Transcript Effect of Concentration on Osmosis

By: Michael Roberts
Josh Kolbenschlag
Brady James
Taylor Rice
EFFECT OF CONCENTRATION ON OSMOSIS
PROCEDURE
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Step 1: Gather Materials:
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5 200 mL cups labeled 0%, 1%, 2%, 3%, 11%
Triple Beam Balance
Iodized NaCl or table salt
5 cylindrical shaped potatoes of all same size and mass
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Step 2: Make Concentrated Solutions
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Fill a graduated cylinder with approximately 50mL of deionized
water
Add the correct mass of iodized NaCl (table salt) based on
percentages 0, 1, 2, 3, 11, to the water in the graduated cylinder
and stir thoroughly.
Add deionized water till the graduated cylinder until it reaches
100mL
Pour the solution into the correct labeled cups
Step 3: Make Identical Potato Slices
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Extract 5 cylinder shaped potato using a 5mm diameter hollow tool
Place cylinder on triple beam balance and record the mass of each.
Cut the cylindrically shaped potatoes until they are of equal mass.
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Step 4: Place Potatoes into the Cups with
Concentrated Solutions of Iodized NaCl
 Place
5 cylindrically shaped potatoes into the 5
different concentrated solutions.
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Step 5: Wait 30 min.
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Step 6: Weigh the potatoes.
 Take
the potatoes out of the solutions and completely
dry them off.
 Mass them on the triple beam balance and record
the final mass.
PURPOSE AND HYPOTHESIS
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Purpose:
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Hypothesis:
The purpose of our experiment was to not only
find the correct isotonic solution at which osmosis is at
equilibrium, but to study the effects of different concentrated
solutions of iodinized NaCl.
Our Hypothosis was that the different
concentrations of NaCl would affect the rate of osmosis in
different ways. We knew that the higher concentrated the solution
the more rapid diffusion of water would leave the potato cores, as
well as the opposite, with the lower concetrations of solution
water would diffuse into the potato cores causing them to gain
weight. Our prediction on the correct isotonic solution was that at
2% the potato would be at equilibrium with the sourounding
iodinized NaCl solution.
DATA:
Solution:
0%
1%
2%
3%
11%
Mass of
Potato
(Initial)
2.1 grams
2.1 grams
2.1 grams
2.1 grams
2.1 grams
Mass of
Potato
(Final)
2.2 grams
2.1 grams
2.0 grams
1.9 grams
1.7 grams
Difference
of Mass:
0.1 grams
0 grams
-0.1 grams
-0.2 grams
-0.4 grams
GRAPH:
Effects of Concentration of Osmosis
0.2
0.1
y = -0.0409x + 0.0192
R² = 0.874
Change in Mass (grams)
0
0
2
4
6
8
10
12
Series1
-0.1
Linear (Series1)
Linear (Series1)
-0.2
-0.3
-0.4
-0.5
Percent Concentration by Mass
GRAPH ANALYSIS
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Based on the linear regression line from our
experiment, it is possible to make the conclusion
that the salt concentration of the potato equals
approximately 0.5% by mass. This equals the
isotonic concentration of a solution to where the
mass of the potato would not change if it was
placed in that solution. There is a degree of error
to our experiment because the linear regression
line has a r^2 value of .874, which would skew this
isotonic concentration value we calculated.
VARIABLES
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Constant variables in Experiment:
Salt (iodized NaCl)
 Size, mass, and type of potato
 Deionized water
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Changing Variables in Experiment:

Concentration of salt
CONCLUSION
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Osmosis is defined as: Diffusion of fluid through a semipermeable
membrane from a solution with a low solute concentration to a solution with
a higher solute concentration until there is an equal concentration of fluid on
both sides of the membrane.
In this lab we studied the effects of concentrations of iodinized NaCl and
their inverse relationship of the affect of the rate of change of osmosis. We
concluded that the potato had approxomitely .5% NaCl concentration by
mass and the isotonic solution would be roughly the same. The affects of
different concentrations was rather suddle and at higher concentrations
water diffused out of the potato and at lower concentrations into the potato.
Our hypothosis mirrored this with the exception that at 2% the solution was
not isotonic.