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# Osmosis Lab Report

In: Science

Submitted By xoxoccy
Words 732
Pages 3
Introduction
Water can diffuse across the partially permeable membrane of cells depending on the concentration difference between the inside and the outside of the cells. You are going to look at the effect of different concentrations of sugar solutions on potato cells. By measuring the mass of the potato cylinders, you will be able to find out if water has entered or left the potato cells.

Aim
To find out what happens to the mass of potato cells when they are left in increasingly concentrated solutions.

Hypothesis
My hypothesis was that if the concentration of sugar where the water potential is higher than the water potential of the potato, the mass of the potato will increase. On the other hand, if they have similar water potential, the mass will not change.

Variables
Independent variable: concentration of sugar
Dependent variable: change of mass of the potato before and after the experimant
Controlled variable: temperature

Apparatus
• Potato
• A 6mm Cork borer
• Ruler
• Scalpel
• White tile
• Sugar
• Distilled water
• Labelling pen
• 50mL measuring cylinder
• Weight balance
• Stopwatch
• Labels
• Paper towel
• 12 boiling tubes
• Boiling tubes rack
• Four 250mL beakers

Methods
1. Measure 100mL of distilled water into a 250mL beaker. Label it “0% sugar solution”.
2. Measure 100mL of distilled water into a third 250mL beaker. Add 20g of sugar into it and stir until fully dissolved. Label it “20% sugar solution”.
3. Measure 100mL of distilled water into a fourth 250mL beaker. Add 40g of sugar into it and stir until fully dissolved. Label it “40% sugar solution”. (Note that this solution might have already been prepared for you)
4. Extract 20mL of the “0% sugar solution” and add it to a boiling tube. Label the boiling tube with “0%”
5. Repeat step 5 two more times, so you will have 3 boiling tubes filled with “0% sugar solution”. It is also a good idea to label the boiling tube “1”, “2” and “3”.
6. Repeat step 5 and 6 for all of the solutions but label the boiling tubes appropriately.
7. Using a 6mm cork borer and a ruler, cut three potato cylinders that are each 4cm long.
8. Dry the potato cylinders with the paper towel and measure their masses.
9. Put one potato cylinder into each boiling tube for 30 minutes.
10. Take the potato cylinders out of the boiling tubes. Dry the potato cylinders with paper towel.
11. Record down their new masses.
12. Calculate the percentage change in mass in different sugar solutions.
13. Calculate the average values for the percentage change in mass in different sugar solutions.
14. Note down your results in a table.

Diagram

Results
Concentration of sugar solution (%)
B2oiling tube
Mass before (g)
Mass after (g)
Change in mass (%)
0
1
0.5g
0.52g
+0.02g
0
2
0.51g
0.51g
same
20
1
0.52g
0.473g
-0.047g
20
2
0.42g
0.411g
-0.009g
40
1
0.50g
0.323g
-0.177g
40
2
0.51g
0.313g
-0.197g

Conclusion
To conclude, I am able to see the effect of different concentration on the rate of osmosis through this experiment. The experiment was done by measuring the mass of potato before and after osmosis. And the result was that as the concentration increase, the rate of osmosis also increases, this tells that there is a decrease in mass. And it shows that my hypothesis was correct, “the concentration of sugar where the water potential is higher than the water potential of the potato, the mass of the potato will increase. On the other hand, if they have similar water potential, the mass will not change.”
According to the osmosis theory, if the concentration of the sucrose solution increase, the particles’ water potential will also increase, and will become higher than the particles that are in the potato.

Evaluation
During the experiment, there are some errors that cannot be able to control, such as the temperature of the room. This might slightly change the result yet make the experiment not a fair test. Another thing that would affect the experiment is that the sugar might not dissolve properly to the solution, and this might affect the rate of osmosis. If I have to do this investigation again, I would mix the solution better and to do the experiment in a controlled room temperature to maintain a better result.

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