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Solute Concentration of Potatoes Lab #1

Purpose: To find the molarity/concentration of potato cytoplasm.

Materials: As on page 1 in the lab handout.

Procedure: As on page 1 in the lab handout.

Data and Observations:
Test Tube #| Concentration of sucrose solution (mol/L)| Initial Mass (g)| Final Mass| Percentage change in mass| 1| 1.0 mol/L| 3.00g| 2.25g| -25.0%|
2| 0.9 mol/L| 2.70g| 2.07g| -23.3%|
3| 0.8 mol/L| 2.92g| 2.25g| -22.9%|
4| 0.7 mol/L| 2.60g| 1.94g| -25.4%|
5| 0.6 mol/L| 2.61g| 2.04g| -21.8%|
6| 0.5 mol/L| 2.68g| 2.21g| -17.5%|
7| 0.4 mol/L| 2.57g| 2.26g| -12.1%|
8| 0.3 mol/L| 2.63g| 2.70g| 2.70%|
9| 0.2 mol/L| 2.77g| 3.17g| 14.4%|
10| 0.1 mol/L| 3.10g| 3.55g| 14.5%|
11| 0.0 mol/L| 2.91g| 3.61g| 24.0%|

Discussion:

1. Some potatoes increased in mass while others decreased due to osmosis. Potatoes that had a higher concentration increased in mass because water passed through the membrane into the potato in an effort to dilute it. Potatoes that had a lower concentration than the solution decreased in mass because water flowed through the membrane into the solution trying to dilute the solution. The water moves to the higher concentration to dilute it/maintain homeostasis, increasing or decreasing mass depending on whether it goes in or out. 2. According to the graphed data (attached) gathered from this lab, the approximate concentration at which the solution and potato cytoplasm is isotonic is 0.4 mol/L. I can therefore conclude that the approximate solute concentration of potato cytoplasm is also 0.4 mol/L. This is because the concentration of potato cytoplasm never changed throughout the experiment, but the sucrose solution did. Seeing as isotonic means both concentrations are equal, I can conclude that the potato cytoplasm was always around 0.4 mol/L. 3. I suspect that the mass of the potato would decrease just as it did with the sucrose...
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