place each bag in an empty cup, and label the cup to indicate the molarity of the solution in the dialysis bag.... [continues]

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