Transcript Does Molarity of NACL(aq) effect the rate of osmosis?

By Don Nguyen, Erik Wislinsky, Clint
Beckner, Ryan Brophy, and Jason West
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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%
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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.
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Get five beakers with a 100mL line
Label each beaker (1-5)
Fill each beaker with 50mL of distilled water(dH2O)
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
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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 After
Change in Mass
(g)
0
0.6
0.8
0.2g
0.0502
0.6
0.7
0.1g
0.1004
0.6
0.6
0g
0.2008
0.6
0.5
-0.1g
0.4016
0.6
0.5
-0.1g
0.25
0.20
Change in Mass (Grams)
0.15
0.10
0.05
0.00
0
0.0502
0.1004
-0.05
-0.10
-0.15
Molarity (M)
0.2008
0.4016
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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.
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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
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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.