Question

Experiment 1: Diffusion through Gelatin

Data Tables

Purpose (What question is this experiment designed to answer?):

Hypothesis (Based on what you’ve learned in the pre-lab materials, write and If/Then statement regarding the outcome of this experiment.):

Table 1: Diffusion Data

Test Tube	Distance After 4 Hours (mm)	Distance After 24 Hours (mm)
A
B
C

Claim (What are the results of your experiment?):

Evidence (What data did you collect that supports your claim? Explain the meaning behind the data and the calculations.):

Post-Lab Questions

1. Create a graph of your results with time (seconds) on the x-axis and distance of diffusion (mm) on the y-axis. There should be one line for each solution on your graph.
2. Which solution diffused the fastest?
3. Does the rate of diffusion correspond with the molecular weight of the solution? Explain your answer.
4. Why you think there was or was not a correlation between molecular weight and rate of diffusion?
5. What does the rate of diffusion tell you about limitations of cell size?

Reflection (Discuss what you have learned by doing this experiment. How have your ideas changed? Do you have any new questions? What connections did you make between the lab and lecture?):

EXPERIMENT 1: DIFFUSION THROUGH GELATIN In this experiment, you will observe the effect of molecular weight on the ability of solutes to diffuse into gelatin. PROCEDURE 1. Record the Purpose and your Hypothesis for this experiment in your assessment package. 2. Label the three test tubes A-C and place them in the test tube rack. L3. Pour the contents of the Knox gelatin packet into a 250 ml beaker. 4. Fill the beaker to the 100 mL line with hot water, and stir until the gelatin powder has dissolved. Note: The water does not need to be boiling. Hot tap water will be sufficient to prepare the gelatin. 5. Divide the solution among the three test tubes, filling each approximately % of the way to the top. 6. Allow the test tubes to sit overnight to solidify. If possible, place the test tube rack in a refrigerator. 7. Once the gelatin has solidified, mark where the top of the gel sits in each test tube with a permanent marker. 8. Pipette 4 mL of 0.05% methylene blue solution into Test Tube A. Key Technique 9. Pipette 4 mL of lodine-Potassium lodide (IKI) into Test Tube B. 10. Pipette 2 mL of 0.05% methylene blue and 2 mL of Klinto Test Tube C. 11. Place a stopper on each of the test tubes, and allow them to sit at room temperature. 12. After 4 hours, measure the distance the solution has traveled through the gel in millimeters. Record the distance in Table 1 13. Repeat these measurements after 24 hours and record in Table 1.

Answer 1

It would have been better if you have mentioned observed results in the table after your experiment. Here I can give you probable result.

Molecular Weight of Methylene Blue = 319.85 g/mol

Molecular Weight of Iodine Pottasium Iodide (IKI) = 292.9073 g/mol

Purpose: The effect of molecular weight on the ability of solutes to diffuse through gelatin

Hypothesis: Diffusion is the process of moving molecules from areas of high concentration to areas of low concentration. Higher molecular weight diffuse slowly than lighter molecular weight solutes. So there should be there is a linear relationship between the diffusion distance squared and diffusion time.

Results:

Test Tube	Distance After 4 Hours (mm)	Distance After 24 Hours (mm)
A	2mm	5mm
B	4mm	12mm
C	1mm (inner Methylene Blue) 3mm (outer IKI)	4mm (inner Methylene Blue) 11mm (outer IKI)

Claim: Yes, there is a linear realtionship between diffusion distance and diffusion time. Molecular weight affect the rate of diffusion.

Evidence: Increased diffusion distance in all three tube with increasing time support the claim made in the experiment.

Here you can see linear relationship (if you connect blue dots).

Time in hours (y axis) vs Diffusion Distance in mm (x axis) Tube A Tube B Tube C 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14

Note: initial diffusion would be slow

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