The Effect of Solute Concentration on Osmosis in Potatoes. Essay

935 Words May 16th, 2011 4 Pages
Martina Oganesyan
Title of investigation: The effect of solute concentration on osmosis in potatoes.
Research question: What is the solute concentration of a potato?
Hypothesis:
Osmosis is the movement of water across the membrane from an area of high concentration to an area of low concentration. The osmosis continues until the solute concentrations are equal in both areas. In this experiment, we put pieces of potatoes into test tubes with sugar solutions of different concentrations and leave them there over night. It was done in order to compare the initial mass of the pieces and the ones after being placed into the solute concentration. Pieces which were placed into a hypotonic (lower) concentration of solute should increase in mass
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Place cellophane over each test tube in order to prevent water from evaporating and leave them standing for night. Take the potatoes out of the solutions the next day and record their mass.
Results:
The massic percentage is found using the formula:

Concentration (mol/l)± 1.9x10-4 | Initial mass ± 0.05 | Final mass± 0.05 | Massic % | Error (%) |
0.1 | 2.30 | 3.02 | 23.84 | 1.307722964 |
0.2 | 4.37 | 5.30 | 17.55 | 0.531847209 |
0.3 | 3.51 | 3.94 | 10.91 | 0.432463495 |
0.4 | 1.93 | 2.13 | 9.39 | 0.684085376 |
0.5 | 2.52 | 2.46 | -2.44 | 0.147540674 |
0.6 | 3.25 | 3.06 | -6.21 | 0.298438799 |
0.7 | 3.05 | 2.53 | -20.55 | 1.149326081 |
0.8 | 3.5 | 2.73 | -28.21 | 1.436085282 |
0.9 | 3.2 | 2.4 | -33.33 | 1.909722222 |
1.0 | 2.95 | 2.33 | -26.61 | 1.593043632 |

Evaluation:
As we can see above, there are two charts: Massic percentages and concentration of the solutions; Molar concentrations and % increase in length. The second chart shows the results of another group, who used the same method but recorded change in length rather than change in mass.
Using the equation y=-66.631x+31.081 we can find the solute concentration of the potato: as it is the x value for when y=0, we solve the equation:

0=-66.631x+31.081

We find x=0.47 so according to our experimental data the solute concentration of the potato was 0.47 mol/l.
The correlation coefficient is R2=0.95 which is very good, whereas for…

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