Osmosis and Diffusion Lab Analysis and Conclusion
Analysis of Results
1. Determine percent change in mass for each item tested. (Final Mass-Initial Mass)/Initial Mass X 100 Calculate average percent change in mass for each test group.
2.Graph the results for your data. For this graph you will need to determine the independent and dependent variables to label the axis with and make a title for your graph. (Hint: one of your variables will be what you calculated in analysis question #1).
3. Why do you think you were asked to calculate the percent change in mass rather than simply using the change in mass?
4. Calculate Chi-Squared or Standard Deviation Analysis for your data.
If you changed, the type of potato...
5. Water potential values are useful because they allow us to predict the direction of the flow of water. Recall from the discussion that water flows from an area of higher water potential to an area of lower water potential. What direction did water flow in each type of potato? Why? Explain using isotonic, hypertonic, hypotonic and water potential terms.
6. Predict what would happen to the mass of each type of potato in this experiment if all the potatoes were placed in a different sucrose solution or distilled water. Explain your response.
7. Zucchini cores placed in sucrose solution at 27°C
resulted in the percent changes below after 24 hours. Make a graph of this data
with independent and dependent variables labeled and a title on the graph.
Determine the molar concentration of solutes within the zucchini cells (where
the line crosses zero).
% Change in Mass
Sucrose Molarity
20%
Distilled Water
10%
0.2 M
-3%
0.4 M
-17%
0.6 M
-25%
0.8 M
-30%
1.0 M
8. Calculate solute potential (ψs ) of the sucrose solution in which the mass of the zucchini cores does not change. Also calculate the water potential (ψ) of the solutes within the zucchini cores, knowing that the pressure potential of the solution is zero. ( remember ψ = ψp + ψs ) and ψs = -iCRT
If you changed the type of solution you put a potato or dialysis tube in...
5. Determine the molar concentration of the potato square of dialysis tube. This would be the sucrose molarity in which the mass of the potato squares/dialysis tube does not change. To find this, draw a straight line on the graph you made above through your data points (best fit line). The point at which this line crosses the x-axis represents the molar concentrations of sucrose with a water potential that is equal to the potato tissue/dialysis tube water potential. At this concentration there is no net gain or loss of water from the tissue/tube. Indicate this concentration of sucrose in the space provided below.
Molar concentration of sucrose in potato/tube= _______________________M
Calculate the solute potential of this sucrose solution using the following formula:
ψs = -iCRT
6. Calculate the water potential of the potato cells/dialysis tube, knowing that the pressure potential of the solution is zero. ( remember ψ = ψp + ψs )
7. Water potential values are useful because they allow us to predict the direction of the flow of water. Recall from the discussion that water flows from an area of higher water potential to an area of lower water potential. What direction did water flow in each of the solutions? Why? Explain using isotonic, hypertonic and hypotonic terms.
8. Explain what would happen to a red blood cell (RBC) placed in distilled water. Be sure to include which solution has the higher water potential in your explanation and why?
If you changed the solution you put in the dialysis tube...
5. Were the solutions you put into the dialysis tube isotonic, hypotonic or hypertonic to the solution in your cup? Explain individually if necessary.
6. Predict what would happen to the mass of each bag in this experiment if all the bags were placed in a 0.4 M sucrose solution instead of distilled water. Explain your response.
7. Zucchini cores placed in sucrose solution at 27°C
resulted in the percent changes below after 24 hours. Make a graph of this data
with independent and dependent variables labeled and a title on the graph.
Determine the molar concentration of solutes within the zucchini cells (where
the line crosses zero).
% Change in Mass
Sucrose Molarity
20%
Distilled Water
10%
0.2 M
-3%
0.4 M
-17%
0.6 M
-25%
0.8 M
-30%
1.0 M
8. Calculate solute potential (ψs ) of the sucrose solution in which the mass of the zucchini cores does not change. Also calculate the water potential (ψ) of the solutes within the zucchini cores, knowing that the pressure potential of the solution is zero. ( remember ψ = ψp + ψs ) and ψs = -iCRT
.
If you changed the mass of the original potato...
5. Explain the percent change in mass for each of your test groups why were they different or the same. Why did water move? Be sure to discuss hypotonic, hypertonic and isotonic solutions as well as water potential.
6. Zucchini cores placed in sucrose solution at 27°C
resulted in the percent changes below after 24 hours. Make a graph of this data
with independent and dependent variables labeled and a title on the graph.
Determine the molar concentration of solutes within the zucchini cells (where
the line crosses zero).
% Change in Mass
Sucrose Molarity
20%
Distilled Water
10%
0.2 M
-3%
0.4 M
-17%
0.6 M
-25%
0.8 M
-30%
1.0 M
7. Calculate solute potential (ψs ) of the sucrose solution in which the mass of the zucchini cores does not change. Also calculate the water potential (ψ) of the solutes within the zucchini cores, knowing that the pressure potential of the solution is zero. ( remember ψ = ψp + ψs ) and ψs = -iCRT
8. Explain what would happen to a red blood cell (RBC) placed in distilled water. Be sure to include which solution has the higher water potential in your explanation and why?
Conclusion
As usual using your blue guide.