Diffusion and Osmosis Lab

In this lab we will investigate the processes of diffusion and osmosis in a model membrane system

Objectives:

• We will understand the mechanisms of diffusion and osmosis and their importance to cells
• The effects of solute size and concentration gradients on diffusion across selectively permeable membranes
• The effects of a selectively permeable membrane on diffusion and osmosis between two solutions separated by the membrane
• Describe the effects of water gain or loss in animal and plant cells

Data:

Table 1.1 Starch

	Initial Content	Solution Color		Starch Present
		Initial	Final	Initial	Final
Bag	15% Glucose; 1% starch
Beaker	Water and IKI

Analysis of Results:

1. Which substance(s) are entering the bag and which are leaving the bag?
2. Explain the results you obtained. You may use the size of the following molecules to help: water molecules, IKI molecules, membrane pores, starch molecules.

Table 1.2: Dialysis Bag Results

Contents in Dialysis Bag	Initial Mass	Final Mass	Mass Difference	Percent Change in Mass
0.0 M Distilled Water
0.2 M Sucrose
0.4 M Sucrose
0.6 M Sucrose
0.8 M Sucrose
1 M Sucrose

Use the following equation to calculate Percent Change in Mass

Final Mass – Initial Mass

Percent Change in mass = ------------------------------ X 100

Initial Mass

Analysis of Results

3. The independent variable is _____________________; the dependent variable is __________________
4. Explain the relationship between the change in mass and the molarity of sucrose within the dialysis bags.
5. Predict what would happen to the mass of each bag in this experiment if all the bags were placed in a 0.4 M sucrose solution instead of distilled water. Explain your response. (Hint: not all bags will do the same thing)

Diffusion and Osmosis Lab

In this lab we will investigate the processes of diffusion and osmosis in a model membrane system

Objectives:

• We will understand the mechanisms of diffusion and osmosis and their importance to cells
• The effects of solute size and concentration gradients on diffusion across selectively permeable membranes
• The effects of a selectively permeable membrane on diffusion and osmosis between two solutions separated by the membrane
• Describe the effects of water gain or loss in animal and plant cells

Data:

Table 1.1 Starch

	Initial Content	Solution Color		Starch Present
		Initial	Final	Initial	Final
Bag	15% Glucose; 1% starch
Beaker	Water and IKI

Analysis of Results:

1. Which substance(s) are entering the bag and which are leaving the bag?
2. Explain the results you obtained. You may use the size of the following molecules to help: water molecules, IKI molecules, membrane pores, starch molecules.

Table 1.2: Dialysis Bag Results

Contents in Dialysis Bag	Initial Mass	Final Mass	Mass Difference	Percent Change in Mass
0.0 M Distilled Water
0.2 M Sucrose
0.4 M Sucrose
0.6 M Sucrose
0.8 M Sucrose
1 M Sucrose

Use the following equation to calculate Percent Change in Mass

Final Mass – Initial Mass

Percent Change in mass = ------------------------------ X 100

Initial Mass

Analysis of Results

3. The independent variable is _____________________; the dependent variable is __________________
4. Explain the relationship between the change in mass and the molarity of sucrose within the dialysis bags.
5. Predict what would happen to the mass of each bag in this experiment if all the bags were placed in a 0.4 M sucrose solution instead of distilled water. Explain your response. (Hint: not all bags will do the same thing)