# By Don Nguyen, Erik Wislinsky, Clint Beckner, Ryan Brophy, and Jason West.

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By Don Nguyen, Erik Wislinsky, Clint Beckner, Ryan Brophy, and Jason West

 The purpose of this experiment is to test if the molarity of different NaCl(aq) solutions effect the rate of osmosis in a potato core.  We will be testing.5% salt, 1%, 2%, and 4%

 If osmosis flows from an hypotonic environment to a hypertonic environment and we place potato cores in different percents of salt solutions, then the potato core in high % salt solutions will loss weight and potato cores in low % will gain weight. There is a certain molarity where the potato is at equilibrium and will be isotonic with respect to the solution.

 Get five beakers with a 100mL line  Label each beaker (1-5)  Fill each beaker with 50mL of distilled water(dH 2 O)  Add.5 grams of salt to beaker 2  Add 1 gram of salt to beaker 3  Add 2 grams of salt to beaker 4  Add 4 grams of salt to beaker 5  Fill each beaker with more distilled water until the water line is at the 100mL mark  Stir with scupula  Get a potato

 Use a coring tool to get five pieces of potato  Cut each piece to weigh.06 grams (g)  Put one piece of potato in each beaker  Let osmosis do its thing for 30 minutes  When 30 minutes has past, remove each piece of potato  Gently dry each piece on a paper towel (make sure not to squeeze water out of the potato and only remove excess water from the outside)  Once again, weigh each piece of potato  Subtract weight before soak from weight after soak for each piece  If the difference is positive, the potato lost water and if the difference is negative, the potato gained water

Concentration (Molarity) Weight of Potato Before Weight AfterChange in Mass (g) 00.60.80.2g 0.05020.60.70.1g 0.10040.6 0g 0.20080.60.5-0.1g 0.40160.60.5-0.1g

 Conclusion: How does this lab relate to what you are studying?  Purpose  (restate purpose in past tense, including percent salts used.)  Observations  At.1004 M salt solution, the potato was at in an isotonic environment. With molarities higher than that, the potato was hypotonic with respect to the solution. And with molarities lower than.1004, the potato was hypertonic.  Hypothesis  Our hypothesis was correct. We found the values at which the potato was hypertonic and hypotonic. We even found the molarity of salt at which the potato was isotonic (1.004).  If you look at our data, you can tell that it agrees with our hypothesis because we have values on both sides representing hypo/hypertonic environments of salt.  Error  Things that could have possibly gone wrong with our experiment would include: faulty equipment, reading data improperly, perfection and contamination of solution/solute, human error, un-constant temperature, and lack of a perfect external environment.

 Things we could have changed to improve this experiment would include:  More increments of molarities of NaCl  More exact measurements  Longer time in hypo/hypertonic environments  More exact equipment to make measurements  Have robots do it so as to eliminate human error  If we could have EVERYTHING for this experiment, we could make it perfect by:  Doing the experiment in a vacuum  Using infinitesimally small and exact measurements  And again, have robots do it for us   What we learned:  We learned that when a potato is in a hypotonic solution it will gain weight through osmosis. The potato will lose weight if we put it in a hypertonic environment. And it will stay at equilibrium if it is in an isotonic environment.  We learned that we can see osmosis through the weight of potatoes after being in different salt solutions.  Osmosis is the diffusion of H2O across a cell membrane  After further research we found that cells sometimes use facilitated diffusion to equalize themselves by pumping water in or out. Aquaporins make this possible. Aquaporins are proteins in the cell membrane that pump water. They essentially do the job of a plumbing system. So this way, cells can quickly move water instead of just letting it slowly leak through the membrane. So these water channels increase membrane permeability to water.

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