Cell Transportation Lab: Osmosis
Introduction and Hypothesis
If the soda has more sweetener, more water molecules will exit the tube. If distilled water has fewer solutes, water molecules will enter the tube.
Osmosis is the tendency of water to pass through a semipermeable membrane into a solution where the solvent concentration is higher, thus equalizing the concentrations of the materials on both sides.The purpose of this investigation was to help us understand the process from a visual perspective. The control variables were the amounts of water in each tube, size of the cups, the amount of the solution, and type of tube. Then, the independent variable was each solution, while the dependent variable was the mass of the tube.
Three dialysis tubes
200 mL of each of the three various solutions
20 mL of drinking water
Tie one end of the dialysis tube
Place funnel at opposite end of the tied section
Pour 20 mL of drinking water into the tube
Repeat step 2 on the other end
Repeat steps 2-5 on two more tubes
Measure and record the mass of each tube into a data table
Pour 200 mL of a solution into three cups (different solution in each cup)
Place a dialysis tube into each solution
Wait 24 hours then remove and weigh the dialysis tubes
Record data and create conclusion
If the soda has more sweetener, more water molecules will exit the tube. If distilled water has fewer solutes, water molecules will enter the tube. The data regarding the soda is correct; more water molecules exited the tube during osmosis. However, the distilled water’s weight decreased as well. This could have been due to human error: not tying the tubes tightly enough with the string, and water could have leaked out due to that as opposed to osmosis. From the data, it is simple to conclude that osmosis causes weight to decrease in sodas and distilled water, although the distilled water dialysis tube is the anomaly- due to human error, it did not work correctly.