SHS Lacrosse Monster #2
Dates performed:
10/10/11 and 10/11/11
Introduction:
The purpose of the laboratory investigation was to observe the diffusion of water across a semi-permeable membrane. In this lab, dialysis tubing was used to represent the semi-permeable cell membrane. Three dialysis tubes were prepared with 5% sucrose solution and were soaked in solutions of different concentrations. The diffusion of water across a semi-permeable membrane is called osmosis. When water diffuses, the water molecules move from a hypotonic environment to a hypertonic environment. Hypotonic means less concentrated than another solution. Hypertonic means more concentrated than another solution. If two solutions have equal concentration, they are said to be istonic
Hypothesis:
If three 8 in. sections of dialysis tubing are filled with a 5% sucrose solution, carefully weighed, and then one is placed in water, a second is placed in a 5% sucrose solution, and the third is placed in a 15% sucrose solution, then the tube in water will gain mass, the tube in 5% sucrose solution will stay the same mass, and the tube in 15% sucrose solution will lose mass.
Materials
Water
5% sucrose solution
10% sucrose solution
15% sucrose solution
Three Styrofoam cups
Erlenmeyer flask
Pipettes
Electronic balance
Weighting boat
Dialysis tubing (1 inch wide)
String
Scissors
Paper towels
Methods:
1. That dialysis tubing was cut into 8 inch sections and soaked in water.
2. Three sections of the tubing were removed from the water.
3. One end of each section was tied tightly with string.
4. Using a pipette, all three tubes were filled with approximately 5 mL of 5% sucrose solution.
5. The other ends of all three tubes were then tied tightly with string. The long ends of the string were cut with scissors.
6. Using masking tape. One of the Styrofoam cups was labeled as “water”. A second Styrofoam cup was labeled “5% sucrose”. The Styrofoam cup