Method
- A piece of A4 paper was marked with the letters A, B and C.
- One half of a Petri dish was placed on each of the labels making sure that the Petri dishes were all the same size.
- Placing a potato on a white tile to protect the table a cork borer was used to make 9 cylinders.
- Using the ruler and scalpel the cylinders were cut to an equal length. In this case each cylinder was cut to 6.5cm in length ensuring that there was no skin left on the ends of the potato, as this could affect the results of the experiment.
- Three cylinders of potato were placed in each of the Petri dishes.
- The solutions labelled A, B and C was poured into the corresponding Petri dishes making sure that there was an equal amount in each.
- The experiment was left for a specified time and then the potato was dried and measured again and the results noted.
Diagram
Results
The results were as follows:
Conclusion
Solution A:
The potato cylinders in solution A. all decreased in size by 6.7%.
The water has left the potato which made is soft and limp which is known as being plasmolysed meaning that all of the water had left the potato and diffused in to the solution in the Petri dish. This shows that the liquid in the Petri dish had a higher concentration of sugar than the concentration of sugar in the potato.
This indicated that the potato cylinders were sitting in a concentrated sugar solution thus proving the following:
OSMOSIS IS THE DIFFUSION OF WATER MOLECULES ACROSS A SEMI-PERMEABLE MEMBRANE FROM A REGION OF HIGH WATER MOLECULE CONCENTRATION TO A REGION OF LOW WATER MOLECULE CONCENTRATION.
Solution B:
The potato in solution B only changed by 1.5%.
This shows that the same amount of water had left and entered the cells of the potato. This shows that the concentration of sugar in the water was the same as the concentration in the potato. This means the solution in the Petri dish was a dilute solution.
Solution C:
The potato in solution C increased in size by an average of 3.1%.
This shows that the potato took water until it could not take in any more and became turgid meaning that it was rigid and hard. This means that the concentration of water in solution C was higher than the concentration of water in the potato.
