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Kristina Gjoshevska
19-Sep-16

LAB REPORT: OSMOSIS AND DIFFUSION
● Analysis of the effects of aqueous sucrose solutions with different molarities on the
mass of potato cubes
...

Osmosis is the process by which molecules of a solvent pass from a less concentrated
solution to a more concentrated, to equalize the concentrations of both solutions
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Both osmosis
and diffusion are active transport of ions or molecules across a cell membrane, which
means that energy is required for both of these processes
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● Materials:
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sucrose
distilled water
potatoes
knives
beakers
spoons
forceps
mass scale
graduated cylinder
thermometer
paper towels

● Procedure: first, we calculated the mass of sucrose we need to add in 100ml of distilled
water to create solutions with different molarities
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2M that was 6
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4M it
was 13
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6M it was 20
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8M it was 27
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23 grams
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After that, we
used a graduated cylinder to measure 100ml distilled water for each beaker and mixed it
with spoons until the sugar completely dissolved in the water
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The room temperature
was 27 degrees Celsius
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Initial Final
Molarity Mass Mass

Mass
%
Difference change
in mass
0
...
2%

Distilled 5
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2M
5
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53g -0
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3%

0
...
9g

4
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19g

-3
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6M

5
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72g -0
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2%

0
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9g

4
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5g

-10
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9g

4
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64g

-13%

● Calculations:
- 0
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846g sucrose
- 0
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846g = 13
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6M = 3*6
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538g
- 0
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846g = 27
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0M = 5*6
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23g

- 6g - 5
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3g; (0
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7)100 = 5
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53g - 5
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07g; (-0
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6)100 = -1
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71 - 4
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19g; (-0
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9)100 = -3
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72g - 5
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48g; (-0
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2)100 = -9
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40g - 4
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5g; (-0
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9)100 = -10
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26g - 4
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64g; (0
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9)100 = -13%

Water potential calculation: Ψ = Ψp + Ψs
Ψs = -iCRT (i = ionization constant which is 1 for sucrose because it does not ionize in
water, C = molar sucrose concentration at equilibrium, R = pressure constant, handbook
value of 0
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)
Ψs= -1 * 0
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0831 * 300 = -4
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When the potato cube was submerged in the distilled water, the water
particles entered through the semi permeable cell membranes of the potato cells to
equalize the concentration
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However, when there was sucrose in the water the
particles moved from the potato towards the solution, and the more sucrose was present,
the more the potatoes shrunk because it took more particles to reach equilibrium

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