1. Click Here To Start Experiment #1
Diffusion Rate
CHEMICAL DIFFUSION IN AGAR
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Diffusion is a process of equalization which involves movement of molecules from an area of high concentration to an area of low concentration
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This exercise investigates diffusion as it applies to movement of particles in a semi-solid material called agar
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Molecules are in a constant state of motion
The motion of these molecules are influenced by many factors
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5. FACTORS INFLUENCING DIFFUSION
1) Kinetic Energy 2) Nature of the environment 3) Size of the molecules
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KINETIC ENERGY
The driving force which causes the molecules to move
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7. Click Mouse Here to Perform the Exercise on Chemical Diffusion in Agar
NATURE OF THE ENVIRONMENT
The agar environment we will be using is a semisolid material through which we will measure the rate of diffusion of substances with different molecular size
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SIZE OF THE MOLECULES
Smaller molecules move faster than larger molecules
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9. Click Mouse Here to Perform the Exercise on Chemical Diffusion in Agar
LAB REPORT You will need to supply the following in your lab report for this experiment #1
1) Data Table for Diffusion of Different Molecular Weights
2) Answers to questions 1-4
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Click here to print a Data Table you will need for this experiment

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Procedure
Obtain two test tubes with agar *You can obtain the test tubes by clicking on the test tube rack on the shelf to the left
Test tube rack
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Procedure
2) Mark the test tubes as #1 and #2 *If you click on the pencil lying on the shelf to the left you can mark the tubes 1 2
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Procedure
3) Add a small amount of methylene blue to test tube #1 *You can click on the blue eyedropper lying on the shelf to the left to add the dye 1 2
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Procedure
4) Quickly click on the START button on the timer and record on your printed Data Sheet every 15 minutes the distance the dye has moved through the agar *You can measure the progress of the dye by observing the mm marks on the test tubes
Click here if you messed up and would like to try this experiment again 1 2
START
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Procedure
5) Add a small amount of potassium permanganate to test tube #2 *You can click on the green eyedropper lying on the shelf to the left to add the dye 1 2
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Procedure
6) Quickly click on the START button on the timer placed on the table and record every 15 minutes the distance the dye has moved through the agar *You can measure the progress of the dye by observing the mm marks on the test tubes
Click here if you messed up and would like to try this experiment again 1 2
START
00:00
50:00
45:00
60:00
40:00
55:00
25:00
10:00
05:00
35:00
15:00
20:00
30:00
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DATA
At this point you should have collected diffusion distance data for methylene blue and potassium permanganate
Include your data tables with your lab report when you are finished
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Data Table for Diffusion of Different Molecular Weights
Methylene blue (molecular weight of 320)
Time
15 min
30 min
45 min
60 min
Distance
Potassium permanganate (molecular weight of 158)
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Questions
Answer the questions (1-4) for this experiment
Hand your answers in with your lab report
What are the three things which influence the movement of molecules (and particles)?
In agar, what size of molecules move the fastest?
Which dye, the methylene blue or the potassium permanganate, diffused at the fastest rate?
Why did one dye diffuse faster than the other?
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18. At this point you have finished experiment #1 for this lab
Would you like to end your session or continue to the next experiment?
End this Session
Continue to Experiment #2 (PASSIVE MOVEMENT)
Continue to Experiment #3 (OSMOSIS AND DIALYSIS)

19. Data Table for Diffusion of Different Molecular Weights
Methylene blue (molecular weight of 320)
Time
15 min
30 min
45 min
60 min
Distance in mm
Potassium permanganate (molecular weight of 158)
You may also use this hyperlink to Print this Data Table if you are Online
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