Lab 5: Osmosis

Purpose: The purpose of this lab is to familiarize you with osmosis and, specifically, what happens to cells when they are exposed to solutions of differing tonicities.

Hypothesis: If we add higher concentrations of sugar to the dialysis tubing, then the net movement of coffee into the dialysis tubing will increase.

Materials scale or balance
24" dialysis tubing
4 transfer pipets sugar scissors rubber bands four coffee cups - they need to be roughly the same size
250ml graduated cylinder ruler small sauce pan
3 clean containers (600mls (about 20 ozs) or larger)

Procedure:

1. Cut four 6-inch pieces of dialysis tubing and soak in a coffee cup filled with tap water for 2 hours prior to your start
You will record this as the initial weight in table 1.

4. You will set up the following four conditions:
A) Place 1% sugar solution inside simulated cell 1 using your transfer pipets, and place that cell in a coffee cup that also contains 1% sugar solution.
B) Place 1% sugar solution inside simulated cell 2 using your transfer pipets, and place that cell in a coffee cup that contains 50% sugar solution.
C) Place 50% sugar solution inside simulated cell 3 using your transfer pipets, and place that cell in a coffee cup that contains 1% sugar solution.
D) Place 20% sugar solution inside simulated cell 4 using your transfer pipets, and place that cell in a coffee cup that contains 1% sugar solution.
5. Wait 20 minutes. While you are waiting, produce a hypothesis, or predict what will happen to the size of your bag (simulated cell) in each of the given environments, will the size increase, decrease, or stay roughly the same after 20 minutes. During this time, you can also record the tonicity of each environment your simulated cells were placed into, hypotonic, isotonic, or hypertonic. After 20 minutes, weigh your bags again. Record this data in table 1 as your final weight, determine the change in weight, and indicate the tonicity of each condition below in your table

Results:
Table 1:Osmosis Contents:
% sugar solution within bag (simulated cell)/ % sugar solution in the beaker: Initial weight