Raisha Miggins Lab5Osmosis

Raisha Miggins
Lab 5: Osmosis

Purpose
The purpose of this lab was to explore the concept of Osmosis using dialysis tubing and different concentrations of sucrose solutions, and to help one better understand what happens to cells when they are exposed to solutions of differing tonicities.
Hypothesis
If the four dialysis tubes containing different concentrations of sucrose are all placed in their appropriate solutions for 20 minutes, then my predictions are as follows: The 1% in 1% sugar solution will keep a constant weight and stay the same size. The 1% in 50% solution will shrink, due to the higher concentration of sugar outside of the bag. The 20% in 1% solution will swell, due to the higher concentration inside of the bag, and the 50% in 1% solution will do the same.
Materials and Methods Materials
The materials used in this experiment were a scale, 24" of dialysis tubing, 4 transfer pipettes, sugar, scissors, rubber bands, four coffee cups, a 250ml graduated cylinder, a ruler, a small sauce pan, and 3 clean containers.

Methods
To begin this experiment, four 6-inch pieces of dialysis tubing were cut and soaked in a coffee cup filled with tap water for 2 hours. While waiting, the three following sugar solutions were prepared:
For solution A, the 1% sugar solution, 5 grams of sugar were added to a 250ml graduated cylinder and then tap water was added up to the 250ml mark. A small piece of plastic wrap was placed over the top of the graduated cylinder and the solution was mixed. Next, the contents were poured into a small saucepan over the stove. The graduated cylinder was then filled with 250 more milliliters of water, and then poured into the saucepan as well. The mixture was then heated on the stove and stirred until the sugar was dissolved. Once this happened, the solution was removed from the saucepan, poured into a container, and labeled as 1% sugar solution.

Next, 100 grams of sugar was added to a 250ml graduated cylinder, and then water was added up to the 250ml mark. A small piece of plastic wrap over the top of the graduated cylinder, and the solution was mixed. The contents were then poured into a small saucepan over the stove. Next, the graduated cylinder was then filled with 250 more milliliters of water, and then poured into the saucepan as well. The mixture was then heated on the stove and stirred until the sugar was dissolved. Once this happened, the solution was removed from the saucepan, poured into a container, and labeled as 20% sugar solution.

Finally, 250 grams of sugar was added to a 250ml graduated cylinder, and then water was added up to the 250ml mark. A small piece of plastic wrap over the top of the graduated cylinder, and the solution was mixed. The contents were then poured into a small saucepan over the stove. Next, the graduated cylinder was then filled with 250 more milliliters of water, and then poured into the saucepan as well. The mixture was then heated on the stove and stirred until the sugar was dissolved. Once this happened, the solution was removed from the saucepan, poured into a container, and labeled as 50% sugar solution.

After the third solution was heated, the simulated cells were ready to be made. One end of each of the dialysis tubings were folded and wrapped tightly with a rubber band to seal the “cells”. Next, each tube was opened (from the other end) and filled the to the ¾ mark with one of the solutions previously mixed. The other end of the tubes was then sealed with another rubber band. Each tube was then weighed using a scale and placed into a coffee cup containing one of the four solutions (A- D). Each weight was then recorded into the table below. Each tube was soaked for 20 minutes, then removed from its solution for observations to be made. The tubes were then re-weighed, and the ending weights were also recorded into the table below. The following four conditions were set up:
A) The 1% sugar solution inside simulated cell 1 was placed in a coffee cup that also contained 1% sugar solution.
B) The 1% sugar solution inside simulated cell 2 was placed in a coffee cup that contained 50% sugar solution.
C) The 50% sugar solution inside simulated cell 3 was placed in a coffee cup that contained 1% sugar solution.
D) The 20% sugar solution inside simulated cell 4 was placed in a coffee cup that contained 1% sugar solution also

Results

Table 1- The Movement of Sugar Across a Semi- Permeable Membrane

In this table one will find the initial weight of each bag before they were placed into their appropriate solutions, as well as the final weight. The tonicity of each of the solutions are also included in the table, which helps further explain why the “cells” behaved in such a way.

Contents:
% sugar solution within bag (simulated cell)/ % sugar solution in the beaker:
Initial weight (include units):
Final weight, weight after 20 min (include units):
Change in weight (include units):
Environment your simulated cell was placed in:
1%/ 1% 10g 10.1g
+ .1g Isotonic
1%/ 50% 9.9 g
5.4g
- 5.4g Hypotonic
50%/ 1% 10.3g 15.9g +5.6g Hypertonic
20%/ 1% 10.9g 14.1g +3.2g Hypertonic

Conclusion

My hypothesis was fully supported. I previously predicted that the 1% in 1% sugar solution would keep a constant weight and stay the same size, the 1% in 50% solution would shrink due to the higher concentration of sugar outside of the bag, the 20% in 1% solution would swell due to the higher concentration inside of the bag, and the 50% in 1% solution would do the same. After the bags were observed and re-weighed, each of my predictions were proven to be true.