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Osmosis

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Submitted By shannen21
Words 499
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Demonstration of Osmosis using visking tubing

Aim
The aim of the experiment is to demonstrate the effects of osmosis using visking tubing, warm water and sucrose solution.
Method

Test tube A on the inside is hypertonic because there is a more concentrated solute, on the outside it is hypotonic because there is a less concentrated solute.
Test tube B is isotonic both on the inside and outside.
Test tube C on the inside is hypertonic and on the outside is hypertonic.

Experiment

During the experiment 3 test tubes were placed in a wire rack, the test tubes were then labelled A, B and C.
Tube A was half filled with 0.1M sucrose solution whilst tube B was half filled with 0.5M sucrose solution, tube C was half filled with 1.0M sucrose solution.
Three lengths of visking tubing were soaked in warm water for two minutes. One piece of visking tubing was three quarters filled with 0.5M sucrose solution and knotted at either side, it was then rinsed to get rid of any sucrose solution on the outer tubing. The visking tubing was then dried and weighed. The same was done with test tube B and C.
After 10 minutes the cell models (visking tubing) were removed from the test tubes and dried and weighed. The results were recorded and the cell models were returned to the test tubes. After 20 and 30 minutes the same thing was done and results were recorded afterwards. Tube | Start | 10 Minutes | 20 Minutes | 30 Minutes | A | 19.16g | 18.29g | 19.81g | 20.13g | B | 14.81g | 14.15g | 14.74g | 14.82g | C | 16.15g | 15.58g | 15.02g | 14.67g |

Conclusion
Cell model A was found to gain mass through osmosis because water has passed through higher water concentration which is a hypotonic solution to a lower water concentration which is a hypertonic solution.
Cell model B never gained or lost any water concentration because the solutions inside and outside are the same which means it is isotonic.
Cell model C lost mass through osmosis because water passed out from its hypotonic interior to its hypertonic exterior.
The process is called osmosis, during this water molecules move down a water concentration gradient from high to low water concentration through a selectively permeable membrane.

Evaluation of experimental procedure

The results could be invalid if he cell models weren’t rinsed at the start of the experiment because there could be excess sucrose solution on the outside of the cell models adding weight and making the cell model heavier.
Results could also be invalid if cell models weren’t dried properly because there could also be excess solution on the outside making the cell model heavier.
The reliability of the experiment could be checked by repeating the experiment and comparing results and also checking that each of all the cell models are rinsed and dried and that all of the test tubes have the correct amount of solution in them.

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