Test on osmosis and its effect on pieces of potato

*~Hypothesis:

Taking the theory into consideration, I hypothesise that the potato chips left in any concentration of salt solution, would decrease in length and weight (flaccid), as osmosis would make the water flow from the potato to the surrounding hypertonic solution as the net movement of molecules is from a higher concentration to a lower one, and in this case the water inside the potato would be more.

   Whereas in distilled water the level of water molecules outside the cell would be relatively greater and the water would flow from outside the cell, to the inside, down a concentration gradient, making the cell increase in length and weight (turgid)

*~Variables:

Constant=time

Dependent=length and weight

Independent=concentration of solution

*~Safe test:

As this test does not have any dangerous elements involved, there aren’t any necessary precautions that need to be taken except handling the fragile apparatus with extreme caution, so that it does not break.

*~Fair test:

In order to make this a fair experiment, few things must be kept in mind:

-The beakers should be kept in the same environment and temperature throughout.

-The top pan balance should be brought to zero before conducting the weighing.

-We should be careful not to perform parallax errors while taking each potato chip’s measurement.

*~Apparatus:  

 .                    1. 4 pieces of raw potato

                      2. Cork borer- used to extract pieces of potato,

                      3. 4 beakers

                  4. Marker

                      5. Salt solution of 0.1 moles

                      6. Salt solution of 0.3 moles

                      7. Salt solution of 0.5 moles

                      8. Distilled water

                      9. Top pan balance

                    10. Ruler

                   

Procedure:

1. Using the cork borer, carefully extract 4 pieces of potato from the single raw potato. Apply force on the cork borer, in order to get a fine, cylindrical shape.
2. Pour each of the solutions in different beakers.
3. Label each of the beakers, according to the level of molarity(or distilled water), with the marker.
4. Measure the length of each potato chip, using the ruler, and record the readings.
5. Weigh each of these chips, using the top pan balance, and record the readings.
6. Place each of the chips in the respective beakers, filled with different concentrations of salt solution.
7. Label accurately the length and weight of the potato that has been placed in the particular concentration of salt solution, on the beaker, using a marker.
8. Leave the experiment as it is, till a period of 1 day, under the same conditions.
9. After a day, remove the potatoes, using a tong, one by one, out of each beaker.
10. Re-measure and re-weigh each piece and record the new results.
11. Calculate the percentage change in weight and length.

 

Observations:

   

Conclusion:

 On a concluding note, the experiment was successful in showing the varying effects of osmosis for cells kept in different levels of morality. The observations from the execution of the experiment showed that the cell in question (potato chip), decreases in length and weight, when put in hypertonic solutions of salt, as the water flows out from the cell into the surrounding substance, making it flaccid and thus decreasing the length and weight.

    E.g. Chip kept in 0.1 mole solution: decreased in length by 7.1%, and in weight by 5.1%

          Chip kept in 0.3 mole solution: decreased in length by 6.66% and in weight by 5.2%

          Chip kept in 0.5 mole solution: decreased in length by 11.1% and in weight by 13.5%

     

           The observations also showed that the potato chip increases in length and weight when put in distilled water as the outside of the cell has larger water potential and therefore the movement of water molecules would be from outside the cell to inside the cell, thereby increasing the length and weight.

E.g. Chip kept in distilled water: increased in length by 6.66% and in weight by 12.6%

Error analysis:

There wasn’t really any scope for errors in the experiment as by far, all precautions were taken to ensure it being a fair test, without any unnecessary safety hazards.

• But it is possible that some of the potato could have gotten extremely soggy and broken off into the water, leaving behind the chunk of potato. This would have been difficult to notice; therefore it is not a proved, but possible error.
• As everything that would ensure a fair test was taken care of, there weren’t any other noticeable or intentional errors.
• It is possible that the solution was not accurately concentrated according to the said no. of moles.
• The potato could have disintegrated into the water.
• The weight of the potatoes weren’t very accurate as while weighing it, the breeze etc. could have altered the results.

Improvements:

As the experiment followed strict guidelines, there wasn’t any scope for improvement either. But the implementation of one aspect could have made test easier, and could have shown the results in a more comparative basis.

- The potato chips should have been cut in equal lengths, therefore not only making the test easier, but the comparing of the decrease and increase would have been better and the results would have been more impressive, and more comprehensive.