Directions Tie a piece of semipermeable membrane around the mouth of the thistle tube using a tight rubber band or string.
Dissolve a teaspoonful of sucrose in about 20 milliliters of water.
Invert the sealed thistle tube into a beaker containing water and hold it securely using a ring stand and clamp. You may have to use some tissue around the clamp to secure the tube tightly without breaking the glass.
Pour the sugar-water solution into the stem of the thistle tube so the level of the sugar water within is even with the level of the water in the beaker. Set this experiment aside until the next day.
Answer the following questions:
What do you observe after twenty-four hours?
What two molecules (molecular species) are involved in this experiment?
In which region was the concentration of water greater—inside or outside the thistle tube—when you first set up the experiment? Explain.
Based on what you have learned about membranes and osmosis, how could you explain the results of this experiment?