An Experiment To Determine The Water Potential Of Sweet Potato & Baking Potato

        Scales

        Ruler

Method

1. Use the cork borer to cut out 11 cylinders of sweet potato.
2. Cut each cylinder to 5cm lengths.
3. Wash each cylinder for 1 min
4. Dry cylinders, weigh and record results
5. Label the boiling tubes A-K Respectively
6. Put 10cm of the sucrose solution at different concentrations ranging from Distilled water to 1.8mol solution. Record which tube holds which concentration.
7. Put the cylinders in the boiling tubes.
8. Leave the test tubes for three hours to allow osmosis to occur
9. Remove cylinders from solution re-weigh and record results.

Results

Conclusion

        This experiment shows the sweet potato absorbs water at from a solution with a higher concentration of sugar present as oppose to the baking potato which stops absorbing water when the solution became 0.2 molar. This shows there is a higher concentration of sugar in sweet potato than in baking potatoes because the only moves along a gradient where one concentration is higher on one side. For example if the sweet potato had a sugar concentration of 0.9 and was put in a 0.3 molar sugar solution it would absorb it would absorb water by osmosis. In a concentration of sugar which is higher than that which is present in the sweet potato the water would be taken out of the potato thus reducing the weight.

From this experiment it was gathered that the sweet potato had a sugar concentration of 0.61 molar solution whereas the baking potato has a 0.33 molar sugar solution present. This is probably why the sweet potato gained the name “sweet” as its sugar content is almost twice as much as the baking potato

Evaluation

        There were not many areas in which this experiment could be improved because there weren’t many variables to control. The only things which may have affected the results were the varied weights of the cylinders of potato if they were all weighed out to the same weight they would all have the same surface area so there would be the same area for the water to diffuse across. The temperature should have also been recorded and kept constant throughout the experiment because if the temperature increases the water will diffuse faster at higher temperatures.

        In the last result for the baked potato where the weight went up again was because the cylinder was not dried properly and the solution when at that concentration was very viscous so it stuck to the outer layer of the cylinder thus increasing the weight.